WO1993022300A1

WO1993022300A1 - Process for the production of 2-phenyl-benzoxazin-4-one

Info

Publication number: WO1993022300A1
Application number: PCT/GB1993/000822
Authority: WO
Inventors: Michael Lancaster
Original assignee: BP Chemicals Ltd
Current assignee: BP Chemicals Ltd
Priority date: 1992-04-23
Filing date: 1993-04-20
Publication date: 1993-11-11
Anticipated expiration: 1994-10-23

Abstract

This invention relates to a process for the production of compounds of the 2-phenyl-benzoxazin-4-one (2PB4) type by reacting the corresponding isatoic anhydride with benzoic anhydride at elevated temperature, optionally in the presence of a solvent. The process has the advantage that the reaction is carried out without resorting to the use of acid halides or nitrogeneous bases. The 2PB4 type products are useful as bleach activators.

Description

PROCESS FOR THE PRODUCTION OF 2-PHENYL-BENZ0XAZIN-4-0NE

The present invention relates to a process for the production of compounds of the 2-phenyl-4H-3,l-benozoxazin-4-one (hereafter "2PB4") type directly from the corresponding isatoic anhydride without having to resort to the use of acid halides or nitrogenous bases.

It is well known to produce 2PB4 from isatoic anhydride either by reaction thereof with benzoyl halides in the presence of a strong base or with benzoic anhydride in the presence of an organic base such as a tertiary amine (see USP 3989698) . It is also known that acid halides such as benzoyl chloride or tertiary amine bases such as pyridine or piperidine used in such reactions are not particularly user-friendly and are difficult to handle. Moreover, the use of acid halides can give rise to corrosive by-products and hence the capital cost of any commercial plant will increase significantly if the corrosive effects of strong acids or alkalis are to be minimised. In addition, such acid halides and nitrogenous bases generate chloride ion or nitrogen containing by-products which are difficult to dispose of and can be harmful to the environment. It has now been found that the use of acid halides or nitrogenous bases for producing compounds of the 2PB4 type can be avoided by choice of suitable reactants and reaction conditions.

Accordingly, the present invention is a process for the production of compounds of the 2PB4 type, said process comprising reacting the corresponding isatoic anhydride with benzoic anhydride at elevated temperature in the absence of a base, optionally in the presence of a solvent.

Isatoic anhydride is a well established chemical and can be obtained commercially in high grades of purity. By the expression "2PB4 type" is meant here and throughout the specification the basic 2PB4 structure as defined herein above and any nuclear substituents groups carried by the basic structure which do not interfere with the reaction of producing a benzoxazinone structure from benzoic anhydride and the corresponding isatoic anhydride. Such substituent groups may be one or more of alkyl, aryl, alkaryl, aralkyl groups or halogen atoms. It will be understood by those skilled in the art that in order to produce a 2PB4 type structure which carries such substituents, the starting isatoic anhydride must also carry the corresponding substituents in its nucleus.

The reaction between isatoic anhydride and benzoic anhydride is suitably carried out in the presence of a solvent although this is not essential. A solvent, when used, is suitably a ketone such as methyl ethyl ketone, a carboxylic acid such as acetic acid, a nitrile such as a benzonitrile, an ester such as methyl benzoate or a diglyme and is preferably diglyme.

The mol ratio of isatoic anhydride to benzoic anhydride in the latter reaction is suitably in the range from 1:1 to 1:3, preferably in the range from 1:1 to 1:1.5. Substantially equimolar amounts of the reactants is most preferred.

In this reaction the reactants are suitably mixed with the solvent and refluxed for a duration at a temperature in the range from 100°C to 250°C, preferably in the range from 120° to 200°C.

The main by-product of this reaction is benzoic acid which can be separated from the desired 2PB4 type product by conventional techniques, eg distillation.

2PB4 type products are very desirable because they can be used as a bleach activator in detergent formulations as claimed and described in our published EP-A-332294. They enhance the low temperature bleaching activity of conventional bleaches. The process of the present invention is further illustrated with reference to the following Examples: Example 1 (Isatoic Anhydride + Benzoic Anhydride in Diglyme) :

Isatoic anhydride (10g, 0.06 mol) and benzoic anhydride (14g, 0.06 mol) were mixed together in diglyme (50 ml) and refluxed for 2 hr (ca. 160°C) . Subsequent work-up showed some unreacted isatoic anhydride (ca. lOXw/w) ; the rest of the reaction mixture comprised 2PB4 and benzoic acid, which was not separated. The reaction achieved a conversion of 90% w/w. Example 2 (Isatoic Anhydride + Benzoic Anhydride) :

Isatoic anhydride (8.2g, 0.05 mol) and benzoic anhydride (12.6g, 0.06 mol) were heated gradually with continual stirring over a 1 hr period to 130°C and then reacted for a further 2.5 hr after which time all the isatoic anhydride had appeared to dissolve. Proton and 13c NMR showed only 22 w/w isatoic anhydride left in the mixture after this duration, the rest being benzoic acid and 2PB4. A small amount of unreacted benzoic anhydride (5%w/w) was also present in the product. The conversion in this case was 98Xw/w and the yield of 2PB4 was 95Xw/w. In both these Examples, the following peaks were observed in the NMR spectra for 2PB4 and benzoic acid:

A. 2PB4: δ - 8.25 (2H,m); 8.18 (lH,m) ; 7.76 (lH,m) ; 7.62 (lH,m); and 7.47 (4H,m).

B. Benzoic acid: d - 11.7 (lH,b) ; 8.15 (2H,m) ; and 7.55 (3H,m) . The above results show that 2PB4 can be produced without the use of acid halides or nitrogenous bases.

Claims

1. A process for the production of compounds of the 2PB4 type said process comprising reacting the corresponding isatoic anhydride with benzoic anhydride at elevated temperature in the absence of a base, optionally in the presence of a solvent.

2. A process according to Claim 1 wherein the solvent when used is selected from a ketone, a carboxylic acid, a nitrile, an ester and a diglyme.

3. A process according to Claim 2 wherein the solvent is selected from methylethyl ketone, acetic acid, benzonitrile, methyl benzoate and diglyme.

4. A process according to any one of the preceding Claims wherein the mol ratio of the corresponding isatoic anhydride to benzoic anhydride in the reaction is in the range from 1 : 1 to 1 : 3.

5. A process according to Claim 4 wherein the mol ratio of the corresponding isatoic anhydride to benzoic anhydride in the reaction is in the range from 1 : 1 to 1 : 1.5

6. A process according to any one of the preceding Claims wherein the reaction is carried out at a temperature in the range from 100-250°C.

7. A process according to Claim 6 wherein the reaction is carried out at a temperature in the range from 120-200°C.

8. A process according to any one of the preceding Claims wherein the 2PB4 type product is separated from the reaction mixture by distillation.

9. A process according to any one of the preceding Claims wherein 2PB4 is produced by reacting isatoic anhydride with benzoic anhydride at elevated temperature .