Propoxur CAS 114-26-1 Baygon

Proxacarb is a carbamate insecticide, which is mainly used for the control of economic crop pests and the elimination of various sanitary pests in households and public places. It has the characteristics of wide insecticidal spectrum, long residual effect and high insecticidal rate.

At this stage, there are three methods of synthesizing propoxur:

1. Chloroformate method, the method process is more complicated;

2. Methylcarbamoyl chloride method, which has serious environmental pollution;

3. Methyl isocyanate method, although this method has simple process flow and less three wastes, the reaction yield is generally below 90%:

In a glass reactor, add o-isopropoxyphenol and catalyst, n (phenol): n (catalyst) = 1: 0.001 ~ 0.05; stir and cool, slowly add methyl isocyanate (MIC), n (phenol) : n(MIC)=1:1～1:1.2; after the dropwise addition, the reaction is carried out at 60～110° C. for 0.5～3h.

Propoxur itself has no odor, but there are about 1% of 1,2-diisopropoxybenzene and 0.1% of 1-isopropoxy-2-methoxybenzene and other aromatic ethers in the original drug of propoxur ( All come from the main raw material 2-isopropoxyphenol) with a special unpleasant odor, which affects the indoor use of propoxur as a high-grade sanitary insecticide. Therefore, it is necessary to develop a simple and effective separation technology for the purification of propoxur , 1,2-diisopropoxybenzene (diether) and 1-isopropoxy-2-methoxybenzene and other substances were removed from the crude product.

ZL98112498.4 adopts the solvent recrystallization method to dissolve 97% propoxur in 2 times the volume of 50% ethanol aqueous solution by heating, then crystallize, filter and dry. This process can obtain 99% propoxur with a yield of 96%. This method needs to use a lot of solvents, and propoxur has poor stability in an aqueous ethanol solution, and will be partially decomposed in the process of heating dissolving and solvent distillation recovery, and the energy consumption during solvent recovery is relatively large.

The modified purification method is as follows:

Add 214.4g propoxur (97.5%) and 8.5g petroleum ether to the 500mL three-necked flask with cooling tube, thermometer and stirring, stir and heat to 95°C to complete melting, and control the temperature of the system to slowly drop to 85°C (cooling rate 0.1°C/ min) and maintained for 1 h, standing for crystallization. A small amount of yellow liquid appeared in the kettle and floated above the white solid, which was removed from the system. The white solid was heated and melted and sliced ​​to obtain 205.2 g of propoxur (liquid chromatography, external standard) with a content of 99.3% white and odorless (liquid chromatography, external standard) with a yield of 97.5%.

The mass of the yellow liquid removed from the system was 15.8 g, which was analyzed as a 32.5% propoxur solution in petroleum ether, and 1,2-diisopropoxybenzene and 1-isopropoxy-2-methoxybenzene were also dissolved. 6g of petroleum ether can be recovered by simple distillation, and the remaining ointment residue after distillation can be incinerated.