# US 4,393,235 A · Process for producing p-hydroxyphenyl/acetic acid

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- Number: US 4,393,235 A
- Document ID: US4393235A
- Status: Granted
- Kind: A
- Application number: 06/259,925
- Filed: 1981-05-04
- Granted: 1983-07-12
- Earliest claimed: 1980-06-11
- Assignees: Imperial Chemical Industries PLC
- Inventors: Alan Mitchell; Thomas Bailey
- Web page: https://patentgrep.com/patent/US4393235A

## CPC

- C07C 51/377: by splitting-off hydrogen or functional groups; by hydrogenolysis of functional groups {(C07C51/36 - C07C51/373 take precedence)}
- C07C: ACYCLIC OR CARBOCYCLIC COMPOUNDS

## Abstract

A process for the preparation of p-hydroxyphenylacetic acid by reducing p-hydroxymandelic acid with a stannous salt. The product is a valuable intermediate for the preparation of the .beta.-adrenergic blocking agent atenolol.

## Claims

### Claim 1

A process for the manufacture of p-hydroxyphenylacetic acid which comprises reducing p-hydroxymandelic acid with a stannous salt under acidic conditions, the reduction being carried out in aqueous solution in the presence of a mineral acid at a temperature of up to 100.degree. C.

### Claim 2 (depends on 1)

A process as claimed in claim 1 wherein the mineral acid is hydrochloric acid.

### Claim 3 (depends on 2)

A process as claimed in claim 2 which is carried out at a temperature of between 80.degree. and 85.degree. C.

### Claim 4 (depends on 1)

A process as claimed in claim 1 wherein the p-hydroxymandelic acid used as starting material is provided in the form of the monohydrate of its sodium salt.

### Claim 5 (depends on 1)

A process as claimed in claim 1 wherein the stannous salt is stannous chloride and the p-hydroxyphenylacetic acid is obtained in the form of a wet paste which is converted directly to p-hydroxyphenylacetamide without first drying and isolating the p-hydroxyphenylacetic acid.