CEMISTY 314-01 MIDTEM # 4 ASWE KEY April 16, 00 1. (6 pts) Mark as true (T) or false (F) the following statements. Do not explain! (F) Amides are less reactive than acid chlorides but more reactive than esters; (F) Saponification is the process of base-catalyzed formation of esters; (T) The ofmann elimination results in the predominant formation of the least substituted alkene; (F) The Cope elimination results in the predominant formation of the most substituted alkene; (F) The ofmann rearrangement is the rate-determining step of the ofmann elimination; (T) Lactones are cyclic esters;. Circle all that apply: A. (3 pts) The Sandmeyer reaction is used to prepare: a. Aryl bromides ; b. Aryl iodides; c. Aryl cyanides ; d. Azo dyes; B. (3 pts) Circle the methods that can be used LY for the preparation of primary amines: a. Gabriel synthesis ; b. eduction of nitriles ; c. eduction of azides ; d. ofmann rearrangement; C. (3 pts) The Fischer esterification is: a. Catalyzed by acids only ; b. Catalyzed by bases only; c. Catalyzed by both acids or bases d. Irreversible; D. (3 pts) Circle the reagents that CAT be used to convert a carboxylic acid to an acid chloride: a. Thionyl Chloride; b. Phosphorus Pentachloride; c. xalyl Chloride; d. Sodium Chloride; E. (3 pts) Circle the reagents that can reduce a carboxylic acid to an alcohol: a. aney-ickel; b. Sodium Borohydride; c. Lithium Aluminum ydride; d. B 3.TF; 3. (4 pts) ame the following compounds: 3 C 3,3-dimethylpentanedioic anhydride methyl phenylethanoate methyl phenylacetate phenylmethyl ethanoate benzyl acetate 6-amino-4-hexenoic acid lactam 4. (4 pts) Provide structures for the following compounds: C Br cis-1,-cyclopropanedicarboxylic anhydride -methylhexanenitrile 3-chlorobutanoyl bromide -methyl-γ-butyrolactam
5. (4 pts) ank the following compounds in order of increasing acidity: A. Trifluoroacetic acid; B. Phenol; C. Butanoic acid; D. -chloropropanoic acid; E. t-butanol; F. Sodium ydride; F < E < B < C < D < A 6. (4 pts) Although nitrogen centers are generally more basic than oxygen centers, protonation of amides in acid occurs at oxygen rather than nitrogen. Suggest a reason for this, taking resonance into account. 3 3 3 no possibility for resonance stabilization protonation at nitrogen protonation at oxygen resonance stabilization of poisitive charge 7. (6 pts) Suggest a plausible mechanism for the following reaction. 1. BrMg. 3 BrMg 3 8. Write a complete equation for each of the processes indicated below (TE: Do not write mechanisms!!). A. (3 pts) eaction of maleic anhydride (cis-butenedioic acid anhydride) with ethanol. C 5 C 5 B. (3 pts) eaction of acetic formic anhydride with t-butylbenzene, in the presence of Al 3. Al 3 C C. (3 pts) Saponification of γ-butyrolactone. a - a
D. (3 pts) eaction of,3-dimethylhexanoic acid with diazomethane. C C 3 E. (3 pts) eaction of benzoic acid with B 3.TF complex. C C B 3.TF F. (3 pts) eduction of phenylacetylchloride with LiAl(Bu-t) 3. LiAl(Bu-t) 3 9. (9 pts) Fill in the blanks in the following reaction scheme: 1. Mg/ether. C Br 3. 3 S C C 3 C Br, a 1. excess C 3 I. Ag, water 1. acetone. LiAl 4 3. acetone, ab MCPBA
10. (1 pts) Draw the products of the following reactions: KMn 4 water/ t-butanol C C C P 5 3 Br, -, pyridine a, - 1. LiAl 4. Cu S 4 a, KI 3 P I 11. Suggest a plausible synthetic sequence for the preparation of the following compounds: A. (6 pts) The preparation of heptanedioic acid (pimelic acid) from pentanedioic acid (glutaric acid). B 3.TF or 1. LiAl 4. 3 PBr 3 Br Br ac 3 C C B. (6 pts) The preparation of the insect-repellant,-diethyl-m-toluamide (DEET), starting from m-bromotoluene.? Br 1. Mg/ether. C 3. 3 (C 5 ) pyr P 5
1. (6 pts) Propose structures for the following compounds, based on their 1 M data. C 8 14 4 3 C 5 C 5 5.0 4.5 4.0 3.5 3.0.5.0 1.5 1.0 0.5 C 8 11 3 8.0 7.5 7.0 6.5 6.0 5.5 5.0 4.5 4.0 3.5 3.0.5.0 1.5 1.0 0.5
13. BUS PBLEMS. A. (5 pts) You are familiar with the ofmann earrangement and its mechanism. It turns out that other reactions follow a similar mechanism. An example is shown below of the so-called Lossen earrangement. Write the detailed mechanism of the process. C C ' - C C C C ' concerted rearrangement C C C C ' B. (5 pts) The reaction of benzil with concentrated a solution gives the sodium salt of benzilic acid. Write the mechanism for this process. a a a a proton transfer