A good online resource for the chapter on Alkynes
http://www.chem.ucalgary.ca/courses/351/Carey5th/Ch09/ch9-1.html
Today morning I studied the chapter on Alkynes from TMH study guide. Preparation of alkynes and reactions of alkynes are the two topics in this chapter. Both these topics are covered in detail in the above online resource.
Wednesday, August 29, 2007
Monday, August 27, 2007
Recall Concepts F to J
F
Factor label method, Fermentation, Fitration, Fission, Fluorohydrocarbons, "f" orbital, formula mass, Fractinal distillation, Freezing point, fuel value, Fusion
G
Galvanic cell, Gama radiation, Ga constant, Gas density, Gas laws, Gay-Lussac's law, Gel, Geometrical isomer, Graphing, Group, Group IA metals, Group IIA metals, Group IIIA elements, Group IVA elements, Group VA, VIA, VIIA, VIIIA elements,
H
Haber process, Half life, Half reaction method, Halogens, Homologous series, Humidity, Hund's rule, Hydrates, Hydration, Hydride ion, Hydrocarbons,Hydrogen bond, Hydrolysis, Hydrometer, Hydrophobic, Hydroxy salt, Hygroscopic, Hypertonic, Hypothesis, Hypotonic
Factor label method, Fermentation, Fitration, Fission, Fluorohydrocarbons, "f" orbital, formula mass, Fractinal distillation, Freezing point, fuel value, Fusion
G
Galvanic cell, Gama radiation, Ga constant, Gas density, Gas laws, Gay-Lussac's law, Gel, Geometrical isomer, Graphing, Group, Group IA metals, Group IIA metals, Group IIIA elements, Group IVA elements, Group VA, VIA, VIIA, VIIIA elements,
H
Haber process, Half life, Half reaction method, Halogens, Homologous series, Humidity, Hund's rule, Hydrates, Hydration, Hydride ion, Hydrocarbons,Hydrogen bond, Hydrolysis, Hydrometer, Hydrophobic, Hydroxy salt, Hygroscopic, Hypertonic, Hypothesis, Hypotonic
Quotations - Read and Think about them
Be Passionately Persistent
Success doesn't just happen. It is made by those who are so passionately persistent that they will not accept failure as long as opportunity to try again is available. Passion is a learned attitude and persistence is a learned behaviour. Together they will serve you well in life. in your career, and in this endeavour.
Have Goals in Your Line of Vision
Obstacles are what you see when take your eyes off the goal, and not having a goal is the biggest obsctacle of all.
Success doesn't just happen. It is made by those who are so passionately persistent that they will not accept failure as long as opportunity to try again is available. Passion is a learned attitude and persistence is a learned behaviour. Together they will serve you well in life. in your career, and in this endeavour.
Have Goals in Your Line of Vision
Obstacles are what you see when take your eyes off the goal, and not having a goal is the biggest obsctacle of all.
Sunday, August 19, 2007
Online resource - one more for Organic Chemistry
http://library.tedankara.k12.tr/carey/
Contents of the site
Project Overview
How to use this resource
General Information
Feedback ?
Chapter 1: Chemical Bonding
Chapter 2: Alkanes
Chapter 3: Conformational Analysisof Alkanes and Cycloalkanes
Chapter 4: Alcohols and Alkyl Halides
Chapter 5: Structure and Preparationof Alkenes. Elimination Reactions
Chapter 6: Reactions of Alkenes.Addition Reactions
Chapter 7: Stereochemistry
Chapter 8: Nucleophilic Substitution
Chapter 9: Alkynes
Chapter 10: Conjugation in Alkadienesand Allylic Systems
Chapter 11: Arenes and Aromaticity
Chapter 12: Reactions of Arenes:Electrophilic Aromatic Substitution
Chapter 13: Spectroscopy
Chapter 14:
Chapter 15:
Chapter 16:
Chapter 17: Aldehydes and Ketones.Nucleophilic Addition to C=O
Chapter 18: Enols and Enolates
Chapter 19: Carboxylic Acids
Chapter 20: Carboxylic Acid Derivatives.Nucleophilic Acyl Substitution
Chapter 21: Ester Enolates
Contents of the site
Project Overview
How to use this resource
General Information
Feedback ?
Chapter 1: Chemical Bonding
Chapter 2: Alkanes
Chapter 3: Conformational Analysisof Alkanes and Cycloalkanes
Chapter 4: Alcohols and Alkyl Halides
Chapter 5: Structure and Preparationof Alkenes. Elimination Reactions
Chapter 6: Reactions of Alkenes.Addition Reactions
Chapter 7: Stereochemistry
Chapter 8: Nucleophilic Substitution
Chapter 9: Alkynes
Chapter 10: Conjugation in Alkadienesand Allylic Systems
Chapter 11: Arenes and Aromaticity
Chapter 12: Reactions of Arenes:Electrophilic Aromatic Substitution
Chapter 13: Spectroscopy
Chapter 14:
Chapter 15:
Chapter 16:
Chapter 17: Aldehydes and Ketones.Nucleophilic Addition to C=O
Chapter 18: Enols and Enolates
Chapter 19: Carboxylic Acids
Chapter 20: Carboxylic Acid Derivatives.Nucleophilic Acyl Substitution
Chapter 21: Ester Enolates
Saturday, August 18, 2007
Study Notes - Organic Chemistry - Roberts - Stewarts - Caserio - Ch 2
Ch 2: the C1 and C2 hydrocarbons
Things I came to know or understood better.
Conformations
Structure designates the order in which the atoms are joined to each other. But a structure does not necessarily specify the exact shape of a molecule because rotation of atoms about single bonds of Carbon could lead, even for a molecule as simple as ethane, to an infinite number of different arrangements of atoms in space. There are called conformations and depend on the angular relationship between hydrogens on each carbon. Two extreme arrangements - eclipsed position: hydrogens on the forward carbon directly in front of those on the back carbon. - staggered conformation has each of the hydrogens n the forward carbon between each of the hydrogens on the back carbon.
sawhorse diagram
Newman diagram
Reaction intermediates
Methyl radical
Methyl Cation - carbonium ion
Methyl Anion - Carbanion
Methylene (a carbene)
Things I came to know or understood better.
Conformations
Structure designates the order in which the atoms are joined to each other. But a structure does not necessarily specify the exact shape of a molecule because rotation of atoms about single bonds of Carbon could lead, even for a molecule as simple as ethane, to an infinite number of different arrangements of atoms in space. There are called conformations and depend on the angular relationship between hydrogens on each carbon. Two extreme arrangements - eclipsed position: hydrogens on the forward carbon directly in front of those on the back carbon. - staggered conformation has each of the hydrogens n the forward carbon between each of the hydrogens on the back carbon.
sawhorse diagram
Newman diagram
Reaction intermediates
Methyl radical
Methyl Cation - carbonium ion
Methyl Anion - Carbanion
Methylene (a carbene)
Study Notes - Organic Chemistry - Roberts - Stewarts - Caserio
I have got a book from our library on Organic Chemistry by Roberts, Stewart, and Caserio. Earlier as I wanted to read it, it was difficult to follow the first chapter. But now that I read most of the lessons of JEE syllabus from the end, I am feeling comfortable to read this book. Now.
The First Chapter - Introduction
Some new things (either in explanation or in content) that I came to know
Electronegativity series
Hydrogen Carbon Nitrogen Oxygen Flourine
2.0 2.5 3.0 3.5 4.0
due to the big difference in electronegativity between carbon and flourine, the covalent bond between them is polar covalent bond.
The polar covalent bond between C and O will have less polarity than that between C and F.
Hydrogen bond is a bond between molecules giving rise to intermolecular force. To be effective, hydrogen bonding requires the presence of -OH, -N-H, or F-H group; in other words, a hydrogen atom joined to a small electronegative atom.
The covalent bonds to such hydrogen atoms are strongly polarised toward the electronegative atom, for example molecule R-O-H. In such a molecule, the partially positive hydrogen will be attracted toward the partially negative oxygen atom in a neighboring molecule. Such bonds are continually formed and broken. the most important group responsible for hydrogen bonding is the hydroxyl group -OH.
The First Chapter - Introduction
Some new things (either in explanation or in content) that I came to know
Electronegativity series
Hydrogen Carbon Nitrogen Oxygen Flourine
2.0 2.5 3.0 3.5 4.0
due to the big difference in electronegativity between carbon and flourine, the covalent bond between them is polar covalent bond.
The polar covalent bond between C and O will have less polarity than that between C and F.
Hydrogen bond is a bond between molecules giving rise to intermolecular force. To be effective, hydrogen bonding requires the presence of -OH, -N-H, or F-H group; in other words, a hydrogen atom joined to a small electronegative atom.
The covalent bonds to such hydrogen atoms are strongly polarised toward the electronegative atom, for example molecule R-O-H. In such a molecule, the partially positive hydrogen will be attracted toward the partially negative oxygen atom in a neighboring molecule. Such bonds are continually formed and broken. the most important group responsible for hydrogen bonding is the hydroxyl group -OH.
Friday, August 17, 2007
Chemistry Online Resources - Elmhurst.edu
Another good resource
http://www.elmhurst.edu/~chm/vchembook/index.html
The site has provision for some online quiz questions also at the end
http://www.elmhurst.edu/~chm/vchembook/index.html
The site has provision for some online quiz questions also at the end
Wednesday, August 15, 2007
TMH-JEE-Chemistry- book-chapters Ch.21 Alkanes Study Guide/Note
JEE Syllabus
Preparation, properties and reactions of alkanes:
Homologous series,
physical properties of alkanes (melting points, boiling points and density); Combustion and halogenation of alkanes;
Preparation of alkanes by Wurtz reaction and decarboxylation reactions.
--------------------
Main Topics Covered in the TMH Book
METHODS OF PREPARATION
PHYSICAL PROPERTIES
CHEMICAL PROPERTIES
-----------------------
Alkanes: Introduction
Alkanes are saturated hydrocarbons containing only carbon-carbon single bonds in their molecules.
Thye are also called paraffins (meaning little affinity or reactivity, we will see later why it is so).
Alkanes are divided into 1. Open chain or acyclic Alkanes and 2. CycloAlkanes or cyclic alkanes.
Nomenclature of alkanes
Examples:
2,2-Dimethylpropane
2-Methylpentane
3-Methylhexane
3-ehtyl-2-methylhexane
4-ehtyl-2,4-dimethylhexane
4-(1-methyl ethyl) heptane or 4-Isopropylheptane
Straight chain alkanes or normal alkanes (n-alkanes): All the carbon atoms are attached by covalent bonds in a continuous chain.
Branched alkanes:
Iso-alkanes: In these, one carbon chain is attached to the second carbon atom of the long chain (parent chain).
Neo-alkanes: In these two single carbon branches are attached to the second carbon atom of the long chain.
Conformations in alkanes
The C-C bond in alkanes is a sigma bond and has cylindrical symmetry. Due to this, atoms involved can rotate about the axis of the bond without affecting the overlap of orbitals that form the bond. So rotation about C-C bond is quite free. Therefore hydrogen atoms can have different spatial arrangement while maintaing the bond and the bond angle between H-C-H. Such different spatial arrangments are called conformations, conformational isomers (conformers) or rotational isomers (rotamers).
the different arrangements of atoms in a molecule which can be obtained due to rotation about carbon-carbon single bond are called conformations.
To represent conformations Saw horse diagrams and Newman projection diagrams are used.
Conformations of ethane, propane, butanecyclopropane, cyclopentane, cyclohexane are discussed in Jauhar's book.
Preparation of alkanes
General methods
1. From unsaturated hydrocarbons (alkenes and alkynes)
2. From alkyl halides
3. From carboxylic acids and their salts
1. From unsaturated hydrocarbons (alkenes and alkynes)
By catalytic hydrogenation alkenes and alkynes are converted into alkanes (Note that this point will come in alkenes and alkynes chapter as reactions of them).
Ni, Pt or Pd in the form of fine powder are used as catalysts. A temperature of 523-573 K needs to be employed.
Methane cannot be prepared by this method because alkenes or alkynes will have two carbons at their lowest level.
2. From alkyl halides
a) Wurtz reaction (specially in syllabus)
When an alkyl halide (usually bromide or iodide) is treated with sodium in dry ether, a symmetrical alkane containing both twice the number of carbon atoms of alkyl halide is obtained. The equation of the reaction will make the statement more clear.
RX + 2Na + XR ---> R-R + 2NaX catalyst sodium in dry ether
In the reaction different alkyl halides can also be used in stead of a single halide. If two different halides are taken with the aim of preparing an alkane with odd number of carbon atoms, a mixture of products is obtained in stead of a single alkane. This is because in this case three reactions takes place and three different products are obtained.
b) Reduction of alkyl halides
Reducing agents can be used to add hydrogen to the halide and remove the halogen atom.
i) Zinc + HCl is one reducing agent.
ii) Catalytic hydrogenation using Pd or Pt as catalyst
iii) Hydrogen iodide (halogen acid) in the presence of red phosphorous also acts as reducing agent. In this reaction phosphorous combines with iodine to form phosphorous triiodide.
iv) zinc copper couple and alcohol
c) By the use of Grignard reagent
Alkyl halides react with magnesium metal in diethyl ether to form alkyl magnesium halides which are called as Grignard reagents. (This reaction will come in alkyl halides chapter also)
Grignard reagetns are highly reactive and are easily decomposed by water or alcohol to form alkanes
RMgX + HOH (H2O) ---> RH + Mg(OH)X
3. From carboxylic acids and their salts
a) Decarboxylation reaction
b) Kolbe's reaction
c) Reduction of carboxylic acid
a) Decarboxylation reaction
When sodium salt of a monocarboxylic acid is heated with soda lime (amixture of NaOH and Cao in the ratio of 3:1) at about 630 K, alkane is formed.
RCOONa + NaOH -->RH + Na2CO3
In this reaction a CO2 group is removed from carboxylic acid and therefore the reaction is called decarboxylation.
(Note this reaction will be discussed in carboxylic acids chapter)
b) Kolbe's reaction
When an acqueous solution of sodium or potassium salt of carboxylic acid is eletrolysed alkane is evolved at the anode.
Kolbe's reaction can also be used like wurtz reaction for preparing alkanes with even number of carbon atoms.
c) Reduction of carboxylic acid
Carboxylic acids are reduced to alkanes by hydroiodic acid (HI). In this reaction COOH group in the carboxylic acid is reduced to CH3 group.
The methods in this section can be summarised as
R-COONa ---> RH
R-COONa ---> R-R
R-COOH---> R-CH3
Industrial method: Petroleum provides the natural source of alkanes.
Physical properties of alkanes
1. State
2. Boiling point
3. Melting point
4. Solubility
5. Density
Chemical properties or reactions
1. Substitution reactions of alkanes
2. Oxidation
3. Action of steam
4. Isomerisation
5. Aromatization
6. Thermal decomposition or fragmentation
Alkanes – Simple Questions
1. What happens to boiling point of alkanes as molecular mass increases?
2. What happens to boiling point of branched isomers of alkanes?
3. Under what conditions does monochlorination of methane takes place?
4. What is the `reaction in Kolbe Electrolytic method of preparing alkanes?
5. What are the reactants and products in hydrolysis of Grignard reagent?
6. In the case of halogenation of alkanes, what is order of reactivity among chlorine, fluorine, and bromine?
7. At ordinary temperatures, why is ultraviolet radiation required to initiate a reaction between halogens and alkanes?
8. What do you understand by 1 degree H, 2 degree H and 3 degree H?
9. What is the difference in reactions between an alkane and fluorine and an alkane and bromine?
10. What is the major product in reaction between bromine and n-butane?
11. What are the products of reaction between n-butane and chlorine at room temperature and sunlight?
12. How do you get iso-butane from n-butane?
13. When do you get aromatic compounds from alkanes?
14. What is the more common name of Methane?
15. What is % composition of Methane in coal gas?
16. How do you produce methane from aluminium chloride?
17. What are the reactants and products of Wurtz reaction?
Answer these questions. This will help you to answer other complex ways of asking questions like MCQs, multiple matching, passage based questions and fact & cause questions.
-------------
web sites
The homologous aliphatic series of ALKANES
http://www.docbrown.info/page06/DFalkanes.htm
Preparation, properties and reactions of alkanes:
Homologous series,
physical properties of alkanes (melting points, boiling points and density); Combustion and halogenation of alkanes;
Preparation of alkanes by Wurtz reaction and decarboxylation reactions.
--------------------
Main Topics Covered in the TMH Book
METHODS OF PREPARATION
PHYSICAL PROPERTIES
CHEMICAL PROPERTIES
-----------------------
Alkanes: Introduction
Alkanes are saturated hydrocarbons containing only carbon-carbon single bonds in their molecules.
Thye are also called paraffins (meaning little affinity or reactivity, we will see later why it is so).
Alkanes are divided into 1. Open chain or acyclic Alkanes and 2. CycloAlkanes or cyclic alkanes.
Nomenclature of alkanes
Examples:
2,2-Dimethylpropane
2-Methylpentane
3-Methylhexane
3-ehtyl-2-methylhexane
4-ehtyl-2,4-dimethylhexane
4-(1-methyl ethyl) heptane or 4-Isopropylheptane
Straight chain alkanes or normal alkanes (n-alkanes): All the carbon atoms are attached by covalent bonds in a continuous chain.
Branched alkanes:
Iso-alkanes: In these, one carbon chain is attached to the second carbon atom of the long chain (parent chain).
Neo-alkanes: In these two single carbon branches are attached to the second carbon atom of the long chain.
Conformations in alkanes
The C-C bond in alkanes is a sigma bond and has cylindrical symmetry. Due to this, atoms involved can rotate about the axis of the bond without affecting the overlap of orbitals that form the bond. So rotation about C-C bond is quite free. Therefore hydrogen atoms can have different spatial arrangement while maintaing the bond and the bond angle between H-C-H. Such different spatial arrangments are called conformations, conformational isomers (conformers) or rotational isomers (rotamers).
the different arrangements of atoms in a molecule which can be obtained due to rotation about carbon-carbon single bond are called conformations.
To represent conformations Saw horse diagrams and Newman projection diagrams are used.
Conformations of ethane, propane, butanecyclopropane, cyclopentane, cyclohexane are discussed in Jauhar's book.
Preparation of alkanes
General methods
1. From unsaturated hydrocarbons (alkenes and alkynes)
2. From alkyl halides
3. From carboxylic acids and their salts
1. From unsaturated hydrocarbons (alkenes and alkynes)
By catalytic hydrogenation alkenes and alkynes are converted into alkanes (Note that this point will come in alkenes and alkynes chapter as reactions of them).
Ni, Pt or Pd in the form of fine powder are used as catalysts. A temperature of 523-573 K needs to be employed.
Methane cannot be prepared by this method because alkenes or alkynes will have two carbons at their lowest level.
2. From alkyl halides
a) Wurtz reaction (specially in syllabus)
When an alkyl halide (usually bromide or iodide) is treated with sodium in dry ether, a symmetrical alkane containing both twice the number of carbon atoms of alkyl halide is obtained. The equation of the reaction will make the statement more clear.
RX + 2Na + XR ---> R-R + 2NaX catalyst sodium in dry ether
In the reaction different alkyl halides can also be used in stead of a single halide. If two different halides are taken with the aim of preparing an alkane with odd number of carbon atoms, a mixture of products is obtained in stead of a single alkane. This is because in this case three reactions takes place and three different products are obtained.
b) Reduction of alkyl halides
Reducing agents can be used to add hydrogen to the halide and remove the halogen atom.
i) Zinc + HCl is one reducing agent.
ii) Catalytic hydrogenation using Pd or Pt as catalyst
iii) Hydrogen iodide (halogen acid) in the presence of red phosphorous also acts as reducing agent. In this reaction phosphorous combines with iodine to form phosphorous triiodide.
iv) zinc copper couple and alcohol
c) By the use of Grignard reagent
Alkyl halides react with magnesium metal in diethyl ether to form alkyl magnesium halides which are called as Grignard reagents. (This reaction will come in alkyl halides chapter also)
Grignard reagetns are highly reactive and are easily decomposed by water or alcohol to form alkanes
RMgX + HOH (H2O) ---> RH + Mg(OH)X
3. From carboxylic acids and their salts
a) Decarboxylation reaction
b) Kolbe's reaction
c) Reduction of carboxylic acid
a) Decarboxylation reaction
When sodium salt of a monocarboxylic acid is heated with soda lime (amixture of NaOH and Cao in the ratio of 3:1) at about 630 K, alkane is formed.
RCOONa + NaOH -->RH + Na2CO3
In this reaction a CO2 group is removed from carboxylic acid and therefore the reaction is called decarboxylation.
(Note this reaction will be discussed in carboxylic acids chapter)
b) Kolbe's reaction
When an acqueous solution of sodium or potassium salt of carboxylic acid is eletrolysed alkane is evolved at the anode.
Kolbe's reaction can also be used like wurtz reaction for preparing alkanes with even number of carbon atoms.
c) Reduction of carboxylic acid
Carboxylic acids are reduced to alkanes by hydroiodic acid (HI). In this reaction COOH group in the carboxylic acid is reduced to CH3 group.
The methods in this section can be summarised as
R-COONa ---> RH
R-COONa ---> R-R
R-COOH---> R-CH3
Industrial method: Petroleum provides the natural source of alkanes.
Physical properties of alkanes
1. State
2. Boiling point
3. Melting point
4. Solubility
5. Density
Chemical properties or reactions
1. Substitution reactions of alkanes
2. Oxidation
3. Action of steam
4. Isomerisation
5. Aromatization
6. Thermal decomposition or fragmentation
Alkanes – Simple Questions
1. What happens to boiling point of alkanes as molecular mass increases?
2. What happens to boiling point of branched isomers of alkanes?
3. Under what conditions does monochlorination of methane takes place?
4. What is the `reaction in Kolbe Electrolytic method of preparing alkanes?
5. What are the reactants and products in hydrolysis of Grignard reagent?
6. In the case of halogenation of alkanes, what is order of reactivity among chlorine, fluorine, and bromine?
7. At ordinary temperatures, why is ultraviolet radiation required to initiate a reaction between halogens and alkanes?
8. What do you understand by 1 degree H, 2 degree H and 3 degree H?
9. What is the difference in reactions between an alkane and fluorine and an alkane and bromine?
10. What is the major product in reaction between bromine and n-butane?
11. What are the products of reaction between n-butane and chlorine at room temperature and sunlight?
12. How do you get iso-butane from n-butane?
13. When do you get aromatic compounds from alkanes?
14. What is the more common name of Methane?
15. What is % composition of Methane in coal gas?
16. How do you produce methane from aluminium chloride?
17. What are the reactants and products of Wurtz reaction?
Answer these questions. This will help you to answer other complex ways of asking questions like MCQs, multiple matching, passage based questions and fact & cause questions.
-------------
web sites
The homologous aliphatic series of ALKANES
http://www.docbrown.info/page06/DFalkanes.htm
Saturday, August 11, 2007
TMH-JEE-Chemistry- book-chapters Ch.30 Amines Study Guide/Note
JEE syllabus:
JEE Syllabus
Amines:
Preparation, Properties, Reactions
Charcteristic reactions
Basicity of substituted anilines and aliphatic amines,
Preparation from nitro compounds,
Reaction with nitrous acid,
Azo coupling reaction of diazonium salts of aromatic amines,
Sandmeyer and related reactions of diazonium salts;
Carbylamine reaction;
------------------
Main Topics Covered in the TMH Book
METHODS OF PREPARATION
PHYSICAL PROPERTIES
CHEMICAL REACTIONS
SYNTHETIC USE OF DIAZONIUM SALT
SEPARATION OF A MIXTURE OF AMINES
---------------------------
Amines are regarded as derivatives of ammonia in which one, two or all three hydrogen atoms are replaced by alkyl or aryl group.
NH3 - H = RNH2; (Primary amine) characteritic group NH2 amino
RNH2 - H = R2NH;(secondary amine) characteritic group NH imino
R2NH - H = R3N (tertiary amine) characteritic group N tert-nitrogen
The amines are classified as primary, secondary and tertiary according to one, two or three hydrogen atoms of ammonia are replaced by alkyl or aryl groups.
In addition, there is another class known as quaternary ammonium compounds. These compounds are regarded as derivatives of ammonium salts in which all the four hydrogen atoms are replaced by alkyl or aryl groups.
Nomenclature of amines
IUPAC NAMES
Aliphatic amines
Methanamine
Ethanamine
1-Propanamine
2-Propanamines
N-methylmethanamine
N-Methylethanamine
N,N-Dimethylmethanamine
Aromatic amines
Benzenamine - can also be written as amino benzene
2-Methylbenzenamine
3-Methylbenzenamine
4-Methylbenzenamine
N-Methylbenzenamine
N,N-Dieethylbenzenamine
Isomerism in amines
1. Chain isomerism
2. Metamerism
3. Position isomerism
4. functional isomerism
Preparation of amines
1. From alkyl halides
2. From Nitro compounds (specially mentioned in JEE syllabus)
3.From nitriles (cyanides) and isonitriles (isocyanides)
4. From amides
5. From oximes
6. from aldehydes and ketones
Industrial preparation
1. from alcohols
2.from aniline
Physical properties
1. State and smell
2. B.P.
Chemical Properties
1. Reaction with water (Basic character of amines) (specially mentioned in JEE syllabus)
2. Reaction with acids
3. Reaction with metal ions
4. Alkylation
5. Acylation (reaction with acid chlorides and acid anhydrides)
6. Benzoylation
7. schiff's base formation
8. Oxidation
9. Carbalamine reaction (specially mentioned in JEE syllabus)
10. Reaction with nitrous acid (specially mentioned in JEE syllabus)
11. Reaction with Grignard reagent
12. Carbon disulphide
13. Carbonyl chloride
14. Ring substitution in aromatic amines
15. coupling of diazonium salts (specially mentioned in JEE syllabus)
Sandmeyer and related reactions (specially mentioned in JEE syllabus)
The diazonium salts have the general formula ArN2+X-, where X- may be an anion like Cl-, Br- etc.
The group N2+ (-N≡N+) is called diazonium ion group.
Sandmeyer reaction is a substitution reaction.
In the substistution reactions, nitrogen of the salts is lost as N2 and different groups are introduced in its place.
Various substitution reactions of diazonium salts
1. Replacement by -OH group. By boiling or by steam boiling. Phenol is formed
2. Replacement by hydrogen. By treatment with hypophophorous acid. Benzene is obtained.
3. Replacement by Cl and Br group.When the salt is warmed with cuprous chloride or cuprous bromide the corresponding halide is formed. This reaction is called Sandmeyer reaction
-------------
Past JEE Questions
How will you convert 4-nitroaniline to 1,2,3-tribromobenzene? 1990
1991
Identify A, B and c in the following reactions
C6H5COOH + PCl5--->A
A + NH3---> B
B+ P2O5---->C6H5CN
C6H5CN +(H2, Ni)--->C
Some of the reactants can be catalysts.
1994
How will you synthesize benzamide from nitrobenzene.
1997
How will you prepare m-bromoiodo benzene from benzene?
1998
Write the structures of two products of the reaction.
CH3CONHC6H5 (Br2,Fe) ---->
1998
Arrange the following in the decreasing order of basic character
Methylamine, dimethylamine, aniline, N-methylaniline
2000
How would you bring about conversion of Aniline to Benzylamine.
2001
Aspartame an artificial sweetener, is a peptide and has the following structure.
(Structure not given here by me)
i) Identify the four functional groups.
ii) Write the zwitter ionic structure
iii) Write the structures of the amino acids obtained from the hydrolysis of aspartame.
iv) Which of the two amino acids is more hydrophobic?
-----------------
web sites
Notes on the Classification, Structure and Nomenclature-naming of Organic compounds containing Nitrogen
http://www.docbrown.info/page07/orgNcmpds.htm
JEE Syllabus
Amines:
Preparation, Properties, Reactions
Charcteristic reactions
Basicity of substituted anilines and aliphatic amines,
Preparation from nitro compounds,
Reaction with nitrous acid,
Azo coupling reaction of diazonium salts of aromatic amines,
Sandmeyer and related reactions of diazonium salts;
Carbylamine reaction;
------------------
Main Topics Covered in the TMH Book
METHODS OF PREPARATION
PHYSICAL PROPERTIES
CHEMICAL REACTIONS
SYNTHETIC USE OF DIAZONIUM SALT
SEPARATION OF A MIXTURE OF AMINES
---------------------------
Amines are regarded as derivatives of ammonia in which one, two or all three hydrogen atoms are replaced by alkyl or aryl group.
NH3 - H = RNH2; (Primary amine) characteritic group NH2 amino
RNH2 - H = R2NH;(secondary amine) characteritic group NH imino
R2NH - H = R3N (tertiary amine) characteritic group N tert-nitrogen
The amines are classified as primary, secondary and tertiary according to one, two or three hydrogen atoms of ammonia are replaced by alkyl or aryl groups.
In addition, there is another class known as quaternary ammonium compounds. These compounds are regarded as derivatives of ammonium salts in which all the four hydrogen atoms are replaced by alkyl or aryl groups.
Nomenclature of amines
IUPAC NAMES
Aliphatic amines
Methanamine
Ethanamine
1-Propanamine
2-Propanamines
N-methylmethanamine
N-Methylethanamine
N,N-Dimethylmethanamine
Aromatic amines
Benzenamine - can also be written as amino benzene
2-Methylbenzenamine
3-Methylbenzenamine
4-Methylbenzenamine
N-Methylbenzenamine
N,N-Dieethylbenzenamine
Isomerism in amines
1. Chain isomerism
2. Metamerism
3. Position isomerism
4. functional isomerism
Preparation of amines
1. From alkyl halides
2. From Nitro compounds (specially mentioned in JEE syllabus)
3.From nitriles (cyanides) and isonitriles (isocyanides)
4. From amides
5. From oximes
6. from aldehydes and ketones
Industrial preparation
1. from alcohols
2.from aniline
Physical properties
1. State and smell
2. B.P.
Chemical Properties
1. Reaction with water (Basic character of amines) (specially mentioned in JEE syllabus)
2. Reaction with acids
3. Reaction with metal ions
4. Alkylation
5. Acylation (reaction with acid chlorides and acid anhydrides)
6. Benzoylation
7. schiff's base formation
8. Oxidation
9. Carbalamine reaction (specially mentioned in JEE syllabus)
10. Reaction with nitrous acid (specially mentioned in JEE syllabus)
11. Reaction with Grignard reagent
12. Carbon disulphide
13. Carbonyl chloride
14. Ring substitution in aromatic amines
15. coupling of diazonium salts (specially mentioned in JEE syllabus)
Sandmeyer and related reactions (specially mentioned in JEE syllabus)
The diazonium salts have the general formula ArN2+X-, where X- may be an anion like Cl-, Br- etc.
The group N2+ (-N≡N+) is called diazonium ion group.
Sandmeyer reaction is a substitution reaction.
In the substistution reactions, nitrogen of the salts is lost as N2 and different groups are introduced in its place.
Various substitution reactions of diazonium salts
1. Replacement by -OH group. By boiling or by steam boiling. Phenol is formed
2. Replacement by hydrogen. By treatment with hypophophorous acid. Benzene is obtained.
3. Replacement by Cl and Br group.When the salt is warmed with cuprous chloride or cuprous bromide the corresponding halide is formed. This reaction is called Sandmeyer reaction
-------------
Past JEE Questions
How will you convert 4-nitroaniline to 1,2,3-tribromobenzene? 1990
1991
Identify A, B and c in the following reactions
C6H5COOH + PCl5--->A
A + NH3---> B
B+ P2O5---->C6H5CN
C6H5CN +(H2, Ni)--->C
Some of the reactants can be catalysts.
1994
How will you synthesize benzamide from nitrobenzene.
1997
How will you prepare m-bromoiodo benzene from benzene?
1998
Write the structures of two products of the reaction.
CH3CONHC6H5 (Br2,Fe) ---->
1998
Arrange the following in the decreasing order of basic character
Methylamine, dimethylamine, aniline, N-methylaniline
2000
How would you bring about conversion of Aniline to Benzylamine.
2001
Aspartame an artificial sweetener, is a peptide and has the following structure.
(Structure not given here by me)
i) Identify the four functional groups.
ii) Write the zwitter ionic structure
iii) Write the structures of the amino acids obtained from the hydrolysis of aspartame.
iv) Which of the two amino acids is more hydrophobic?
-----------------
web sites
Notes on the Classification, Structure and Nomenclature-naming of Organic compounds containing Nitrogen
http://www.docbrown.info/page07/orgNcmpds.htm
TMH-JEE-Chemistry- book-chapters Ch.31 Carbohydrates Study Guide/Note
JEE Syllabus
Carbohydrates:
Classification;
mono and di-saccharides (glucose and sucrose);
Oxidation, reduction,
glycoside formation and hydrolysis of sucrose.
--------------
Main Topics Covered in the TMH Book
MONOSACCHARIDES
DISACCHARIDES
POLYSACCHARIDES
-------------
Carbohydrates means "hydrates of carbon".
These are poly-hydroxylated-aldehydes or poly-hydroxylated-ketones. The general formula is C-x(H-2O)-y
Aldehydes are compounds containing the carbonyl group -C=O as functional groupThe general formula is C-nH-2n-O, In aldehydes, the carbonyl carbon atom carries at least one H e.g.,
H
!
C=O
!
H
Formaldehyde
CH-3
!
C=O
!
H
Acetaldehyde
Ketones also have the same general formula C-nH-2nO but, the carbonyl atom does not carry any H atoms, but it is attached to two alkyl or aryl groups
CH-3
!
C=O
!
CH-3
It is Dimethyl ketone or Acetone. Its IUPAC name is Propanone
Carbohydrates are classified as:
Monosaccharides
Oligosaccharides
Polysaccharides
Monohydrates may be represented as follows
H
!
C=O
!
(H-C-OH)-n
!
CH-2OH
A polyhdroxy aldehyde
CH-2OH
!
C=O
!
(H-C-OH)-n
!
CH-2OH
A polyhdroxy ketone
Monosaccharides are named as follows.
1. The calss name of monosaccharides begins with the prefix 'aldo' for polyhydroxy aldehydes and "keto' for polyhydroxy ketones.
2. the name ends with suffix 'ose".
3. In between prefix and suffix, the number of carbon atoms (i.e. di, tri, tetr etc.) is inserted.
Examples
H
!
C=O
!
(H-C-OH)
!
CH-2OH
Aldotriose - (A polyhdroxy aldehyde)
CH-2OH
!
C=O
!
CH-2OH
Ketotriose - (A polyhdroxy ketone )
Reducing and Nonreducing Sugars
Reducing sugars are easily oxidized to give carboxylic acid.
They reduce
(i) Tollens reagent (an ammoniacal solution of silver nitrate) to shiny silver mirror.
(ii) Fehling's solution (an acqueous solution of cupric iron and tartrate salts) to red precipitate of cuprous oxide, and
(iii) Benedict's reagent (an alkaline solution containing a cupric citrate complex) to red precipitate of curous oxide)
---------------------------------------------
JEE Question 2007 Paper II
STATEMENT.1: Glucose gives a reddish brown precipitate with Fehling’s solution.
Because
STATEMENT.2: Reaction of glucose with Fehling’s solution gives CuO and gluconic acid.
(A) Statement.1 is True, Statement.2 is True; Statement.2 is a correct explanation for Statement.1.
(B) Statement.1 is True, Statement.2 is True; Statement.2 is NOT a correct explanation for Statement.1.
(C) Statement.1 is True, Statement.2 is False.
(D) Statement.1 is False, Statement.2 is True.
Answer: C.
Cu-2O is given not CuO.
--------------------------
Statement 1 is True. But statement 2 is false because Cu-2O Cuprous oxide is formed and not CuO.
---------------------------------------------
All aldoses are reducing sugars, but some ketoses are reducing sufars as well. For example, fructose (a ketose) reduces Tollens reagent. This occurs because fructose is readily isomerized to an aldose in basic solution.
A set of questions on this chapter posted in
www.iit-jee-chemistry-ps.blogspot.com
Carbohydrates:
Classification;
mono and di-saccharides (glucose and sucrose);
Oxidation, reduction,
glycoside formation and hydrolysis of sucrose.
--------------
Main Topics Covered in the TMH Book
MONOSACCHARIDES
DISACCHARIDES
POLYSACCHARIDES
-------------
Carbohydrates means "hydrates of carbon".
These are poly-hydroxylated-aldehydes or poly-hydroxylated-ketones. The general formula is C-x(H-2O)-y
Aldehydes are compounds containing the carbonyl group -C=O as functional groupThe general formula is C-nH-2n-O, In aldehydes, the carbonyl carbon atom carries at least one H e.g.,
H
!
C=O
!
H
Formaldehyde
CH-3
!
C=O
!
H
Acetaldehyde
Ketones also have the same general formula C-nH-2nO but, the carbonyl atom does not carry any H atoms, but it is attached to two alkyl or aryl groups
CH-3
!
C=O
!
CH-3
It is Dimethyl ketone or Acetone. Its IUPAC name is Propanone
Carbohydrates are classified as:
Monosaccharides
Oligosaccharides
Polysaccharides
Monohydrates may be represented as follows
H
!
C=O
!
(H-C-OH)-n
!
CH-2OH
A polyhdroxy aldehyde
CH-2OH
!
C=O
!
(H-C-OH)-n
!
CH-2OH
A polyhdroxy ketone
Monosaccharides are named as follows.
1. The calss name of monosaccharides begins with the prefix 'aldo' for polyhydroxy aldehydes and "keto' for polyhydroxy ketones.
2. the name ends with suffix 'ose".
3. In between prefix and suffix, the number of carbon atoms (i.e. di, tri, tetr etc.) is inserted.
Examples
H
!
C=O
!
(H-C-OH)
!
CH-2OH
Aldotriose - (A polyhdroxy aldehyde)
CH-2OH
!
C=O
!
CH-2OH
Ketotriose - (A polyhdroxy ketone )
Reducing and Nonreducing Sugars
Reducing sugars are easily oxidized to give carboxylic acid.
They reduce
(i) Tollens reagent (an ammoniacal solution of silver nitrate) to shiny silver mirror.
(ii) Fehling's solution (an acqueous solution of cupric iron and tartrate salts) to red precipitate of cuprous oxide, and
(iii) Benedict's reagent (an alkaline solution containing a cupric citrate complex) to red precipitate of curous oxide)
---------------------------------------------
JEE Question 2007 Paper II
STATEMENT.1: Glucose gives a reddish brown precipitate with Fehling’s solution.
Because
STATEMENT.2: Reaction of glucose with Fehling’s solution gives CuO and gluconic acid.
(A) Statement.1 is True, Statement.2 is True; Statement.2 is a correct explanation for Statement.1.
(B) Statement.1 is True, Statement.2 is True; Statement.2 is NOT a correct explanation for Statement.1.
(C) Statement.1 is True, Statement.2 is False.
(D) Statement.1 is False, Statement.2 is True.
Answer: C.
Cu-2O is given not CuO.
--------------------------
Statement 1 is True. But statement 2 is false because Cu-2O Cuprous oxide is formed and not CuO.
---------------------------------------------
All aldoses are reducing sugars, but some ketoses are reducing sufars as well. For example, fructose (a ketose) reduces Tollens reagent. This occurs because fructose is readily isomerized to an aldose in basic solution.
A set of questions on this chapter posted in
www.iit-jee-chemistry-ps.blogspot.com
Thursday, August 9, 2007
TMH-JEE-book-chapters Ch.32 Amino Acids
JEE Syllabus
Amino acids and peptides:
General structure (only primary structure for peptides) and
physical properties.
-----------------
Main Topics Covered in the TMH Book
AMINO ACIDS
PEPTIDE LINKAGE
---------------
amino acids are organic compounds containing both an amino group (NH2) and carboxylic group (COOH). They are represented by the general formula:
R
|
C-COOH
|
NH2
Essential amino acids
These amino acids are required by the body but are not made by our bodies. hence they must be supplied in diets.
Valine
Leucine
Isoleucine
Phenylalanine
Methionine
Trptophan
threonine
Lysine
Agrinine
L-Family of Amino Acids
With the exception of glycine, all other α amino acids have chiral carbon atom and have two optically active isomers.
However all naturally occurring amino acids belong to L series which have -NH2 group on the left.
Structure of Amino acids
amino acids exist as dipolar ion called a zwitter ion.
i) when an acid is added to an amino acid-COO- accepts this proton and therefore the basic character is due to -COO-group.
ii) When an alkali is added to amino acid -NH3+ group releases the proton and therefore acidic character is due to -NH3+ group.
Peptide
peptides are compounds formed by the condensation of two or more same or different α amino acids. The condensation occurs between amino acids with the elimination of water. In this case,the carboxyl group of one amino acid and amine group of another amino acid gets condensed with the elimination of water molecule. The resulting C-N linkage is called peptide linkage. The bond of C with O becomes a double bond.
The formation of peptide can be between two amino acid molecules or the number can go on until a single molecule containing several hundred thousands of aminoacids is formed.
Proteins
Structurally, proteins are long polymers of amino acids linked by peptide bonds
There is a question is about optical activity of amino acids in TMH JEE book. Which amino acid does not exhibity optical activity?
I did a google search on optical activity of organic chemical compounds and I got the following entries.
http://en.wikibooks.org/wiki/Organic_Chemistry/Chirality/Optical_activity
http://www.chemguide.co.uk/organicprops/aminoacids/background.html
Optical activity
If you look yet again at the general formula for an amino acid, you will see that (apart from glycine, 2-aminoethanoic acid) the carbon at the centre of the structure has four different groups attached. In glycine, the "R" group is another hydrogen atom.
This is equally true if you draw the structure of the zwitterion instead of this simpler structure.
Because of these four different groups attached to the same carbon atom, amino acids (apart from glycine) are chiral.
Hence the amino acid Glycine does not exhibit optical acivity. This is the answer to the question.
------------------
A set of questions for practice on this chapter posted in
www.iit-jee-chemistry-ps.blogspot.com
Amino acids and peptides:
General structure (only primary structure for peptides) and
physical properties.
-----------------
Main Topics Covered in the TMH Book
AMINO ACIDS
PEPTIDE LINKAGE
---------------
amino acids are organic compounds containing both an amino group (NH2) and carboxylic group (COOH). They are represented by the general formula:
R
|
C-COOH
|
NH2
Essential amino acids
These amino acids are required by the body but are not made by our bodies. hence they must be supplied in diets.
Valine
Leucine
Isoleucine
Phenylalanine
Methionine
Trptophan
threonine
Lysine
Agrinine
L-Family of Amino Acids
With the exception of glycine, all other α amino acids have chiral carbon atom and have two optically active isomers.
However all naturally occurring amino acids belong to L series which have -NH2 group on the left.
Structure of Amino acids
amino acids exist as dipolar ion called a zwitter ion.
i) when an acid is added to an amino acid-COO- accepts this proton and therefore the basic character is due to -COO-group.
ii) When an alkali is added to amino acid -NH3+ group releases the proton and therefore acidic character is due to -NH3+ group.
Peptide
peptides are compounds formed by the condensation of two or more same or different α amino acids. The condensation occurs between amino acids with the elimination of water. In this case,the carboxyl group of one amino acid and amine group of another amino acid gets condensed with the elimination of water molecule. The resulting C-N linkage is called peptide linkage. The bond of C with O becomes a double bond.
The formation of peptide can be between two amino acid molecules or the number can go on until a single molecule containing several hundred thousands of aminoacids is formed.
Proteins
Structurally, proteins are long polymers of amino acids linked by peptide bonds
There is a question is about optical activity of amino acids in TMH JEE book. Which amino acid does not exhibity optical activity?
I did a google search on optical activity of organic chemical compounds and I got the following entries.
http://en.wikibooks.org/wiki/Organic_Chemistry/Chirality/Optical_activity
http://www.chemguide.co.uk/organicprops/aminoacids/background.html
Optical activity
If you look yet again at the general formula for an amino acid, you will see that (apart from glycine, 2-aminoethanoic acid) the carbon at the centre of the structure has four different groups attached. In glycine, the "R" group is another hydrogen atom.
This is equally true if you draw the structure of the zwitterion instead of this simpler structure.
Because of these four different groups attached to the same carbon atom, amino acids (apart from glycine) are chiral.
Hence the amino acid Glycine does not exhibit optical acivity. This is the answer to the question.
------------------
A set of questions for practice on this chapter posted in
www.iit-jee-chemistry-ps.blogspot.com
Wednesday, August 8, 2007
TMH JEE Org. Chemistry CH 33 Polymers
JEE syllabus
Properties and uses of some important polymers:
Natural rubber,
cellulose,
nylon,
teflon and
PVC.
-----------------
Main Topics Covered in the TMH Book
POLYMERS
SOME EXAMPLES OF STEP-GROWTH POLYMERS
---------------
A polymer is a large molecule built by repetitive binding together of many small units called monomers.
Homopolymer: A polymer derived from a single repeating monomer. Only one type of monomer will have repetitive binding and a large molecule appears.
Copolymer: When two or more different monomers bind together in a repetitive manner and give rise to a large polymer, it is called copolymer.
Classification of Polymers
Classification based on source:
Natural and synthetic
Classification based on structure:
1.Linear polymers
2. Branched chain polymers
3. Cross linked polymers
Classification based on molecular forces and physical properties
1. Elastomers
2. Fibres
3. Thermoplastics
4. Thermosetting polymers
Classification based on mode of synthesis:
1. addition polymers
2. Condensation polymers
Methods of Polymerisation
Synthetic polymerisation processes are categorised as Chain growth and step growth polymerisation.
Chain growth polymerisation: Also called addition polymerisation.
In this process, the combination of monomers does not result in elimination of some by product molecules. The process is initiated by by a free radical, a cation or an anion and once initiated, the process gets repeated as a chain reaction as the process produces bigger and bigger active molecules.
Illustrative Model
1. Initiator --> I* a reactive species
2. I* + M (monomer) --> IM* (bigger reactive species)
3. IM* + M --> IMM*
4. IMM* + M --> IMMM*
The chain stops when the active end reacts with a species giving a molecule without the reactive end.
Many vinyl polymers (Vinyl indicates compounds having double bonds) are formed by chain growth polymerisation (chain reaction polymerisation).
Step Growth polymerisation: Also called as condensation polymerisation
In condensation polymerisation, two or more different monomers combine together and in this process of combination elimination of simple molecules like water, ammonia, hydrogen chloride etc. takes place. So there is a condensation in this process of polymerisation.
In this polymerisation generally the monomers contain two functional monomers (difunctional monomers). In this process, the polymerisation takes place step by step.
Illustratitive model
A + B --> A-B
A-B + A --> A-B-A
A-B-A + B --> A-B-A-B
It can also be
A-B + A-B --> A-B-A-B
Properties and uses Natural rubber
Rubber is a naturally occuring polymer. It is obtained as latex from rubber trees. It is highly elastic.
It is a polymer of isoprene (2-methyl buta-1,3-diene)
In natural rubber, about 11,000 to 20,000 isoprene units are linked together in a chain like arrangement.
Natural rubber is a thermoplastic. It becomes soft and sticky when heated. It is not hard and tough.t The properties can be modified and improved by the process of vulcanization.
Properties and uses cellulose
Properties and uses nylon
The monomer of nylon 6 is caprolactum.
fabrics, ropes and tyre cords are prepared using nylon 6.
For nylon 66, the monomers are hexamethylenediamine and adipic acid.
Bristles for brushes, and textile sheets are made using nylon 66
Properties and uses teflon
It is an addition polymer of tetrafluoroethylene.
nF2C=CF2 under heat and pressure (-F2C-CF2-)n
The double bond breaks and gets ready for bonding with a carbon on either side and the polymerisation takes place.
It is a tough material and is resistant towards heat, action of chemicals such as acids and bases. It is bad conductor of electricity.
Properties and uses PVC.
PVC is polyvinyl chloride
Its monomer is vinyl chloride. CH2=CHCl
PVC is prepared by heating vinyl chloride in an inert solvent in the presence of peroxides ( for instance, dibenboyl peroxide)
The double bond breaks and becomes ready bonding to carbon on either side and polymerisation takes place.
PVC is hard horny material. It is a thermoplastic polymer andits plasticity can be increased by the addition of plasticizer usch n-butylphthalate.
PVC is used in the manufacture of rain coats, hand bags, curtain clothes,and toys.
It is also used in articial flooring, as an insulating material in electric wires and for making gramophone records.
----------------------------------
A set of questions on this chapter posted in
www.iit-jee-chemistry-ps.blogspot.com
Properties and uses of some important polymers:
Natural rubber,
cellulose,
nylon,
teflon and
PVC.
-----------------
Main Topics Covered in the TMH Book
POLYMERS
SOME EXAMPLES OF STEP-GROWTH POLYMERS
---------------
A polymer is a large molecule built by repetitive binding together of many small units called monomers.
Homopolymer: A polymer derived from a single repeating monomer. Only one type of monomer will have repetitive binding and a large molecule appears.
Copolymer: When two or more different monomers bind together in a repetitive manner and give rise to a large polymer, it is called copolymer.
Classification of Polymers
Classification based on source:
Natural and synthetic
Classification based on structure:
1.Linear polymers
2. Branched chain polymers
3. Cross linked polymers
Classification based on molecular forces and physical properties
1. Elastomers
2. Fibres
3. Thermoplastics
4. Thermosetting polymers
Classification based on mode of synthesis:
1. addition polymers
2. Condensation polymers
Methods of Polymerisation
Synthetic polymerisation processes are categorised as Chain growth and step growth polymerisation.
Chain growth polymerisation: Also called addition polymerisation.
In this process, the combination of monomers does not result in elimination of some by product molecules. The process is initiated by by a free radical, a cation or an anion and once initiated, the process gets repeated as a chain reaction as the process produces bigger and bigger active molecules.
Illustrative Model
1. Initiator --> I* a reactive species
2. I* + M (monomer) --> IM* (bigger reactive species)
3. IM* + M --> IMM*
4. IMM* + M --> IMMM*
The chain stops when the active end reacts with a species giving a molecule without the reactive end.
Many vinyl polymers (Vinyl indicates compounds having double bonds) are formed by chain growth polymerisation (chain reaction polymerisation).
Step Growth polymerisation: Also called as condensation polymerisation
In condensation polymerisation, two or more different monomers combine together and in this process of combination elimination of simple molecules like water, ammonia, hydrogen chloride etc. takes place. So there is a condensation in this process of polymerisation.
In this polymerisation generally the monomers contain two functional monomers (difunctional monomers). In this process, the polymerisation takes place step by step.
Illustratitive model
A + B --> A-B
A-B + A --> A-B-A
A-B-A + B --> A-B-A-B
It can also be
A-B + A-B --> A-B-A-B
Properties and uses Natural rubber
Rubber is a naturally occuring polymer. It is obtained as latex from rubber trees. It is highly elastic.
It is a polymer of isoprene (2-methyl buta-1,3-diene)
In natural rubber, about 11,000 to 20,000 isoprene units are linked together in a chain like arrangement.
Natural rubber is a thermoplastic. It becomes soft and sticky when heated. It is not hard and tough.t The properties can be modified and improved by the process of vulcanization.
Properties and uses cellulose
Properties and uses nylon
The monomer of nylon 6 is caprolactum.
fabrics, ropes and tyre cords are prepared using nylon 6.
For nylon 66, the monomers are hexamethylenediamine and adipic acid.
Bristles for brushes, and textile sheets are made using nylon 66
Properties and uses teflon
It is an addition polymer of tetrafluoroethylene.
nF2C=CF2 under heat and pressure (-F2C-CF2-)n
The double bond breaks and gets ready for bonding with a carbon on either side and the polymerisation takes place.
It is a tough material and is resistant towards heat, action of chemicals such as acids and bases. It is bad conductor of electricity.
Properties and uses PVC.
PVC is polyvinyl chloride
Its monomer is vinyl chloride. CH2=CHCl
PVC is prepared by heating vinyl chloride in an inert solvent in the presence of peroxides ( for instance, dibenboyl peroxide)
The double bond breaks and becomes ready bonding to carbon on either side and polymerisation takes place.
PVC is hard horny material. It is a thermoplastic polymer andits plasticity can be increased by the addition of plasticizer usch n-butylphthalate.
PVC is used in the manufacture of rain coats, hand bags, curtain clothes,and toys.
It is also used in articial flooring, as an insulating material in electric wires and for making gramophone records.
----------------------------------
A set of questions on this chapter posted in
www.iit-jee-chemistry-ps.blogspot.com
TMH JEE Chemistry Chapters - List
Organic Chemistry chapter names TMH IIT JEE Chemistry
19. Hybridization, Isomerism
20. Inductive and Resonance Effects
21. Alkanes
22. Alkenes
23. Alkynes
24. Benzene
25. Alcohols
26. Alkyl and Aryl Halides
27. Aldehydes and Ketones
28. Carboxylic Acids
29. Phenols
30. Amines
31. Carbohydrates
32. Aminoacids and Peptides
33. Polymers
34. Exercises in Organic Chemistry
19. Hybridization, Isomerism
20. Inductive and Resonance Effects
21. Alkanes
22. Alkenes
23. Alkynes
24. Benzene
25. Alcohols
26. Alkyl and Aryl Halides
27. Aldehydes and Ketones
28. Carboxylic Acids
29. Phenols
30. Amines
31. Carbohydrates
32. Aminoacids and Peptides
33. Polymers
34. Exercises in Organic Chemistry
Thursday, August 2, 2007
Virtual Textbook of Organic Chemistry
http://www.cem.msu.edu/~reusch/VirtualText/intro1.htm#info
contents
Functional Group Reactions
Alkanes
Combustion
Substitution (of H by halogen)
Practice Problems
Alkenes
Electrophilic Additions
Strong Brønsted Acids
Lewis Acids (non-Proton Electrophiles)
Electrophilic Halogen Reagents
Other Electrophilic Reagents
Reduction
Oxidation
Radical Additions
Allylic Substitution
Practice Problems
Dienes
Addition Reactions
Diels-Alder Cycloaddition
Practice Problems
Alkynes
Addition Reactions
Hydrogenation
Electrophiles
Hydration & Tautomerism
Hydroboration
Nucleophilile Addition & Reduction
Acidity of Terminal Alkynes (Substitution of H)
Practice Problems
Alkyl Halides
General Reactivity
Substitution(of X)
SN2 Mechanism
SN1 Mechanism
Elimination (of HX)
Summary of Substiution vs. Elimination
Substitution by Metals
Elimination Reactions of Dihalides
Practice Problems
Alcohols
Nomenclature
Reactions of Alcohols
Substitution of the Hydroxyl H
Substitution of the Hydroxyl Group
Elimination of Water
Oxidation of Alcohols
Reactions of Phenols
Acidity of Phenols
Ring Substitution of Phenols
Oxidation to Quinones
Practice Problems
Ethers
Nomenclature
Preparation of Ethers
Reactions of Ethers
Acid Cleavage
Peroxide Formation
Epoxide Reactions
Practice Problems
Thiols & Sulfides
Sulfur Analogs of Alcohols & Ethers
Benzene & Derivatives
Electrophilic Substitution
A Substitution Mechanism
Reactions of Substituted Benzenes
Reaction Characteristics
Reactions of Disubstituted Rings
Reactions of Substituent Groups
Nucleophilic Substitution, Elimination & Addition Reactions
Practice Problems
Amines
Nomenclature & Structure
Properties of Amines
Boiling Point & Solubility
Basicity of Nitrogen Compounds
Acidity of Nitrogen Compounds
Important Reagent Bases
Reactions of Amines
Electrophilic Substitution at Nitrogen
Preparation of 1º-Amines
Preparation of 2º & 3º-Amines
Practice Problems
Reactions with Nitrous Acid
Reactions of Aryl Diazonium Intermediates
Elimination Reactions of Amines
Oxidation States of Nitrogen
Practice Problems
Phosphines
Phosphorus Analogs of Amines
Aldehydes & Ketones
Nomenclature of Aldehydes & Ketones
Occurrence of Aldehydes & Ketones
Natural Products
Synthetic Preparation
Properties of Aldehydes & Ketones
Reversible Addition Reactions
Hydration & Hemiacetal Formation
Acetal Formation
Imine Formation
Enamine Formation
Cyanohydrin Formation
Irreversible Addition Reactions
Complex Metal Hydrides
Organometallic Reagents
Carbonyl Group Modification
Wolff-Kishner Reduction
Clemmensen Reduction
Hydrogenolysis of Thioacetals
Oxidations
Reactions at the α-Carbon
Mechanism of Electrophilic α-Substitution
The Aldol Reaction
Ambident Enolate Anions
Alkylation of Enolate Anions
Practice Problems
Carboxylic Acids
Nomenclature of Carboxylic Acids
Natural Products
Related Derivatives
Physical Properties
Acidity
Preparation of Carboxylic Acids
Reactions of Carboxylic Acids
Salt Formation
Substitution of Hydroxyl Hydrogen
Substitution of the Hydroxyl Group
Reduction & Oxidation
Practice Problems
Carboxylic Derivatives
Physical Properties
Nomenclature
Reactions of Carboxylic Acid Derivatives
Acyl Group Substitution
Mechanism
Reduction
Catalytic Reduction
Metal Hydride Reduction
Diborane Reduction
Reaction with Organometallic Reagents
Practice Problems
Reactions at the α Carbon
Acidity of α C–H
The Claisen Condensation
Synthesis Applications
Practice Problems
contents
Functional Group Reactions
Alkanes
Combustion
Substitution (of H by halogen)
Practice Problems
Alkenes
Electrophilic Additions
Strong Brønsted Acids
Lewis Acids (non-Proton Electrophiles)
Electrophilic Halogen Reagents
Other Electrophilic Reagents
Reduction
Oxidation
Radical Additions
Allylic Substitution
Practice Problems
Dienes
Addition Reactions
Diels-Alder Cycloaddition
Practice Problems
Alkynes
Addition Reactions
Hydrogenation
Electrophiles
Hydration & Tautomerism
Hydroboration
Nucleophilile Addition & Reduction
Acidity of Terminal Alkynes (Substitution of H)
Practice Problems
Alkyl Halides
General Reactivity
Substitution(of X)
SN2 Mechanism
SN1 Mechanism
Elimination (of HX)
Summary of Substiution vs. Elimination
Substitution by Metals
Elimination Reactions of Dihalides
Practice Problems
Alcohols
Nomenclature
Reactions of Alcohols
Substitution of the Hydroxyl H
Substitution of the Hydroxyl Group
Elimination of Water
Oxidation of Alcohols
Reactions of Phenols
Acidity of Phenols
Ring Substitution of Phenols
Oxidation to Quinones
Practice Problems
Ethers
Nomenclature
Preparation of Ethers
Reactions of Ethers
Acid Cleavage
Peroxide Formation
Epoxide Reactions
Practice Problems
Thiols & Sulfides
Sulfur Analogs of Alcohols & Ethers
Benzene & Derivatives
Electrophilic Substitution
A Substitution Mechanism
Reactions of Substituted Benzenes
Reaction Characteristics
Reactions of Disubstituted Rings
Reactions of Substituent Groups
Nucleophilic Substitution, Elimination & Addition Reactions
Practice Problems
Amines
Nomenclature & Structure
Properties of Amines
Boiling Point & Solubility
Basicity of Nitrogen Compounds
Acidity of Nitrogen Compounds
Important Reagent Bases
Reactions of Amines
Electrophilic Substitution at Nitrogen
Preparation of 1º-Amines
Preparation of 2º & 3º-Amines
Practice Problems
Reactions with Nitrous Acid
Reactions of Aryl Diazonium Intermediates
Elimination Reactions of Amines
Oxidation States of Nitrogen
Practice Problems
Phosphines
Phosphorus Analogs of Amines
Aldehydes & Ketones
Nomenclature of Aldehydes & Ketones
Occurrence of Aldehydes & Ketones
Natural Products
Synthetic Preparation
Properties of Aldehydes & Ketones
Reversible Addition Reactions
Hydration & Hemiacetal Formation
Acetal Formation
Imine Formation
Enamine Formation
Cyanohydrin Formation
Irreversible Addition Reactions
Complex Metal Hydrides
Organometallic Reagents
Carbonyl Group Modification
Wolff-Kishner Reduction
Clemmensen Reduction
Hydrogenolysis of Thioacetals
Oxidations
Reactions at the α-Carbon
Mechanism of Electrophilic α-Substitution
The Aldol Reaction
Ambident Enolate Anions
Alkylation of Enolate Anions
Practice Problems
Carboxylic Acids
Nomenclature of Carboxylic Acids
Natural Products
Related Derivatives
Physical Properties
Acidity
Preparation of Carboxylic Acids
Reactions of Carboxylic Acids
Salt Formation
Substitution of Hydroxyl Hydrogen
Substitution of the Hydroxyl Group
Reduction & Oxidation
Practice Problems
Carboxylic Derivatives
Physical Properties
Nomenclature
Reactions of Carboxylic Acid Derivatives
Acyl Group Substitution
Mechanism
Reduction
Catalytic Reduction
Metal Hydride Reduction
Diborane Reduction
Reaction with Organometallic Reagents
Practice Problems
Reactions at the α Carbon
Acidity of α C–H
The Claisen Condensation
Synthesis Applications
Practice Problems
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