Unformatted text preview: Nomenclature NM-‘l’. What is the IUPAC name for this compound? CH3 0
CH3-CH=CH- CH—C-OH (A) 4-methyl-2-pentenoic acid (B) 2-methyl-3-pentenoic acid
(C) 5—hyth‘oxy-4-mcthyl-2-penten-S-one (D) l-hydroxy-Z—methyl-B-penten—l—one Imn—umoo-mInIMI.-ImemalleonﬂuI“.In”mam-“menace..-n-I—lnommu..-u-nnan““In."u-quInOIw-nlmueumuu ..u..-unuumm nu“ IM—ltlulln-Ilu Knowledge Required: (1) Recognition of functional groups. (2) Procedure for naming carboxylic acids.
(3) Procedure for naming alkenes. (4) Setting priorities of functional groups when assigning numbers. Thinking it Through: When solving nomenclamre problems, immediawa reject any choice containing a
nonexistent functional group. For example. if a molecule contains the CONE-I, group, one of the choices may
contain the phrases such as “amino ketone" or “ketoamine.” Note that these two terms are not true functional
groups. Correct terms for this group are “arni " or “carboxamide.” Similarly. take care not to mistake one real
functional group for another. such as amide for amine or vice versa. The procedure for determining the proper name for this compound is similar to the previous problems. The
two functional groups present are a carboxyh'c acid and an alkene. ﬁrst number the main chain containing the
carbonylic acid. This chain has ﬁve carbon atoms. so the name will be derived from pentanoic acid. Choices (C)
and (D) can be eliminated because they call the carboxylic acid group a hydroxyketone—-a nonexistent functional
group. (Note that there are ketones containing hydroxyi groups, but they never have the hydroxyl group attached to
the carbonyl carbon atom. A hydroxyl attached to a carbonyl group is a carbonylic acid, period.) Next, the chain has to be numbered. Carbonylic acid groups have absolute priority in numbering, so the carboxylic
acid carbon atom is always C—l. Therefore, the methyl group is on C—2. and the double bond is between 0—3 and
0-4. Choice (A) can be eliminated because the chain is numbered from the end Opposite the carboxylic acid.
Choice (3) is the correct answer. NM-S. Which is the structure of N-benzylethanamide? (A) 9
CH3‘CHz'NH Knowledge Required: (1) Procedure for naming amides. (2) Distinction between the phenyl and benzyl groups. Thhtkiug it Through: Consider the name of the compound: N-benzylethanamide. This name saysjt is based
on ethsnamide (the primary amide daived from ethanoic acid) so it is based on the general structure CH;CONH¢.
The name also says that theme is a benzyl group attached to the nitrogen atom. The benzyl group is CﬁrCH,—.
Therefore the correct answer is choice (A). Choice (C) can be eliminated because it does not contain an amide
group. This compound is N—cthylsniiinc. Choice (B) is also incorrect because there is no amide group present.
This compound is benzyiethylsmine. Choice (1)) contains an amide group and is indeed derived from ethanamide.
However, nosethatthegrottpahachedtodtenihogenatomisaphenylgroupmotahenzyi group. Itisailtoo
easy to confuse the phenyl and benzyl groups. so caremust be taken when looking at names or struchu'es. ...
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- Spring '10
- Organic chemistry