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Starter - complete the following scheme giving Starter - complete the following scheme giving all Formulaall Formula

Ethyl ethanoate

Formula?

Ethanoyl chloride

Formula?

Ethanoic acid

CH3COOH

CH3COCl

CH3COOC2H5

Reagents?C2H5OH

C2H5OH

+ Conc H2SO4

Reagents?

H+ CH3COOH + C2H5OH

OH-

C2H5NH2 /

ethanol

salt + ethanol

CH3COO- + C2H5OH

ethanamide

CH3CONH2

NH3 / ethanol

N-ethylethanamide

CH3CONH2C2H5

O

NH2

C R

Amides

Named ......anamide

O

NH2

CCH3

ethanamide

O

NH2

CH

methanamide

O

NH2

CCH3 CH2

propanamide

Reactions of Amides

Amides are formed by :

Substitution of acid derivates

1.Acid chloride and ammonia

O

NH2

CCH3

O

+ NH4Cl CCH3

Cl

+ NH3

ethanoyl chloride + ammonia ethanamide + ammonium chloride

1.Ester and ammonia

O

NH2

CCH3

O

+ CH3OH CCH3

O

+ NH3

CH3

Methyl ethanoate + ammonia ethanamide + methanol

Reactions of amides

1.Hydrolysis in Acidic conditions occurs with heating

O

NH2

CCH3 + H3O+

O

OH CCH3 + NH4

+

ethanamide + acid ethanoic acid + ammonium ion

heat

Reactions of amides

2. Hydrolysis occurs in Basic conditions with heat

O

NH2

CCH3 + OH-

O

O- CCH3 + NH3

ethanamide + base ethanoate ion + ammonia

heat

Chemical Properties of Amides

1. Amides are very weak bases they are neutral to indicators and are insoluble in hydrochloric acid (ie no salt forms)

2.They have relatively high boiling points due to the hydrogen bonding of the carbonyl oxygen of one amide with the Hydrogen on the Nitrogen atom of another amide

3. Smaller amides are soluble in water while larger ones are not

Synthetic condensation polymers

Polyamides

Polyamides can be made by combining a diamine and a dicarboxylic acid

Nylon 6,6 can be made into fibres to make pantyhose or in other forms gear wheels with tough properties

Nylon 6,6 is made from hexanedioic acid and 1,6 diaminohexane

C

HO

O

CH2CH2CH2CH2C

O

OH

hexanedioic acid

H

H

N CH2CH2(CH2)4 N

H

H

1,6 diaminohexane

Synthetic polymers

Polyamides

Nylon 6,6 is an example of a condensation polymer

hexanedioic acid

H

H

N CH2CH2(CH2)3CH2 N

H

H

1,6 diaminohexane

OH

C

HO

O

CH2CH2CH2CH2C

O

Water removed means a condensation reaction

amide link

This reaction occurs at each end to produce long chainsof these monomers joined by an amide link

One more condensation polymer –

polyesters

these are made from a diol and dicarboxylic acid

For example 1, 2 – ethandiol and benzene-1,4-dicarboxylic acid

HOOC C6H6 CO

benzene -1,4-dicarboxylic + acid

ethan-1,2-diol

OH H+ O (CH2)2 OH

H2O removed means a condensation reaction

…HOOC C6H6 C

O (CH2)2 OH ..

O

When many of these molecules are joined together the common polymer Terylene is formed

Terylene

Amino Acids and PolymersAmino Acids and Polymers

Amino AcidsAmino Acids

Amino acids have two functional groups:Amino acids have two functional groups:• A carboxylic acid group (COOH)A carboxylic acid group (COOH)• An amino group NHAn amino group NH22

Amino Acid StructureAmino Acid Structure

Naturally occurring amino acids have the Naturally occurring amino acids have the general structuregeneral structure

The amino group is attached to carbon 2 (known by biologists as the alpha (α) carbon) that is next to the carboxylic acid group these form the naturally occurring alpha (α) amino acids

R= H, CH3 , SH etc

Common Amino AcidsCommon Amino Acids

1.1. The amino acid glycine (aminoethanoic The amino acid glycine (aminoethanoic acid) has an H as the R group.acid) has an H as the R group.

Draw it pleaseDraw it please

Glycine

HCH(NH2)COOH

Common Amino AcidsCommon Amino Acids

2. The amino acid alanine ( 2-aminopropanoic 2. The amino acid alanine ( 2-aminopropanoic acid) has an CHacid) has an CH33 as the R group – draw this as the R group – draw this

to. to.

Alanine

CH3CH(NH2)COOH

The Carbon 2 atom is bonded to four different groups

Alanine

CH3CH(NH2)COOH

In alanine the Carbon 2 atom is bonded to four different groups these are:

One carboxylic acid group COOH

One amino group NH2

One hydrogen atom H

One methyl group

This means that alanine can form what type of isomerism?

Optical isomerism

Draw the structure of alanine and label the asymmetric carbon with a *

Now draw its optical isomer

Task : Draw the following molecules and Task : Draw the following molecules and decide which ones are optically active – decide which ones are optically active – mark the chiral carbon with an asteriskmark the chiral carbon with an asterisk

2 - chlorobutane2 - chlorobutane

2 - methylpropanoic acid2 - methylpropanoic acid

3 – methylpentanal3 – methylpentanal

2 - aminobutanoic acid2 - aminobutanoic acid

PolymersPolymers

Two types of polymer:Two types of polymer: Addition polymerisationAddition polymerisation Condensation polymerisationCondensation polymerisation

H

C

H

H

C

H

. .

H

C

H

H

C

H

. .

H

C

H

H

C

HWe can draw the ethene molecule with one of the bonds in the double bond as two electrons so it looks like this

The ethene

monomer

Addition Polymers

CH3

C

H

H

C

H

. .

CH3

C

H

H

C

H

. .

CH3

C

H

H

C

H

. .

Changing the alkene

monomer creates a

new polymer

CH3

C

H

H

C

H

. .

CH3

C

H

H

C

H

. .

CH3

C

H

H

C

H

. .

Heat and a catalyst added

CH3

C

H

H

C

H

Propene monomer

Makes polypropene

Aka polypropylene

Used in plastic coke bottles and polar fleece

Repeating monomer unit

Cl

C

H

H

C

H

. .

Cl

C

H

H

C

H

. .

Cl

C

H

H

C

H

. .

Cl

C

H

H

C

H

. .

Cl

C

H

H

C

H

. .

Cl

C

H

H

C

H

. .

Heat and a catalyst added

3 chloroethene (aka vinyl chloride) monomers

Repeating monomer unit Polyvinylchloride

Polymer

Aka PVC used in many manufactured plastics

Changing the side chain of the monomer in the reaction gives different polymers ie

C

H

H

C

H

Cl

C

H

H

C

H

Cl

C

H

H

C

H

Cl

Natural Condensation PolymersNatural Condensation PolymersProteins are one example of a biologically important polymer. They are found in all parts of the body as they are the structural components of skin, muscle and hair, while others are enzymes that catalyse reactions in the body.

Why are they called condensation polymers?

Proteins Proteins

Proteins are formed by the condensation of Proteins are formed by the condensation of a large number of amino acids.a large number of amino acids.

Small molecules called dipeptides and Small molecules called dipeptides and tripeptides are formed by the condensation tripeptides are formed by the condensation of 2 and 3 amino acids respectively of 2 and 3 amino acids respectively

If 2 amino acids condense to form a dipeptide there are two distinct structures – draw them and label the special link

OR

Peptide link

What other product is released in the reaction? H2O

When many hundreds of amino acids continue linking by these condensation reactions proteins are formed

CH2OH

OH

H

OH

OHHO

H

H

OH

H

What’s this common natural monomer?

OH

CH2OH

O H

H

OH

OH O

H

H

H

H

Many glucose monomers join together to form the natural polymer starch

H2O removed means a condensation reaction

glucose

What other polymers are made from many more glucose monomers?

.

Cellullose

Christian Friedrich Schönbein, a German-Swiss chemist, discovered a stable way of making nitocellulose around 1846. As he was working in the kitchen of his home in Basle, he spilled a bottle of concentrated nitric acid on the kitchen table.

He reached for the nearest cloth, a cotton apron, and wiped it up. He hung the apron on the stove door to dry, and as soon as it was dry there was a flash as the apron exploded

His preparation method was the first to be widely imitated — one part of fine cotton wool to be immersed in fifteen parts of an equal blend of sulfuric and nitric acids.

After two minutes the cotton was removed and washed in cold water to set the esterification level and remove all acid residue. It was then slowly dried at a temperature below 100°C.

Schönbein collaborated with the Frankfurt professor Rudolf Böttger, who had discovered the process independently in the same year.

By a strange coincidence there was even a third chemist, the Braunschweig professor F. J. Otto, who had also produced guncotton in 1846The process uses the nitric acid to convert the cellulose into cellulose nitrite and water:

2HNO3+ C6H10O5 → C6H8(NO2)2O5 + 2H2O

Nitrocellulose(cellulose nitrate)

Various types smokeless gun powder consisting mainly of nitrocellulose

Turn to page 234 in the lab book – Natural Polymers

Complete the polymer question sheet