H(CH; CH CH3 tertbutyl C(CH3 ) When these descriptors are used in an IUPAC name, iso is alphabetized normally the hyphenated prefixes, however (sec- and tert-)are disregarded when alphabetizing A more systematic method for the nomenclature of side-chains involves identifying the longest chain in the substituent, numbering the substituent from the point of attachment to the parent, and indicating side-chains on the substituent using the standard me thod described for simple alkanes. The name is enclosed in parenthesis to indicate that the numbering corresponds to the local side-chain, not the parent chain. Thus: an isopropyl side-chain can also be named(1-methylethyl), a sec-butyl side-chain can also be named(I-methylpropy l), an isopentyl side-cha in can also be named (3-methy butyl), etc CH-CH -CH-CHa-CH H CH -methy lpropy D) or-(1, 1-dimethy lathy D) CH2-CH2-CH-CH. H2-CH-CH2-CH As a student of organic chemistry, you will encounter a variety of nomenclature conventions, and many non-standard names in common usage must simply be learned. Systematic nomenclature, however, is important to clearly understand as these hods are utilized in the cataloging of chemical inf int and computerized databases and effective information retrieval requires a good working knowledge of these methods The origin of the prefixes sec-and tert-, given above, rests with an attempt to describe the nature of the branched carbon unit. By definition, a primary carbon is one which is attached to one other carbon atom, a secondary carbon is one which is attached to two, a tertiary carbon is attached to three, and quaternary carbon is attached to four other carbon atoms; these are often abbreviated as 1, 2, 3 and 4. carbonssec-butyl -CH(CH3)CH2CH3 tert-butyl -C(CH3)3 When these descriptors are used in an IUPAC name, iso is alphabetized normally; the hyphenated prefixes, however (sec- and tert-) are disregarded when alphabetizing. A more systematic method for the nomenclature of side-chains involves identifying the longest chain in the substituent, numbering the substituent from the point of attachment to the parent, and indicating side-chains on the substituent using the standard method described for simple alkanes. The name is enclosed in parenthesis to indicate that the numbering corresponds to the local side-chain, not the parent chain. Thus: • an isopropyl side-chain can also be named (1-methylethyl), • a sec-butyl side-chain can also be named (1-methylpropyl), • an isopentyl side-chain can also be named (3-methylbutyl), etc. As a student of organic chemistry, you will encounter a variety of nomenclature conventions, and many non-standard names in common usage must simply be learned. Systematic nomenclature, however, is important to clearly understand as these methods are utilized in the cataloging of chemical information in print and computerized databases and effective information retrieval requires a good working knowledge of these methods. The origin of the prefixes sec- and tert-, given above, rests with an attempt to describe the nature of the branched carbon unit. By definition, a primary carbon is one which is attached to one other carbon atom, a secondary carbon is one which is attached to two, a tertiary carbon is attached to three, and a quaternary carbon is attached to four other carbon atoms; these are often abbreviated as 1o, 2o, 3o and 4o carbons