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Starter - complete the following scheme giving all Formula Ethyl ethanoate Formula? Ethanoyl chloride Formula? Ethanoic acid CH 3 COOH CH 3 COCl CH 3 COOC 2 H 5 Reagents? C 2 H 5 OH + Conc H 2 SO 4 Reagents? H+ CH 3 COOH + C 2 H 5 OH OH- C 2 H 5 NH 2 / ethanol salt + ethanol CH 3 COO - + C 2 H 5 OH ethanamide CH 3 CONH 2 NH 3 / ethanol N-ethylethanamide CH 3 CONH 2 C 2 H 5

O NH 2 C R Amides Named......anamide O NH 2 CCH 3 ethanamide O NH 2 CH methanamide O NH 2 CCH 3 CH 2 propanamide

Reactions of Amides Amides are formed by : Substitution of acid derivates 1.Acid chloride and ammonia O NH 2 CCH 3 O + NH 4 Cl CCH 3 Cl + NH 3 ethanoyl chloride + ammonia ethanamide + ammonium chloride

1.Ester and ammonia O NH 2 CCH 3 O + CH 3 OH CCH 3 O + NH 3 CH 3 Methyl ethanoate + ammonia ethanamide + methanol

Reactions of amides 1.Hydrolysis in Acidic conditions occurs with heating O NH 2 CCH 3 + H 3 O + O OH CCH 3 + NH 4 + ethanamide + acid ethanoic acid + ammonium ion heat

Reactions of amides 2. Hydrolysis occurs in Basic conditions with heat O NH 2 CCH 3 + OH - O O - CCH 3 + NH 3 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 CH 2 CH 2 CH 2 CH 2 C O OH hexanedioic acid H H N CH 2 CH 2 (CH 2 ) 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 CH 2 CH 2 (CH 2 ) 3 CH 2 N H H 1,6 diaminohexane OH C HO O CH 2 CH 2 CH 2 CH 2 C O Water removed means a condensation reaction amide link This reaction occurs at each end to produce long chains of 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 C 6 H 6 CO benzene -1,4-dicarboxylic + acid ethan-1,2-diol OH H+O (CH 2 ) 2 OH H 2 O removed means a condensation reaction …HOOC C 6 H 6 CO (CH 2 ) 2 OH.. O When many of these molecules are joined together the common polymer Terylene is formed Terylene

Amino Acids and Polymers

Amino Acids Amino acids have two functional groups: A carboxylic acid group (COOH) A carboxylic acid group (COOH) An amino group NH 2 An amino group NH 2

Amino Acid Structure Naturally occurring amino acids have the general 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, CH 3, SH etc

Common Amino Acids 1. The amino acid glycine (aminoethanoic acid) has an H as the R group. Draw it please Glycine HCH(NH 2 )COOH

Common Amino Acids 2. The amino acid alanine ( 2-aminopropanoic acid) has an CH 3 as the R group – draw this to. Alanine CH 3 CH(NH 2 )COOH The Carbon 2 atom is bonded to four different groups

Alanine CH 3 CH(NH 2 )COOH In alanine the Carbon 2 atom is bonded to four different groups these are:  One carboxylic acid group COOH  One amino group NH 2  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 decide which ones are optically active – mark the chiral carbon with an asterisk Task : Draw the following molecules and decide which ones are optically active – mark the chiral carbon with an asterisk 2 - chlorobutane 2 - methylpropanoic acid 3 – methylpentanal 2 - aminobutanoic acid

Polymers Two types of polymer:  Addition polymerisation  Condensation polymerisation

H C H H C H.. H C H H C H.. H C H H C H We 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

CH 3 C H H C H.. C H H C H.. C H H C H.. Changing the alkene monomer creates a new polymer CH 3 C H H C H.. C H H C H.. C H H C H.. Heat and a catalyst added CH 3 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.. C H H C H.. C H H C H.. C H H C H.. C H H C H.. 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 C H H C H

Natural Condensation Polymers Proteins 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 are formed by the condensation of a large number of amino acids. Small molecules called dipeptides and tripeptides are formed by the condensation 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? H2OH2O

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

CH 2 OH O H H OHOH OHOH HOHO H H OH H What’s this common natural monomer? OH CH 2 OH O H H OHOH OHOH O H H H H Many glucose monomers join together to form the natural polymer starch H 2 O removed means a condensation reaction glucose

What other polymers are made from many more glucose monomers?. Cellullose

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

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 1846 The process uses the nitric acid to convert the cellulose into cellulose nitrite and water: 2HNO 3 + C 6 H 10 O 5 → C 6 H 8 (NO 2 ) 2 O 5 + 2H 2 O

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