5-substituted aminophenols

Details 5-substituted aminophenols 5-substituted aminophenols

1989-07-17

1990-07-10

Hollrah, Glennon H.

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

Organic compounds

Carboxylic acid esters

560 13, 560 15, 562426, 562430, 564440, 548251, 548260, 548261, 548311, 558 13, 558179, 558184, C07C14713

Patent

active

049408127

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-enolizble 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: 3637803 (1972-01-01), Shen et al.
patent: 3779763 (1973-12-01), Lau
patent: 4242519 (1980-12-01), Tsuchihashi et al.
patent: 4741846 (1988-05-01), Evans
Philip T. S. Lau et al., J. Org. Chem., 28, 2763, (1963).

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