Question: Circle the isoprene units in each of

> Propose a mechanism for the acid-catalyzed hydrolysis of PET to regenerate the monomers terephthalic acid and ethylene glycol.

> Polyethylene is used to make Ziploc bags and folding tables. Identify which of these applications is most likely to be made from HDPE and which is most likely to be made from LDPE.

> Polyisobutylene cannot be described as isotactic, syndiotactic, or atactic. Explain.

> Should this polymer be classified as a chain-growth polymer or a step-growth polymer?

> Would these pairs of monomers form chain-growth or step-growth polymers? H,N- NH2 CN (a) ci CI (b)

> 88. Which of the following is the predominant form of proline at physiological pH (pH = 7.4)? 89. Which of the following terms properly describes this peptide? a. Tripeptide b. Tetrapeptide c. Pentapeptide d. Hexapeptide OH он N. H. (a) (b) N-H

> Nylon 6 is a polyamide used in the manufacture of ropes. It can be prepared via hydrolysis of ε-caprolactam to form ε-aminocaproic acid followed by acid-catalyzed polymerization. a. Draw the structure of Nylon 6. b. Compare th

> Identify the condensation polymer that would be produced when phosgene is treated with 1,4-butanediol.

> Identify the monomers required to make each of the following condensation polymers (a) (b)

> Kevlar is a condensation polymer used in the manufacture of bulletproof vests. Identify the monomers required for the preparation of Kevlar. H N- H N- Kevlar

> Draw the polymer that would be generated from the acidcatalyzed reaction between oxalic acid and resorcinol. HO. OH + HO OH Oxalic acid Resorcinol

> Draw the mechanism of formation of PET in acidic conditions. It might be helpful to first review the mechanism for the Fischer esterification process.

> A tube of superglue will harden if it remains open too long in a humid environment. Draw a mechanism that shows how superglue polymerizes in the presence of atmospheric moisture. When drawing your mechanism, make sure to draw the initiation step, at leas

> Many monomers that readily undergo cationic polymerization, such as isobutylene, will not readily undergo anionic polymerization. Styrene, however, can be effectively polymerized via cationic, anionic, or radical addition. Explain.

> Arrange the following monomers in order of reactivity toward anionic polymerization: NO2

> Arrange the following monomers in order of reactivity toward cationic polymerization: OAc NO2 CH3

> Draw a plausible mechanism for the following transformation: NO, NO, NAOH, H,O Heat

> Determine whether preparation of each of the following polymers would best be achieved via cationic addition or anionic addition: CN CN CN CN OMe OMe OMe OMe (a) (b) OAc (c) OAc OAc OAc NO2 NO2 NO2 NO2 Cla CCl, Cla ÇCla (d) (e) (f)

> Identify the monomers required to make the following alternating copolymer: ÇH3 H C-C-C-C- CH, H E-0-I エーQーエ I-0-I

> Draw a region of a block copolymer constructed from propylene and vinyl chloride.

> Draw a region of an alternating copolymer constructed from styrene and ethylene.

> Sodium polyacrylate is a synthetic polymer used in diapers, because of its ability to absorb several hundred times its own mass of water. This extraordinary polymer is made from another polymer, poly(methyl acrylate), via hydrolysis of the ester groups.

> Draw and name the polymer that results when each of the following monomers undergoes polymerization: OAc Br CH,CH, C=C H C=C C=C H H H H (a) Vinyl acetate (b) Vinyl bromide (c) a-Butylene

> Treatment of cholesterol with a peroxy acid (RCO3H) could potentially produce two diastereomeric epoxides. a. Draw both diastereomeric epoxides. b. Only one of these epoxides is formed. Predict which one and explain why the other is not formed.

> Sphingomyelins are lipids with the following general structure: a. Identify the polar head and all hydrophobic tails in sphingomyelins. b. Do sphingomyelins have the appropriate structural features and three-dimensional geometry necessary to be major c

> Circle the isoprene units in each of the following compounds: (a) Bisabolene (b) ) Flexibilene HO (c) Humulene (d) Vitamin A OH (e) Geraniol (f) Sabinene

> Draw a mechanism for the base-catalyzed transesterification of trimyristin using ethanol in the presence of sodium hydroxide.

> 87. What is the major product of this reaction? 88. Which compounds will react with each other in the presence of catalytic acid to give CH3CH2CO2C(CH3)3 via a Fischer esterification process? 89. Which of the following structures is not an intermediat

> Draw a mechanism for the transesterification of trimyristin using excess isopropanol in the presence of an acid catalyst.

> Draw the structures of trimyristin and tripalmitin and determine which is expected to have the lower melting point. Explain your choice.

> One of the compounds present in carnauba wax was isolated, purified, and then treated with aqueous sodium hydroxide to yield an alcohol with 30 carbon atoms and a carboxylate ion with 20 carbon atoms. Draw the likely structure of the compound.

> Identify which of the following statements applies to tristearin: a. It is a solid at room temperature. b. It is unreactive toward molecular hydrogen in the presence of Ni. c. It undergoes hydrolysis to produce unsaturated fatty acids. d. It is a com

> Which of the following statements applies to triolein? a. It is a solid at room temperature. b. It is unreactive toward molecular hydrogen in the presence of Ni. c. It undergoes hydrolysis to produce unsaturated fatty acids. d. It is a complex lipid.

> Which of the fatty acids in the previous problem has four carbon-carbon double bonds?

> Identify each of the following fatty acids as saturated or unsaturated: a. Palmitic acid b. Myristic acid c. Oleic acid d. Lauric acid e. Linoleic acid f. Arachidonic acid

> Identify whether hexane or water would be more appropriate for extracting terpenes from plant tissues. Explain your choice.

> Arrange the following compounds in order of increasing water solubility: a. A triglyceride constructed from one equivalent of glycerol and three equivalents of myristic acid b. A diglyceride constructed from one equivalent of glycerol and two equivalen

> Tristearin is less susceptible to becoming rancid than triolein. Explain.

> Identify what reagents you would use to make the following compound with a Robinson annulation reaction:

> Predict the major product for each of the following transformations: OH ? 1) Brg, PBr3 2) H,0 ? 1) Brz, PBr3 (а) 2) H,0 (b)

> Draw the structure of trans-oleic acid.

> Which of the following compounds are lipids? a. L-Threonine b. 1-Octanol c. Lycopene d. Trimyristin e. Palmitic acid f. d-Glucose g. Testosterone h. d-Mannose

> Draw a chiral triglyceride that contains one palmitic acid residue and two myristic acid residues. Will this compound react with molecular hydrogen in the presence of a catalyst?

> Draw two different cephalins that contain one lauric acid residue and one myristic acid residue. Are both of these compounds chiral?

> Predict the product(s) formed when tripalmitolein is treated with each of the following reagents: a. Excess H2, Ni b. Excess NaOH, H2O

> Identify each of the following compounds as a wax, triglyceride, phospholipid, steroid, prostaglandin, or terpene: a. Stanozolol b. Lycopene c. Tristearin d. Distearoyl lecithin e. PGF2 f. Pentadecyl octadecanoate

> Draw a mechanism for the biosynthesis of α-farnesene starting with dimethylallyl pyrophosphate and isopentenyl pyrophosphate. -Farnesene

> Draw a mechanism for the following transformation: ОPP OPP ОPP

> Determine whether each of the following compounds is a terpene: OH (a) OH (b) он OH (c) (d)

> Draw the product of the Robinson annulation reaction that occurs when the following compounds are treated with aqueous sodium hydroxide:

> Classify each prostaglandin according to the instructions provided in Section 26.7. но .COOH .COOH но (Ь) он он (a)

> The following compounds are steroids. One is an anabolic steroid called oxymetholone and the other, called norgestrel, is used in oral contraceptive formulations. Identify which compound is likely the contraceptive based on its structural features (funct

> Prednisolone acetate is an anti-inflammatory agent in clinical use. Itis similarin structure to cortisol, with the following two differences: 1. Prednisolone acetate exhibits a double bond between C1 and C2 of the A ring and 2. the primary hydroxyl gro

> Draw chair conformations for each of the following compounds and then identify whether each substituent is axial or equatorial: (a) (b) H H. HO (c)

> Draw the hypothetical ring-flip of trans-decalin and explain why it does not occur. Use this analysis to explain why cholesterol has a fairly rigid three-dimensional geometry.

> Would you expect glycerol to readily cross a cell membrane?

> Octanol is more efficient than hexanol at crossing a cell membrane and entering a cell. Explain.

> Draw the resonance structures of a fully deprotonated phosphatidic acid.

> A cephalin was hydrolyzed to yield one equivalent of palmitic acid and one equivalent of oleic acid. a. Draw two possible structures of the cephalin. b. If the phosphodiester was located at C2 of the glycerol unit, would the compound be chiral?

> A lecithin was hydrolyzed to yield two equivalents of myristic acid. a. Draw the structure of the lecithin. b. This compound is chiral, but only one enantiomer predominates in nature. Draw the enantiomer that is found in nature. c. The phosphodiester

> 85. What is the relationship between the following two carbohydrates? a. Enantiomers b. Diastereomers c. Resonance forms d. Constitutional isomers 86. Which of the following structures represents a pyranose form of glucose? CH,OH C=0 CHO H- -он

> The conversion of triglycerides into biodiesel can be achieved in the presence of either catalytic acid or catalytic base. We have seen a mechanism for transesterification with catalytic acid. In contrast, the mechanism for base-catalyzed transesterifica

> Draw the products obtained when triolein undergoes transesterification using isopropyl alcohol in the presence of catalytic sulfuric acid.

> Draw a mechanism for the transesterification of tristearin using methanol in the presence of catalytic acid.

> An achiral triglyceride was hydrolyzed to yield one equivalent of palmitic acid and two equivalents of lauric acid. Draw the structure of the triglyceride.

> A triglyceride was treated with sodium hydroxide to yield glycerol and three equivalents of sodium laurate (the conjugate base of lauric acid). Draw the structure of the triglyceride.

> Identify the products that are expected when the following triglyceride is hydrolyzed with aqueous sodium hydroxide:

> Partial hydrogenation of triolein produces several different trans fats. Draw all possible trans fats that might be obtained in the process.

> Triolein was treated with molecular hydrogen at high temperature in the presence of nickel. At completion, the reaction had consumed three equivalents of molecular hydrogen. a. Draw the structure of the product. b. Identify the name of the product. c.

> Identify each of the following compounds as a fat or an oil. Explain your answers. a. A triglyceride containing one palmitic acid residue and two stearic acid residues b. A triglyceride containing one oleic acid residue and two linoleic acid residues

> Tristearin has a melting point of 72°C. Based on this information, would you expect triarachadin to be classified as a fat or as an oil?

> The conjugate base of diethyl malonate can serve as a nucleophile to attack a wide range of electrophiles. Identify the product that is formed when the conjugate base of diethyl malonate reacts with each of the following electrophiles, followed by acid w

> Arrange the following three triglycerides in order of increasing melting point: Tristearin, tripalmitin, and tripalmitolein

> For each pair of triglycerides, identify the one that is expected to have the higher melting point. Consult Table 26.1 to determine which fatty acid residues are present in each triglyceride. a. Trilaurin and trimyristin b. Triarachidin and trilinolein

> Lanolin is a mixture of many compounds, one of which was isolated, purified, and then treated with aqueous sodium hydroxide to yield an unbranched alcohol with 20 carbon atoms and an unbranched carboxylic acid with 22 carbon atoms. Draw the structure of

> Waxes can be hydrolyzed to yield an alcohol and a carboxylic acid. Draw the products obtained when triacontyl hexadecanoate undergoes hydrolysis.

> Under similar conditions, alanine and valine were each prepared with an amidomalonate synthesis, and alanine was obtained in higher yields than valine. Explain the difference in yields.

> Show how you would use a Strecker synthesis to make valine.

> A mixture of amino acids was treated with ninhydrin, and the following aldehydes were all observed in the product mixture: a. Identify the structure and name all three amino acids in the starting mixture. b. In addition to the aldehydes, a purple-color

> Draw the products that are expected when each of the following amino acids is treated with ninhydrin: a. L-Aspartic acid b. L-Leucine c. L-Phenylalanine d. L-Proline

> A mixture containing glycine, L-glutamine, and L-asparagine was subjected to electrophoresis. Identify which of the amino acids moved the farthest distance assuming that the experiment was performed at the pH indicated: a. 6.0 b. 5.0

> Optically active amino acids undergo racemization at the α position when treated with strongly basic conditions. Provide a mechanism that supports this observation.

> Identify the Michael donor and Michael acceptor that could be used to prepare each of the following compounds via a Michael addition: OEt (a) (b) ČN OEt OEt -NO, CHO (c) OEt (d) (e) ON "NO2

> For each amino acid, draw the structure that predominates at the isoelectric point: a. L-Glutamine b. L-Phenylalanine c. L-Proline d. L-Threonine

> Just as each amino acid has a unique pI value, proteins also have an overall observable pI. For example, lysozyme (present in tears and saliva) has a pI of 11.0 while pepsin (used in our stomachs to digest other proteins) has a pI of 1.0. What informatio

> Using the data in Table 25.2, calculate the p of the following amino acids: a. L-Alanine b. L-Asparagine c. L-Histidine d. L-Glutamic acid From Table 25.2: TABLE 25.2 THE PK, VALUES FOR TWENTY NATURALLY OCCURRING AMINO ACIDS a-COOH a-NH3 * AMINO

> For each of the following amino acids, draw the form that is expected to predominate at physiological pH: a. L-Isoleucine b. L-Tryptophan c. L-Glutamine d. L-Glutamic acid

> Draw the form of L-glutamic acid that predominates at each pH: a. 1.9 b. 2.4 c. 5.8 d. 10.4

> Histidine possesses a basic side chain that is protonated at physiological pH. Identify which nitrogen atom in the side chain is protonated.

> Arginine is the most basic of the 20 naturally occurring amino acids. At physiological pH, the side chain of arginine is protonated. Identify which nitrogen atom in the side chain is protonated. (Hint: Consider all three possibilities and draw all reson

> Draw all stereoisomers of L-isoleucine. In each stereoisomer, assign the configuration (R or S) of all chiral centers

> Seventeen of the 20 naturally occurring amino acids exhibit exactly one chiral center. Of the remaining three amino acids, glycine has no chiral center, and the other two amino acids each have two chiral centers. a. Identify the amino acids with two chi

> Draw a Fischer projection for each of the following amino acids: a. L-Threonine b. L-Serine c. L-Phenylalanine d. L-Asparagine

> Nitriles undergo alkylation at the α position much like ketones undergo alkylation at the α position. The α position of the nitrile is first deprotonated to give a resonancestabilized anion (like an enolate), wh

> The 20 naturally occurring amino acids (Table 25.1) are all L amino acids, and they all have the S configuration, with the exception of glycine (which lacks a chiral center) and cysteine. Naturally occurring cysteine is an L amino acid, but it has the R

> Draw a bondline structure showing the zwitterionic form of each of the following amino acids: a. L-Valine b. L-Tryptophan c. L-Glutamine d. L-Proline

> Below is the primary structure for a peptide. Identify the regions that are most likely to form β pleated sheets. Trp-His-Pro-Ala-Gly-Gly-Ala-Val-His-Cys-Asp-Ser-Arg-Arg-Ala-Gly-Ala-Phe

> Identify the sequence of the tripeptide that would be formed from the following order of reagents. Clearly label the C terminus and N terminus of the tripeptide. 1) Boc ? Ph POLYMER 2) CF;COOH 3) Вос" OH, DCC 4) CF;COOH H 5) Boc ОН, DCC 6) CF,COOH 7)

> Identify all of the steps necessary to prepare each of the following peptides with a Merrifield synthesis: a. Phe-Leu-Val-Phe b. Ala-Val-Leu- le

> Draw all of the steps and reagents necessary to prepare a pentapeptide with the sequence Leu-Val-Phe- le-Ala.