Sodamide dehydrohalogenation

Nearly all methods for preparation of stearolic acid involve de-hydrohalogenation of a 9,10-dihalostearic acid, or its esters, with alcoholic potassium hydroxide the most recent method is that of Adkins and Burks.8 These methods employ drastic conditions, which result in poorer yields than those obtainable on dehydrohalogenation with sodamide.6 Methyl 9,10-dibromostearate, on dehydrobromi-nation with sodamide, yields stearolamide 6 (m.p. 82-83°) which may be hydrolyzed to stearolic acid. For preparative purposes, however, this method offers-no special advantage over that described here. 

Most of the compounds formed are new and were formerly inaccessible,7 being only available by dehydrohalogenation of gem-inal or 1,2-dibromides which are often unavailable themselves.7 Alcoholic potassium hydroxide8,9 or sodamide in liquid paraffin7,10 under forceful conditions has been used for this elimination, but yields are generally not good.7"10... 

Phenylacetylene is readily prepared by the dehydrohalogenation of styrene dibromide with a solution of sodamide in liquid ammonia ... 

The amide ions are powerful bases and may be used (i) to dehydrohalogenate halo-compounds to alkenes and alkynes, and (ii) to generate reactive anions from terminal acetylenes, and compounds having reactive a-hydrogens (e.g. carbonyl compounds, nitriles, 2-alkylpyridines, etc.) these anions may then be used in a variety of synthetic procedures, e.g. alkylations, reactions with carbonyl components, etc. A further use of the metal amides in liquid ammonia is the formation of other important bases such as sodium triphenylmethide (from sodamide and triphenylmethane). 

The most important dehydrohalogenating agents for introducing triple bonds are potassium hydroxide and sodamide, but other basic reagents may also be used, e.g.r alkali alkoxides, hydrides, and carbonates, alkaline-earth hydroxides and carbonates, and occasionally organometallic compounds. 

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