Reactions of alpha-halogenoketones with aromatic compounds – Part I: Reactions of chloroacetone and 3-chlorobutanone with phenol and its ethers.

S H ZAHEER, P M BHARGAVA, B SINGH, B BHUSHAN, I K KACHKER, K RAMCHANDRAN, V D N SASTGRI & N S RAO

Published in: Journal of the Chemical Society, 1954, 3360-3362

Abstract:

Condensation of α-halogenoketones, R .CHCI.COR ‘ (R = H or Me; R’ = Me), with phenol or its ethers in the presence of concentrated sulphuric acid or aluminium chloride yielded substituted stilbene derivatives.

Condensation of chloroacetone with phenol and its ethers in presence of concentrated sulphuric acid and anhydrous aluminium chloride as catalysts has been studied with a view to prepare compounds, CH2Cl.CMeAr2 , which might have insecticidal properties like those of DDT. Lippmann has reported (Ber., 1912, 45, 2490) that chloroacetone and phenol in the presence of hydrochloric acid at 100° give 1: 2: 2-tris-p-hydroxyphenyl propane. In our experiments, phenol reacted with chloroacetone in the presence of concentrated sulphuric acid at – 10° to – 5°, giving good yields of trans-4 ; 4′-dihydroxy-α -methylstilbene, but at higher temperatures the reaction tended to be very vigorous, yielding dark sulphur containing products. The diphenol and its diacetate and dimethyl ether were identical with the compounds synthesised earlier by Dodds et al. (Proc. Roy. Soc., 1944, B, 132, 83). Anisole and phenetole reacted similarly with chloroacetone, yielding 4 : 4′-dimethoxy- and ‘ 4; 4’-diethoxy-α-methylstilbencs, which were also prepared by alkylation of the diphenol. The same three products were also obtained, although in lower yields, when chloroacetone was condensed with phenol, anisole, or phenetole in the presence of aluminium chloride at -0°, with or without light petroleum as diluent.

When 3-chlorobutanone was used in place of chloroacetone, similar condensations occurred with phenol and anisole at 0°, yielding 2: 3-di-p-hydroxyphenylbut-2-ene (characterised as its diacetyl derivative) and its dimethyl ether respectively, also obtained by Dodds et al. (loc. cit.) .

In a preliminary note Bhargava and Zaheer (Nature, 1953, 171, 746) postulated a reaction mechanism involving a Friedel-Crafts type of reaction as the first step. Sastri, Shanmukha Rao, and Zaheer (Current Sci ., 1953, 22, 338), however, suggested a more probable reaction sequence, in which first the carbonyl group of the ketone reacts at the P-position of the aromatic compound, a subsequent rearrangement involving migration of one of the aromatic nuclei to the adjacent carbon atom and dehydrohalogenation.

Similar condensations with 2-chloropentan-3-one and 4-chlorohexan-3-one are being attempted with a view to synthesis of oestrogenic compounds.

HOW TO CITE

Reactions of alpha-halogenoketones with aromatic compounds – Part I: Reactions of chloroacetone and 3-chlorobutanone with phenol and its ethers. S H ZAHEER, P M BHARGAVA, B SINGH, B BHUSHAN, I K KACHKER, K RAMCHANDRAN, V D N SASTGRI & N S RAO. Journal of the Chemical Society, 1954, 3360-3362.

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