Chapter25ISM

Chapter25ISM - CHAPTER 25 SYNTHETIC AND NATURAL ORGANIC...

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CHAPTER 25 SYNTHETIC AND NATURAL ORGANIC POLYMERS Problem Categories Biological : 25.19, 25.20, 25.21, 25.35, 25.36, 25.39, 25.41, 25.43, 25.44. Conceptual : 25.22, 25.27, 25.28, 25.29, 25.30, 25.32, 25.34, 25.37, 25.38, 25.40, 25.42, 25.45. Descriptive : 25.7, 25.9, 25.10, 25.31, 25.33. Difficulty Level Easy : 25.9, 25.21, 25.22, 25.29, 25.31, 25.44. Medium : 25.7, 25.8, 25.10, 25.11, 25.12, 25.19, 25.20, 25.28, 25.30, 25.32, 25.33, 25.35, 25.36, 25.37, 25.38, 25.39, 25.40, 25.42, 25.46, 25.47. Difficult : 25.27, 25.34, 25.41, 25.43, 25.45, 25.48, 25.49, 25.50. 25.7 The reaction is initiated be a radical, R R + CF 2 = CF 2 R CF 2 CF 2 The product is also a radical, and the reaction continues. R CF 2 CF 2 + CF 2 = CF 2 R CF 2 CF 2 CF 2 CF 2 etc. .. 25.8 The repeating structural unit of the polymer is: Does each carbon atom still obey the octet rule? 25.9 The general reaction is a condensation to form an amide. The polymer chain looks like: Note that both reactants are disubstituted benzene derivatives with the substituents in the para or 1,4 positions. C H H C H Cl C H H C n R OH NH 2 R' H 2 O RC O O + + CN H C NH C C C NH NH O O O O
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CHAPTER 25: SYNTHETIC AND NATURAL ORGANIC POLYMERS 688 25.10 Polystyrene is formed by an addition polymerization reaction with the monomer, styrene, which is a phenyl substituted ethylene. The structures of styrene and polystyrene are shown in Table 25.1 of your text. 25.11 The structures are as shown. 25.12 The structures are shown. (a) (b) 25.19 alanylglycine and glycylalanine are shown in Figure 25.8. 25.20 The main backbone of a polypeptide chain is made up of the α carbon atoms and the amide group repeating alternately along the chain. C H R 1 C O N H C R 2 H C O N H amide groups α carbon α carbon For each R group shown above, substitute the distinctive side groups of the two amino acids. Their are two possible dipeptides depending on how the two amino acids are connected, either glycine lysine or lysine glycine. The structures of the dipeptides are: (a) CF 2 CH 2 (b) NH 2 H 2 N CO 2 H HO 2 C H 2 CC HC H 2 C O HO 2 2 2 2 2 2 NH 2 CH H 2 N H C O NH CH CH 2 C O OH CH 2 CH 2 CH 2 NH 2 glycine lysine
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CHAPTER 25: SYNTHETIC AND NATURAL ORGANIC POLYMERS 689 and 25.21 The structure of the polymer is: 25.22 The rate increases in an expected manner from 10 ° C to 30 ° C and then drops rapidly. The probable reason for this is the loss of catalytic activity of the enzyme because of denaturation at high temperature. 25.27 There are two common structures for protein molecules, an α helix and a β− pleated sheet. The α− helical structure is stabilized by intramolecular hydrogen bonds between the NH and CO groups of the main chain, giving rise to an overall rodlike shape. The CO group of each amino acid is hydrogen-bonded to the NH group of the amino acid that is four residues away in the sequence. In this manner all the main-chain CO and NH groups take part in hydrogen bonding. The β− pleated structure is like a sheet rather than a rod. The polypeptide chain is almost fully extended, and each chain forms many intermolecular hydrogen bonds with adjacent chains. In general, then, the hydrogen bonding is responsible for the three dimensional geometry of the protein molecules.
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Chapter25ISM - CHAPTER 25 SYNTHETIC AND NATURAL ORGANIC...

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