a polar O–H bond, have intermediate boiling points due to the presence of a small dipole moment (Table below). The larger the alkyl group in the molecule, however, the more the “alkane-like” alcohol is in its properties. Because of their polar nature, alcohols and ethers tend to be good solvents for a wide range of organic compounds. Molecular Boiling Name Formula Mass (amu) (°C) propane C3H8 44 −42.1 alkane n-pentane C5H12 72 36.1 n-heptane C7H16 100 98.4 dimethylether (CH3)2O 46 −24.8 ether diethylether (CH3CH2)2O 74 34.5 di-n-propylether (CH3CH2CH2)2O 102 90.1 ethanol CH3CH2OH 46 78.3 alcohol n-butanol CH3(CH2)3OH 74 117.7 n-hexanol CH3(CH2)5OH 102 157.6 Boiling Points of Alkanes, Ethers, and Alcohols of Comparable Molecular Mass Alcohols are usually prepared by adding water across a carbon–carbon double bond or by a nucleophilic substitution reaction of an alkyl halide using hydroxide, a potent nucleophile. As you will see, alcohols can also be prepared by reducing compounds that contain the carbonyl functional group (C=O; part (a) in the third to last Figure above). Alcohols are classified as primary, secondary, or tertiary, depending on whether the group is bonded to a primary, secondary, or tertiary –OH carbon. For example, the compound 5-methyl-3-hexanol is a secondary alcohol.
a polar O–H bond, have intermediate boiling points due to the presence of a small dipole moment (Table below). The larger the alkyl group in the molecule, however, the more “alkane-like” the alcohol is in its properties. Because of their polar nature, alcohols and ethers tend to be good solvents for a wide range of organic compounds. Name Formula Molecular Mass (amu) Boiling (°C) alkane propane C3H8 44 −42.1 n-pentane C5H12 72 36.1 n-heptane C7H16 100 98.4 ether dimethylether (CH3)2O 46 −24.8 diethylether (CH3CH2)2O 74 34.5 di-n-propylether (CH3CH2CH2)2O 102 90.1 alcohol ethanol CH3CH2OH 46 78.3 n-butanol CH3(CH2)3OH 74 117.7 n-hexanol CH3(CH2)5OH 102 157.6 Boiling Points of Alkanes, Ethers, and Alcohols of Comparable Molecular Mass Alcohols are usually prepared by adding water across a carbon–carbon double bond or by a nucleophilic substitution reaction of an alkyl halide using hydroxide, a potent nucleophile. As you will see, alcohols can also be prepared by reducing compounds that contain the carbonyl functional group (C=O; part (a) in the third to last Figure above). Alcohols are classified as primary, secondary, or tertiary, depending on whether the –OH group is bonded to a primary, secondary, or tertiary carbon. For example, the compound 5-methyl-3-hexanol is a secondary alcohol.
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