Process for preparing 5-substituted aminophenols

Details Process for preparing 5-substituted aminophenols Process for preparing 5-substituted aminophenols

1990-04-13

1991-08-27

Raymond, Richard L.

Organic compounds -- part of the class 532-570 series

Organic compounds

Carboxylic acid esters

548251, 548260, 548301, 558 13, 558169, 560 16, 560 17, 560108, 560251, 562426, 562452, 562430, 564 92, 564162, 564184, 564221, 564409, 564440, C07C31504, C07C20978, C07C31914

Patent

active

050434691

ABSTRACT:
Process for the introduction of functional or functionalizable substituents para to the amino group in 2-aminophenols and 3-aminophenols. The process proceeds in one step, with substitution occurring selectively at the position para to the amino group. Consequently, the reaction is surprisingly straightforward, with very little or no contamination by isomeric by-products. The process comprises reaction of (a) an aminophenol having an open para position to the amino function, with (b) an unhindered non-enolizable aldehyde, and (c) a thiol or sulfinic acid which acts as a nucleophile. In preferred embodiments, the process is conducted at a temperature of from about 50.degree. C. to about 100.degree. C., and in the presence of a polar solvent. The reaction is promoted by an acid having sufficient acidity to protonate the amino group of the aminophenol. Preferably, the acid promoter is a mineral acid, and it is present in an amount at least substantially equivalent to the amount of aminophenol reactant. The promoter can be added as a salt of the aminophenol.

REFERENCES:
patent: 3779763 (1973-12-01), Lau
Chemical Abstracts, vol. 64, No. 3, Jan. 31, 1966, col. 3471 a-c, "Reactions of Anils with Vinyl Butyl Sulfide", Povarov et al.
Grillot et al., "Condensation of Throphenols and Formaldehyde with Some Aromatic Amines", CA 54,5530i, 1960.

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