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Removal of water from alcohols

Alcohols that are branched at the -position to the hydroxyl group, such as 3,3-dimethyl-2-butanol, rearrange readily on dehydration4,5 (the retropinacol rearrangement6)  [Pg.814]

The carbon chain is cleaved when, e.g., 2,2,4,4-tetramethyl-3-pentanol is heated with chloronaphthalenesulfonic acid at 180° 7 [Pg.814]

The direction in which water is removed generally follows SaytzefFs rule, according to which the hydrogen atom is removed from the /3-carbon atom carrying the smallest number of hydrogen atoms or largest number of alkyl groups.8 [Pg.814]

This leads to the olefin with the largest number of alkyl groups on doubly bonded carbon. For instance, 3-methyl-2-butanol in concentrated sulfuric acid affords 2-methyl-2-butene and not 3-methyl-1-butene  [Pg.814]

As mentioned elsewhere (page 280), addition of water to an olefin occurs so that hydrogen is added to the carbon atom already carrying the larger number of hydrogen atoms readdition of water to 2-methyl-2-butene thus affords 2-methyl-2-butanol, (CH3)2C(OH)CH2CH3, and not 3-methyl-2-butanol. [Pg.814]


Symmetrical aliphatic ethers (C -Ci,) are prepared by the removal of water from alcohols under acidic conditions. Thus, in the preparation of diisoamyl ether, the alcohol is heated with concentrated sulfuric acid or p-toluenesulfonyl chloride in a flask equipp>ed with a condenser and a water sep>arator. The top layer of alcohol and ether is returned to the reaction flask until water no longer separates. Any alcohol remaining in the ether is converted to the higher-boiling triisoamyl borate, and the ether is purified by fractional distillation. Several suitable water separators have been described. High reaction temperatures must be avoided to prevent the formation of unsaturated hydrocarbons (cf. method 19). [Pg.120]


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