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250  Answers
310. (C) This is an OH stretch. The only compound choice with an OH group is the alcohol.
311. (D) The IR indicates the presence of a carbonyl group; the NMR and Tollens’ test 
eliminate an aldehyde, leaving only a methyl ketone to generate the iodoform.
312. (B) Sodium hydroxide would convert the boric acid to water-soluble borate ion, 
which ends in the aqueous layer. The organic compounds would probably be in the ether 
layer. Since the reaction was incomplete, some of the original ester would remain along with 
the alcohol formed.
313. (A) The compound is symmetric, so it is necessary to consider only one side. Starting 
from the left and counting to (and including) the carbonyl carbon, there are four different 
carbon atoms.
314. (D) There are five different chemical environments for the carbon atoms: the methyl 
carbons, the ring carbon between the methyl substituents, the carbons the methyl groups 
are attached to, the carbons that are ortho to the methyl substituents, and the carbon that 
is meta to the methyl groups.
315. (D) Aqueous sodium bicarbonate will extract the carboxylic acids (all the com-
pounds). In any case, all the chemical species can hydrogen-bond to water and therefore 
will be soluble in the aqueous layer.
316. (A) Sodium bicarbonate will extract acids like the carboxylic acid (II); however, phe-
nols are too weak to react. Compounds II and IV can hydrogen-bond strongly to water, and 
thus they would be in the aqueous layer.
317. (C) The reaction produces carbonyls (1700 cm–1), not alcohols (3300 cm–1 and 
1300 cm–1) or ethers (1250 cm–1).
318. (A) In general, unsaturated fatty acids have lower melting points than saturated fatty 
acids. The cis isomers tend to have lower melting points than the corresponding trans iso-
mers. The lowest-melting isomer will be the one with the greatest number of cis bonds (Z): 
(9Z, 12Z, 15Z)-9,12,15-octadecatrienoic acid
319. (C) Extraction, chromatography, and distillation are all separation techniques, while 
IR spectroscopy is a technique used to determine the structure of a compound.
320. (B) NMR spectroscopy is not a separation technique; thin-layer chromatography 
can be used for identification, but not for an actual separation (especially if large quantities 
are present); and extraction would involve finding a solvent that one of the compounds is 
insoluble in and then removing the solvent at the end. There should be a significant differ-
ence in the boiling points of these two compounds, since the alcohol can hydrogen-bond 
to other alcohol molecules and the other compound cannot. Therefore, distillation should 
be the simplest method for separating a mixture of the two.