JPS591266B2 - Satsukarin no Seizou Hohou - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention oxidizes 0-toluenesulfonamide to produce
1,2-Benzisothiazolidine-3-one-1,1-
This invention relates to a method for producing carbon dioxide (hereinafter referred to as saccharin).

The purpose is to oxidize 0-toluenesulfonamide at low cost using an industrially simple reaction system. Saccharin obtained by oxidation of 0-toluenesulfonamide is an industrially important chemical as an additive for food sweeteners and polymer compounds.

Conventionally, electrolytic oxidation and chemical oxidation using dichromate or permanganate have been used to synthesize saccharin by oxidizing 0-toluenesulfonamide.

The former uses a diaphragm to obtain high purity products, but
Electricity consumption is large and the lifespan of the diaphragm is quite short.
It has the disadvantage of significantly increasing operating costs. In the latter case, the reaction and equipment are simple, but the method has problems in processing large amounts of oxidant waste liquid and removing heavy metals mixed in saccharin. In both cases, 0-sulfonamidobenzoic acid is obtained by oxidation, and in order to obtain saccharin, it is a two-step reaction that requires further cyclodehydration with an acid catalyst. The only attempt to synthesize saccharin from 0-toluenesulfonamide by autoxidation is disclosed in French Patent No. 2086539 (Lone Poulenc).

This method uses ketones as an initiator, and the added ketones are first oxidized with oxygen in the reaction system to form a peroxide, which is then used as an initiator. The ketones used are acetaldehyde (boiling point 21°C)
, ethyl methyl ketone (boiling point 79.6°C), etc., all have low vapor pressure and are easily entrained in exhaust gas and discharged from the system, requiring the use of a pressure cooker. Furthermore, all of the added ketones are not effectively autooxidized, and furthermore, oxidation products of ketones accumulate in the system. As a result of repeated research from the viewpoint of a method that can be industrially produced at low cost, the present inventors have discovered a method for obtaining saccharin through a one-stage reaction. That is, the method of the present invention is to prepare o-toluenesulfonamide in an acetic acid solvent, use a reduction metal salt such as cobalt or manganese as a catalyst, and ozone-containing oxygen or ozone-containing This is a method of producing saccharin by autooxidation by introducing air. 0-Toluenesulfonamide has a sulfonamide group, which is an electron-withdrawing group, at the ortho position, and also reduces the oxidation reactivity of the methyl group from the viewpoint of steric hindrance.

Therefore, when carrying out autoxidation, the selection of an initiator is important. Azobisisobutyronitrile, cumene hydroperoxide, t-butyl hydroperoxide, benzoyl peroxide, etc., which are commonly used as autooxidation initiators, cannot sufficiently initiate the reaction. The present inventors have arrived at the present invention by discovering that the above reaction can be effectively carried out in the presence of a transition metal salt catalyst using ozone as an initiator. The reaction solvent used in the method of the present invention is preferably a lower carboxylic acid such as acetic acid or propionic acid, with acetic acid being particularly preferred.

The amount used is about 10 to 150 mol, preferably about 20 to 100 mol, per 1 mol of the substrate. The catalyst is preferably a salt containing a transition metal, and particularly preferred is an acetate of CO() or Mn().

The amount used is about 0.005 to 2 mol, particularly preferably 0.01 to 0.8 mol, per 1 mol of the substrate. The reaction temperature may range from 5'C to the reflux temperature of the solvent, but is preferably 60 to 120C because the reaction rate is slow in low mud and by-products are produced at high temperatures. Although the reaction proceeds satisfactorily at normal pressure, favorable results can also be obtained under a pressure of about 15 atm. The amount of ozone used as an initiator is sufficient as long as it is contained in the oxygen or air used as an oxidizing agent in a very small amount to about 10-odd percent (by volume), preferably from 0.2 to 8% (by volume) relative to oxygen. ratio).

The oxidizing agent is air or oxygen, and the supply amount is 1
The total amount is about several tens of moles or more and several hundred moles based on the mole, and thereby the reaction solution can also be stirred. When supplying, the oxidizing agent can be introduced into the ozone generator and led directly to the reactor, or the oxidizing agent can be mixed with highly concentrated ozone to make a constant amount of ozone before being led to the reactor. But that's fine. In the method of the present invention, the oxidation system obtained by dissolving the substrate and transition metal salt catalyst in acetic acid and introducing ozone-containing oxygen is a very highly active oxidation system, with 0
-Toluenesulfonamide can be reacted to saccharin in one step.

In addition, in this case, since it is only necessary to include a small amount of ozone in the oxidizing agent, the conventional liquid phase auto-oxidation reaction equipment can be used as is, and furthermore, there is no need to perform a separate dehydration reaction. The method has various excellent features.

The method of the present invention will be specifically explained below using Examples and Comparative Examples.

Example-1 8.55 g of 0-toluenesulfonamide and 4.89 g of cobaltous acetate tetrahydrate were dissolved in 1009 acetic acid, and a cylindrical reaction tube (diameter 4 cTn1 35 cm in length), and at a reaction temperature of 100°C, 580 m1/Mi of oxygen containing 2% ozone (volume ratio) was added.
The mixture was introduced for 12 hours at a flow rate of n.

(At that time, an induction period of about 5 hours was observed.) After the reaction was completed, the reaction solution was concentrated and the acetic acid used as a solvent was removed to obtain crude saccharin. Add, stir well and filter.
Cobalt hydroxide was obtained as a filter cake. The filter cake is further washed with 5 ml of 4N caustic soda aqueous solution, and the washing liquid is combined with the filtrate. Add 15ml of distilled water to the filtrate and
When neutralized with a 20% aqueous hydrochloric acid solution, unreacted 0-toluenesulfonamide precipitates out, and further, P is neutralized with a 20% aqueous hydrochloric acid solution.
When the temperature was lowered to below H2, 4.4 g of saccharin was precipitated.
The unreacted 0-toluenesulfonamide obtained had a purity of 90% or more by gas chromatography;
The purity of Satucalin is 100% by gas chromatography.
%, and the yield based on the raw material was 48%. Example-2 8.559% of 0-toluenesulfonamide and 1.259% of cobaltous acetate tetrahydrate were dissolved in 1009% of acetic acid, and using the same reactor as in Example-1, 2% ozone was added at a reaction temperature of 100°C. Oxygen containing (volume ratio) at a flow rate of 580 m1/Mi
It was introduced at n.

After the reaction is completed, the reaction solution is concentrated, the acetic acid used as a solvent is removed, and 20 TLI of a 4N caustic soda aqueous solution is added to the obtained crude saccharin, stirred well and filtered to remove the used catalyst. 15 WL1 of distilled water was added to the filtrate, and the pH was adjusted to below 2 with a 20% aqueous hydrochloric acid solution to precipitate a total of 7.629 unreacted 0-toluenesulfonamide and saccharin. The content of saccharin is 7 in gas chromatography.
2%, the remainder being unreacted 0-toluenesulfonamide. The yield of saccharin based on the starting material was 66% after a reaction time of 7 hours, excluding the induction period. Example-3 8.55 g of 0-toluenesulfonamide and 2.49 g of cobaltous acetate tetrahydrate were dissolved in 100 g of acetic acid, and using the same reactor as in Example-1, ozone 7.
% (volume ratio) at a flow rate of 580 m1/Mi
It was introduced at n.

After the reaction was completed, the same post-treatment as in Example-2 was carried out, and a total of 7 saccharin and unreacted 0-toluenesulfonamide was
．． I got 05f1. The content of sacchulin by gas chromatography was 63%, with the remainder being unreacted 0-toluenesulfonamide. After a reaction time of 7 hours excluding the induction period, the yield of saccharin was 53% based on the starting material.
Example-4 0-Toluenesulfonamide 8.559 and cobaltous acetate tetrahydrate 2.49 were dissolved in acetic acid 1009, and using the same reactor as Example-1, ozone 2 was added at a reaction temperature of 7°C. %
Oxygen containing (volume ratio) was introduced at a flow rate of 580 ml/min.

After the reaction was completed, the same post-treatment as in Example-2 was carried out, and a total of 7 saccharin and unreacted 0-toluenesulfonamide was
．． I got 219. The content of sacculin by gas chromatography was 72%, with the remainder being unreacted 0-toluenesulfonamide. After a reaction time of 7 hours excluding the induction period, the yield of saccharin was 57-? It was hot.
Example-5 0-Toluenesulfonamide 8.55f! , 4.99% manganous acetate tetrahydrate was dissolved in 1009% acetic acid, and using the same reactor as in Example-1, oxygen containing 2% ozone (volume ratio) was added at a reaction temperature of 100°C at a flow rate of 580ml/Ml.
n for 10 hours.

After the reaction was completed, the same post-treatment as in Example-2 was carried out, and a total of 6 saccharin and unreacted 0-toluenesulfonamide was obtained.
．． 90g was obtained. The content of sacculin by gas chromatography was 47%, with the remainder being unreacted 0-toluenesulfonamide. Note that the yield of saccharin based on the raw material was 35%. Comparative Example-1 0-Toluenesulfonamide 3.559, cobaltous acetate tetrahydrate 4.89 and acetic acid 100f! Using the same reactor as in Example-1, at a reaction temperature of 108°C, 0.59% of 1-sozobisisobutyronitrile was dissolved as an initiator.
, 2 cumene hydroperoxide 1,59, 1.5 g of 3t-butyl hydroperoxide were added separately,
Oxygen was introduced at a flow rate of 580 ml/min for 10 hours.

After the reaction was completed, the same post-treatment as in Example 12 was carried out, and the products were fixed by gas chromatography. As a result, all of the products remained as raw materials, and no saccharin was produced. Comparative Example-2 8.55 g of 0-toluenesulfonamide and 4.89 g of cobaltous acetate tetrahydrate were dissolved in crocobenzene 1009, using the same reactor as in Example-1, and at a reaction temperature of 130°C.
When the temperature reached 0.59 ml of azobisisobutyronitrile, oxygen was introduced at a flow rate of 580 ml/min for 10 hours.

Claims (1)

[Claims] 1 In producing saccharin by oxidizing 0-toluenesulfonamide with molecular oxygen in the liquid phase, in the presence of cobalt acetate or manganese acetate,
A method for producing saccharin, characterized in that ozone is used as an oxygen initiator.