| 摘要 |
1,167,093. 4,4<SP>1 </SP>- Dihydroxy - stilbenes. WACKER-CHEMIE G.m.b.H. 16 Aug., 1967 [17 Aug., 1966], No. 37723/67. Heading C2C. A process for preparing 4,4<SP>1</SP>-dihydroxystilbenes of the general formula in which R 1 , R 2 , R 3 and R 4 , which may be the same or different, each represent a hydrogen or halogen atom or an alkyl or aryl group, comprises condensing a phenol of general formula with a monohalogenoacetaldehyde in the presence of glacial acetic acid and concentrated sulphuric acid at a temperature within the range of - 20‹ to + 25‹ C., dehydrohalogenating the condensation product utilizing an alcoholic alkali metal hydroxide solution and intramolecularly re-arranging the dehydrohalogenation product at a temperature within the range of 150‹ to 220‹ C. The monohalogenated acetaldehyde may be prepared in situ from an acetal thereof.
|
