Unformatted text preview: Nomenclature NM-G. What is the IUPAC name for this compound? (A) methyl butanoate
(C) propyl methanoate Knowledge Required: Procedure for naming esters. Thinking it Through.- Bsters are derivatives of carbonylic acids and alcohols. To name an ester, identify the
alkyl group that is in the “alcohol" portion of the molecule and name it, then idenﬁfy and name the “acid” part :
the molecule.Theesterisnamedwiththealkylpartﬁrshandtheacidpmtisnamedasacarboxylate. For example.
R-C-OH + H-O-R‘ -—- R—C—O—R' +H20 .
pan" PM" In the probln . the alcohol portion is derived from 1-propanol. Tha'efore, the alkyl group is a wopyl group. The carboxyﬁc acid portion of the molecule is derived from ethanoic acid. Thus the answer is propyl ethanoate.
which is (D). A helpful hint: Use "carbon atom counts" to eliminate choices which do not correspond to that of the given
strucutre. For example. the ester CH3CHQCH2COOCHQCH3 contains a total of six carbon atoms. Therefore any
beeliminated. lfthename“propyl edranoate“ wereapossible answer. itcouldherejected immediately hecausethe
propyl yormoontainsﬂireecarbonatomsandethanoatecontaim twocarhonatoms.foratota.lofﬁve.Similarly,
ifthequestionaskedwhichoffmusnucnu'escorrespond withagiven name.itshouldhepossibletocountupthc
number of carbon atoms suggested in the name and reject any possible structures that differ from this number. This
approach will often narrow the choices, but it is usually necessary to examine the alkyl and acid portions of the
ester closely to be absolutely sure. Using this “carbon atoms counts” approach. choice (B) can be rejected because methyl wopanoate is derived from
methanol (1 carbonatom) andpropanoic acid (3 carbon atoms). The molecule shown inthequestion has ﬁve
carbon atoms, so choice (B) can be eliminated from consideration. Similarly, choice (C) is eliminated because the
choices havethecorrect number ofcarbonatoms. then look atthe sn'ucnnesofthealeohol's alkyl groupandatthe
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- Spring '10
- Organic chemistry