27. Which of the following is the rate-determining step for the monobromination of cyclohexane?

 
(A) Step I
(B) Step II
(C) Step III
(D) Step IV
(E) Step V

23. Which of the following descriptions of the nucleoside uridine does not apply to the structure of the molecule? (A) The uracil base is directly bonded to the 1' position of ribofuranose in the α position. (B) The ribofuranose moiety is found in only the D configuration. (C) Nitrogen, at position 1 in the uracil base, is directly bonded to the ribofuranose moiety. (D) The 5' OH group is replaced with phosphate(s) in the nucleotide structure. (E) none of the above

24. Which of the following is correct in order of decreasing nucleophilicity toward methyl iodide in methanol? (A) CH3O- > CH3S- > CN- > Br- (B) CH3O- > CN- > CH3S- > Br- (C) CN- > CH3O- > CH3S- > Br- (D) CH3S- > Br- > CH3O- > CN- (E) CH3S- > CN- > CH3O- > Br-

25. Which of the following compounds will undergo SN2 reaction most readily? (A) (CH3)3CCH2I (B) (CH3)3CCl (C) (CH3)2CHI (D) (CH3)2CHCH2CH2CH2I (E) (CH3)2CHCH2CH2CH2Cl

26. Which of the following carbonyl compounds can be reduced by H2/Raney Ni? (A) acetic acid (B) ethyl acetate (C) acetyl chloride (D) acetamide (E) N-methyl acetamide

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

29. Which are ylides?  (A) only I (B) only II (C) I and II (D) II and III (E) III and IV

30. Which of the following chemical reactions could be used to distinguish between a polyunsaturated vegetable oil and a petroleum oil containing a mixture of saturated and unsaturated hydrocarbons? (A) addition of bromine in carbon tetrachloride (B) ozonolysis (C) hydrogenation (D) lipidification (E) saponification

31. When an alkene is subjected to treatment with Hg(OAc)2 in alcohol followed by reaction with NaBH4, what new class of compound is formed? (A) ether (B) epoxide (C) alkane (D) syn diol (E) alkyne

32. Distillation of mixtures of ethanol and water cannot increase the ethanol content of the mixture above 95% because this solution boils at a lower temperature than either pure ethanol or pure water. The term which describes this lower boiling mixture is _____. (A) miscible (B) azeotrope (C) isoniazide (D) epimerization (E) none of these

33. The methyl ester of a carboxylic acid can be synthesized by directly using . (A) SOCl2 (B) PCl5 (C) CH2N2 (D) C2O2Cl2 (E) CH3NH2