| 摘要 |
<p>Pinacols are prepared by reducing a ketone, e.g p-hydroxypropiophenone with an alloy of lead and an alkali metal, e.g. sodium, potassium or lithium in a solvent capable of forming nascent hydrogen under the reaction conditions, such as alcohol, mixtures of glacial acetic acid and alcohol, aqueous alcohol or water. In a preferred modification alkaline earth metal ions, i.e. ions of magnesium, calcium, barium and strontium, are added to the reaction mixture either by adding an ion producing salt or other compound to the reaction mixture, or by incorporating an alkaline earth metal in the alkali metal-lead alloy. The alkali metal-lead alloy may contain from 5-40 per cent of alkali metal, preferably from 8-15 per cent. Ketones which may be reduced include dialkyl, alkyl aryl, diaryl and alkyl aralkyl ketones and substitution derivatives thereof in which the substituent group is non-reactive under the conditions of the reaction. Water-insoluble ketones containing a group such as hydroxy, carboxyl or sulfo capable of forming a water-soluble salt may be converted to the salt and the reduction is then carried out in water. In examples, there are obtained by reduction of the appropriate ketone with a sodium lead alloy, 3 : 4 - bis - (p - hydroxyphenyl) - 3 : 4 - hexanediol, 4 : 5 - bis - (p - methoxyphenyl) - 4 : 5 - octanediol, 3 : 4 - bis - (p - chlorophenyl) - 3 : 4 - hexanediol and 3 : 4-diphenyl-3 : 4-hexanediol, and by reduction of p-hydroxypropiophenone with a sodium lead alloy in alcoholic acetic acid followed by acetylation there is obtained 3 : 4-bis-(p-acetoxyphenyl)-3 : 4-hexane diol.</p> |
