5. When (R)-butan-2-ol is treated with TsCl in pyridine, the product formed is .
(A) a single enantiomer
(B) a racemic mixture
(C) a mixture of diastereomers
(D) an achiral compound
(E) none of the above

I. Choose one correct answer for the following questions 【單選題】每題 1 分，共計 60 分，答錯 1 題倒扣 0.25 分，倒扣至本大題零分為止，未作答，不給分亦不扣分。 1. What is the carbon nucleophile which attacks molecular bromine in the acid-catalyzed α-bromination of a ketone? (A) an enol (B) a Grignard reagent (C) an acetylide (D) a carbocation (E) an enolate

2. What species is attacked by the alcohol's hydroxyl in the mechanism of the Swern oxidation? (A) dimethylchlorosulfonium ion (B) dimethylsulfoxide (C) oxalyl chloride (D) oxalinium ion (E) aldehyde or ketone

3. When pyridine is treated with a mixture of nitric and sulfuric acids, the major product is . (A) 2-nitropyridine (B) 3-nitropyridine (C) 4-nitropyridine (D) 3-aminopyridine (E) 4-aminopyridine

4. What is the major organic product of the following reaction?

6. What kind of polymer is produced in the following reaction? (A) a polycarbonate (B) poly(acrylonitrile) (C) a polyester (D) polyurethane (E) a synthetic rubber

7. Which of the following reagents should be used to convert hex-3-yne to {E}-hex-3-ene? (A) H2, Pt (B) Na, NH3 (C) H2, Lindlar's catalyst (D) H2SO4, H2O (E) HgSO4, H2O

8. SN1 reaction usually proceed with . (A) slightly more inversion than retention at the center undergoing substitution (B) slightly more retention then inversion at the center undergoing substitution (C) equal amounts of inversion and retention at the center undergoing substitution (D) complete inversion at the center undergoing substitution (E) complete retention at the center undergoing substitution

9. Peptide bonds are . (A) ester linkages (B) imido linkages (C) amide linkages (D) ether linkages (E) disulfide linkages

10. What is the major product of the following reaction?

11. What compound is produced when (CH3)2CHCH2Br is subjected to the following sequence of steps: 1. Mg, Et2O, 2. CO2, 3. H3O+ ? (A) 2-methylpropanoic acid (B) 3-methylpropanoic acid (C) 2-methylbutanoic acid (D) 3-methylbutanoic acid (E) 2-methylhexanoic acid