GB2127015A

GB2127015A - N-substituted carbonate and sulphonate esters of N-hydroxy-1,8- naphthalimide

Info

Publication number: GB2127015A
Application number: GB08320225A
Authority: GB
Inventors: Kamalakant Krishnarao Joshi
Original assignee: Imperial Chemical Industries Ltd
Current assignee: Imperial Chemical Industries Ltd
Priority date: 1982-08-23
Filing date: 1983-07-27
Publication date: 1984-04-04
Also published as: GB8320225D0

Abstract

A process for the preparation of the title compounds comprises reacting N-hydroxy-1,8-naphthalimide with an esterifying agent of the formula: X-Y-R (I> wherein: X is halogen, and either Y is =CO and R is halogen or lower alkoxy, or Y is =SO2 and R is lower alkyl, in an aqueous medium at a pH from 7 to 9. Products of this reaction: <IMAGE> wherein: R<1> lower alkoxy, halogen or N-oxy- 1,8-naphthalimide are claimed per se.

Description

SPECIFICATION Esterification process This specification describes an invention relating to a novel compound and a process for the preparation thereof which comprises a stage in the preparation of salts of 1-amino-8-naphthoic acid and naphtholactam from napththalic anhydride.

It is known to convert naphthalic anhydride into N-hydroxynaphthalimide by reaction with hydroxylamine and to esterify the product with, for example, toluene-4-sulphonyl chloride.

Naphtholactam is obtainable from the ester by saponification with sodium hydroxide and acidification of the sodium 1-amino-8naphthoate. The know methods generally require a substantially non-aqueous reaction medium and/or expensive esterifying agents which add significantly to the cost of the end product.

According to the present invention there is provided a process for the preparation of an Nsubstituted carbonate or sulphonate ester of N hydroxy-1 ,8-naphthalimide which comprises reacting N-hydroxy-1 ,8-naphthalimide with an esterifying agent of the formula: X-Y-R wherein X is halogen, Y is=CO and R is halogen or lower alkoxy or Y is=SO2 and R is lower alkyl, in an aqueous medium at a pH from 7 to 9.

The product of this reaction is:

wherein R1 lower alkoxy, halogen or N-oxy-1,8naphthalimide, and Y has the above defined meaning. The compound of Formula II wherein Y is C=O is a new compound and forms a second feature of the present invention.

The product of the process of the present invention may be converted into a salt of 1amino-8-naphthoic acid by saponification with a suitable base, e.g. sodium hydroxide, from which the lactam may be formed by acidification with a mineral acid.

It is generally preferred that X is chlorine and a preferred esterifying agent is methane sulphonyl chloride in which case R and R' are methyl, X is chlorine and Y is SO2. Another preferred esterifying agent is ethyl chloroformate which forms one of the novel species of the compound of Formula II in which Y is C=O, in which case R and R1 are OC2Hs and X is chlorine. Another possible esterifying agent is phosgene, in which case R and X are chlorine and R' is chlorine or a second N-oxy-1 ,8-naphthalimide radical. The weakly alkaline conditions may be achieved by the use of a suitable base, e.g. dilute sodium hydroxide.Esterification is conveniently performed at or around the ambient temperature, i.e. 20 to 400 C, although higher temperatures up to the boiling point of the reaction medium may be employed.

The invention, in all its aspects, is further illustrated by the following Examples in which, unless otherwise indicated, all parts and percentages are by weight.

Example 1 (a) Preparation of N-hydroxynaphthalimide In a 1 litre three-necked flask equipped with a stirrer and thermometer, a suspension of naphthalic anhydride (59.49) and hydroxylamine sulphate (24.6g) in water (4209) was prepared.

After warming the mixture ot 350C an 8% aqueous solution of sodium hydroxide (1629) was added over 30 minutes. After holding the reaction mixture for a further 30 minutes, a further 1 62g of the 8% aqueous sodium hydroxide solution was added. The reaction mixture then contained the sodium salt of N-hydroxynaphthalimide.

(b) Preparation of ethyl naphthylimidocarbonate To the solution of N-hydroxynaphthalimide prepared in (a) above there was added 32.69 of ethyl orthochloroformate. An exotherm was observed and a yellow-buff precipitate was formed. After cooling to ambient temperature the pH was ajusted to 7 with sodium carbonate. The product (79.4g, yield: 92.9%) was isolated by filtration and washing.

Example 2 Preparation of bis-naphthylimidocarbonate To a solution of the sodium salt of Nhydroxynaphthalimide at 35"C, prepared as in Example 1 (a) using 56g of naphthalic anhydride and the other ingredients scaled down accordingly, was added 1 4g of phosgene. A white solid rapidly precipitated. This was confirmed to be bis-naphthylimido carbonate.

Example 3 Preparation of naphthylimidomethanesulphonate To a solution of the sodium salt of Nhydroxynaphthalimide at 350C, prepared as in Example 1 (a) using 79.2g of naphthalic anhydride and the other ingredients scaled up accordingly, was added 45.69 of methane sulphonyl chloride, resulting in an exotherm of 30C. A buff precipitate was formed which was isolated by filtration and washed with water to give 1089 (yield: 92.8%) of product.

Claims

1. A process for the preparation of an Nsubstituted carbonate or sulphonate ester of N

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Esterification process This specification describes an invention relating to a novel compound and a process for the preparation thereof which comprises a stage in the preparation of salts of 1-amino-8-naphthoic acid and naphtholactam from napththalic anhydride. It is known to convert naphthalic anhydride into N-hydroxynaphthalimide by reaction with hydroxylamine and to esterify the product with, for example, toluene-4-sulphonyl chloride. Naphtholactam is obtainable from the ester by saponification with sodium hydroxide and acidification of the sodium 1-amino-8naphthoate. The know methods generally require a substantially non-aqueous reaction medium and/or expensive esterifying agents which add significantly to the cost of the end product. According to the present invention there is provided a process for the preparation of an Nsubstituted carbonate or sulphonate ester of N hydroxy-1 ,8-naphthalimide which comprises reacting N-hydroxy-1 ,8-naphthalimide with an esterifying agent of the formula: X-Y-R wherein X is halogen, Y is=CO and R is halogen or lower alkoxy or Y is=SO2 and R is lower alkyl, in an aqueous medium at a pH from 7 to 9. The product of this reaction is: wherein R1 lower alkoxy, halogen or N-oxy-1,8naphthalimide, and Y has the above defined meaning. The compound of Formula II wherein Y is C=O is a new compound and forms a second feature of the present invention. The product of the process of the present invention may be converted into a salt of 1amino-8-naphthoic acid by saponification with a suitable base, e.g. sodium hydroxide, from which the lactam may be formed by acidification with a mineral acid. It is generally preferred that X is chlorine and a preferred esterifying agent is methane sulphonyl chloride in which case R and R' are methyl, X is chlorine and Y is SO2. Another preferred esterifying agent is ethyl chloroformate which forms one of the novel species of the compound of Formula II in which Y is C=O, in which case R and R1 are OC2Hs and X is chlorine. Another possible esterifying agent is phosgene, in which case R and X are chlorine and R' is chlorine or a second N-oxy-1 ,8-naphthalimide radical. The weakly alkaline conditions may be achieved by the use of a suitable base, e.g. dilute sodium hydroxide.Esterification is conveniently performed at or around the ambient temperature, i.e. 20 to 400 C, although higher temperatures up to the boiling point of the reaction medium may be employed. The invention, in all its aspects, is further illustrated by the following Examples in which, unless otherwise indicated, all parts and percentages are by weight. Example 1 (a) Preparation of N-hydroxynaphthalimide In a 1 litre three-necked flask equipped with a stirrer and thermometer, a suspension of naphthalic anhydride (59.49) and hydroxylamine sulphate (24.6g) in water (4209) was prepared. After warming the mixture ot 350C an 8% aqueous solution of sodium hydroxide (1629) was added over 30 minutes. After holding the reaction mixture for a further 30 minutes, a further 1 62g of the 8% aqueous sodium hydroxide solution was added. The reaction mixture then contained the sodium salt of N-hydroxynaphthalimide. (b) Preparation of ethyl naphthylimidocarbonate To the solution of N-hydroxynaphthalimide prepared in (a) above there was added 32.69 of ethyl orthochloroformate. An exotherm was observed and a yellow-buff precipitate was formed. After cooling to ambient temperature the pH was ajusted to 7 with sodium carbonate. The product (79.4g, yield: 92.9%) was isolated by filtration and washing. Example 2 Preparation of bis-naphthylimidocarbonate To a solution of the sodium salt of Nhydroxynaphthalimide at 35"C, prepared as in Example 1 (a) using 56g of naphthalic anhydride and the other ingredients scaled down accordingly, was added 1 4g of phosgene. A white solid rapidly precipitated. This was confirmed to be bis-naphthylimido carbonate. Example 3 Preparation of naphthylimidomethanesulphonate To a solution of the sodium salt of Nhydroxynaphthalimide at 350C, prepared as in Example 1 (a) using 79.2g of naphthalic anhydride and the other ingredients scaled up accordingly, was added 45.69 of methane sulphonyl chloride, resulting in an exotherm of 30C. A buff precipitate was formed which was isolated by filtration and washed with water to give 1089 (yield: 92.8%) of product. Claims

1. A process for the preparation of an Nsubstituted carbonate or sulphonate ester of N hydroxy-1 ,8-naphthalimide which comprises reacting N-hydroxy-1 ,8-naphthalimide with an esterifying agent of the formula: X-Y-P wherein Xis halogen and Y is=CO and R is halogen or lower alkoxy or Y is=SO2 and R is lower alkyl, in an aqueous medium at a pH from 7 to 9.

2. A process according to Claim 1 wherein the esterifying agent is ethyl chloroformate, methane sulphonylchloride or phosgene.

3. A process according to Claim 1 or Claim 2 performed at a temperature from 200C to 400 C.

4. A process as described in any one of the Examples.

5. A compound of the formula:

wherein R' lower alkoxy, halogen or N-oxy-1,8naphthalimide.

6. The compound of Claim 5 wherein R' is ethoxy.