74 ALCOHOLS AND ALKYL HALIDES (b) This compound has the same carbon skeleton as the compound in part (a) but bears a hydroxyl group in place of the bromine and so is named as a derivative of l-pentanol CH CHCH,CHCH,OH (c) This molecule is a derivative of ethane and bears three chlorines and one bromine The name 2-bromo-l, 1, I-trichloroethane gives a lower number at the first point of difference than 1-bromo-2. 2.2-trichloroethane. ClCCH, Br 2-Bromo.1.1.1-trichloroethane (d) This compound is a constitutional isomer of the preceding one. Regardless of which carbon the numbering begins at, the substitution pattern is 1, 1, 2, 2. Alphabetical ranking of the halo- gens therefore dictates the direction of numbering. Begin with the carbon that bears bromine ClCHCHBr I-Bromo-1. 2.2-trichloroethane (e) This is a trifluoro derivative of ethanol. The direction of numbering is dictated by the hydroxyl group, which is at C-l in ethanol CF, CHOH 2.2.2-Trifluoroethanol (f) Here the compound is named as a derivative of cyclohexanol, and so numbering begins at the carbon that bears the hydroxyl group cis-3-tert-Butylcyclohexanol (g) This alcohol has its hydroxyl group attached to C-2 of a three-carbon continuous chain; it is named as a derivative of 2-propanol - OH 2-Cyclopentyl-2-propanol (h) The six carbons that form the longest continuous chain have substituents at C-2, C-3, and c-5 when numbering proceeds in the direction that gives the lowest locants to substituents at the first point of difference. The substituents are cited in alphabetical order 5-Bromo-2.3-dimethylhexane Had numbering begun in the opposite direction, the locants would be 2, 4, 5 rather than 2,3,5 Back Forward Main Menu TOC Study Guide Toc Student OLC MHHE Website(b) This compound has the same carbon skeleton as the compound in part (a) but bears a hydroxyl group in place of the bromine and so is named as a derivative of 1-pentanol. (c) This molecule is a derivative of ethane and bears three chlorines and one bromine. The name 2-bromo-1,1,1-trichloroethane gives a lower number at the first point of difference than 1-bromo-2,2,2-trichloroethane. (d) This compound is a constitutional isomer of the preceding one. Regardless of which carbon the numbering begins at, the substitution pattern is 1,1,2,2. Alphabetical ranking of the halo￾gens therefore dictates the direction of numbering. Begin with the carbon that bears bromine. (e) This is a trifluoro derivative of ethanol. The direction of numbering is dictated by the hydroxyl group, which is at C-1 in ethanol. ( f ) Here the compound is named as a derivative of cyclohexanol, and so numbering begins at the carbon that bears the hydroxyl group. (g) This alcohol has its hydroxyl group attached to C-2 of a three-carbon continuous chain; it is named as a derivative of 2-propanol. (h) The six carbons that form the longest continuous chain have substituents at C-2, C-3, and C-5 when numbering proceeds in the direction that gives the lowest locants to substituents at the first point of difference. The substituents are cited in alphabetical order. Had numbering begun in the opposite direction, the locants would be 2,4,5 rather than 2,3,5. 1 2 3 4 5 6 Br 5-Bromo-2,3-dimethylhexane CH3 CH3 OH 2-Cyclopentyl-2-propanol cis-3-tert-Butylcyclohexanol OH 2,2,2-Trifluoroethanol CF3CH2OH 1-Bromo-1,2,2-trichloroethane Cl2CHCHBr Cl Cl3CCH2Br 2-Bromo-1,1,1-trichloroethane CH3 CH3CHCH2CH2CH2OH 4-Methyl-1-pentanol 74 ALCOHOLS AND ALKYL HALIDES Back Forward Main Menu TOC Study Guide TOC Student OLC MHHE Website