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Abstract |
AB |
[EN] Tertiary acetylenic alcohols are produced by reacting acetylene with a ketone under substantially anhydrous conditions and in the presence of an alkali metal alkoxyethoxide of formula ROCH2CH2OM in solution in an alkoxyethanol of formula ROCH2CH2OH, where R in each case represents an alkyl group of one to six carbon atoms, to form the alkali metal derivative of a tertiary acetylenic alcohol, and recovering the alcohol from its alkali metal derivative. Preferably the alkali metal alkoxyethoxide is in solution in the corresponding alkoxyethanol, in which case the solution may be prepared by adding aqueous alkali metal hydroxide to an excess of alkoxyethanol at a subatmospheric pressure, maintaining the mixture at boiling point, and removing water by distillation with a hydrocarbon entraining agent, such as benzene or toluene. A preferred condensing agent is potassium n-butoxyethoxide in n-butoxyethanol. Suitable ketones for carrying out the process are acetone, methyl ethyl ketone, methyl propyl ketone, diethyl ketone, methyl amyl ketone, di-isopropyl ketone, cyclohexanone, and methylheptenone. The molar ratio of ketone to alkoxyethoxide is suitably from 0.30: 1 to 0.95: 1, preferably about 0.75: 1. The condensation may be carried out at below 60 DEG C., preferably 0-30 DEG C. The pressure may be atmospheric or superatmospheric. The tertiary acetylenic alcohol may be liberated from its alkali metal derivative by (i) adding water, extracting with a solvent at a comparatively low temperature, and recovering the free alcohol from the solvent; (ii) hydrolysis, treating with CO2, removing alkali metal carbonate, and solvent extraction; (iii) adding water, removing or neutralizing alkali metal hydroxide, and distilling; (iv) washing the crude product with water, converting the alkali metal derivative to free alcohol, neutralizing alkali metal hydroxide and distilling; (v) (where acetone or methyl ethyl ketone is used) distilling the crude reaction product, after adding water, at not above 60 DEG C. under reduced pressure, e.g. 100-150 mm., to obtain the free alcohol. In Examples (1) and (2) acetone is reacted with acetylene to produce 2-methyl-but-3-yn-2-ol; (3), (4), (5) and (8) methyl ethyl ketone produces 3-methyl-pent-1-yn-3-ol; (6) and (7) 6-methylhept-5-ene-2-one produces dehydrolinalol (all using potassium n-butoxyethoxide in n-butoxyethanol); and methyl ethyl ketone produces 3-methyl-pent-1-yn-3-ol, using (a) potassium n-propoxyethoxide in n-propoxyethanol; and (10) sodium n-butoxyethoxide in n-butoxyethanol. |
