HU180500B - Process for preparing piperonyl-buthoxide - Google Patents

Description

Process for the preparation of piperonyl butoxide

2

The present invention relates to a process for the preparation of piperonyl butoxide. SUMMARY OF THE INVENTION It is an object of the present invention to overcome the drawbacks of the known processes by employing a process for the production of piperonyl butoxide in a higher yield and purity economically.

Piperonyl butoxide is a synergist of pyrethroid insecticides, which are the most valuable, fast-acting insecticides for humans and warm-blooded animals. The toxicity of piperonyl butoxide to mammals is as low as that of pyrethroids.

Technical grade piperonyl butoxide contains 80% active ingredient, α- [2- (2-butoxyethoxy) ethoxy] -4,5- (methylenedioxy) 2-propyl toluene. The industrially usable preparation is generally carried out according to Scheme A.

The starting material of the process is safrole, which is the main constituent of naturally occurring sassafras oil and camphor oil. It is hydrogenated, chloromethylated and condensed with Na-alcohol (Na-butylcarbitolate) of diethylene glycol monobutyl ether.

Due to the food industry's use for piperonyl butoxide, it is essential that the product does not contain toxic ₍ eg Cl-containing) impurities.

The second step in the production technology is chloromethylation. Formaldehyde or paraformaldehyde is carried out using 180500 brine, concentrated hydrochloric acid or hydrogen chloride gas, which are added in excess to effect the reaction. After the chloromethyl and condensation and polymerization products of paraformaldehyde and excess hydrochloric acid, the solution must be removed from the system, which is solved in various ways by known methods.

H. Wachs, $ 2,485,680, $ 2,485,681, and $ 2,550,737. According to U.S. Patents, after the chloromethylation reaction, the oily layers are separated and the aqueous layer is extracted with benzene. The benzene solution and the separated oil are combined and neutralized with NaHCO ₃ solution. The solution is dried, the benzene is distilled off and the residual oil is vacuum distilled from which chloromethyl dibidrosafrol is distilled at 4 mm Hg at 128 ° C. According to the patents, the disadvantage of chloromethylation is the long reaction time of 36 hours and the difficult processing of chloromethyl dihydro-rosafrole.

No. 227,102. According to the Australian Patent (Chem. Zbl. 1962. 6184), after 4 hours of chloromethylation at 80 [deg.] C., the yield of the resulting oil layer is 97% based on the content of chloromethyl dihydrosafrol in the resulting oil layer. No reference to product processing was found. The author determines the chloromethylation yield on the basis of the total chlorine content determination, but here the HC1 remaining in the system can be disturbing.

Japanese Procedure [J. Agric. Chem. Soc. Japan 1

35, 91-5 (1961)] using chlorine or sulfuric acid as the catalyst for chloromethylation and the reaction is carried out in benzene or glacial acetic acid. The reaction product is extracted with ether, the ether solution is washed with Na carbonate solution and then with saturated NaCl solution, the ether is distilled off and the resulting product is purified by fractional distillation. A disadvantage of this process is the use of flammable ether during product processing.

A 2,485,680; 2,485,681; and U.S. Patent Nos. 2,550,737 to Diethylene glycol monobutyl ether-Na are prepared in a benzene solvent by refluxing in excess diethylene glycol monobutyl ether and NaOH. During the condensation, the alcoholate and chloromethyl dihydrosafrole are refluxed for 4 hours after standing overnight in benzene solvent. The patented 4-step process has an efficiency of 30%.

According to a Soviet statement [B. Lurik B. et al., Med. SSSR. 19, (3) 14-17 (1965)] chloromethylated with excess hydrochloric acid and paraformaldehyde. The resulting mixture was washed with water, soda solution and water again to neutrality and then distilled under vacuum. After the condensation of chloromethyl dihydrosafrol and diethylene glycol monobutyl ether, Na, the NaCl precipitated is dissolved in water, the organic layer is washed with weak acetic acid and then with water until neutral and subjected to vacuum distillation. The efficiency of the process, calculated on safrole, is 37%.

Polish procedure [Fabrycy Aindrzej et al .:

Przed. Chem. 1971 50 (3) 173] for chloromethylation of paraformaldehyde, cc. HCl and hydrogen chloride gas are bubbled through, resulting in 90% efficiency for chloromethylation and 60% for condensation. However, no mention is made of product processing.

In another procedure, [U.S. Chloromethyldihydrosafrole is not prepared in a separate step, but is reacted with diethylene glycol monobutyl ether, paraformaldehyde and dihydrosafrole in the presence of a p-toluenesulfonic acid catalyst. The disadvantage of the process is that the reaction requires a reaction time of 3 days.

The downside of the known piperonyl butoxide preparations, the complexity of product processing and the low yields of total processing. During the four-step synthesis, the reaction mixture has to be washed twice to neutralize to remove paraformaldehyde and excess hydrochloric acid after chloromethylation, and to remove NaCl formed after the condensation and excess diethylene glycol monobutyl ether-Na. In most cases, the removal of excess paraformaldehyde and hydrochloric acid is accomplished by extraction and neutralization with sodium hydroxide solution. The NaCl is removed by washing with water, during which part of the excess diethylene glycol monobutyl ether is also added to the wash water.

The acid-free washing after chloromethylation is carried out by washing with aqueous soda solution, while the chloromethyl dihydrosafrol is hydrolyzed, which results in a reduction in yield and the formation of the following structure (I):

^Η7ε3 ίοΓ ^θ

CH ₂ -O-CH ₂ CH,

Cl 3, much of which, when dissolved in chloromethyl dihydrosafrole, is passed on to the condensation reaction and finally to the crude piperonyl butoxide, which cannot be removed since its boiling point is ca. It differs from piperonyl butoxide by 10 ° C.

In our experimental work, we developed a gas chromatographic assay for chloromethyl dihydrosafrol and piperonyl butoxide, which, after identification of the contaminating components, was able to create chloromethylation and subsequent coupling reaction conditions that minimize the to.

It has been found that, if the chloromethylation reaction is carried out at a higher temperature (80-95 ° C), the formation of dichloromethylated derivatives is more potent, which will also participate in the subsequent reaction and increase the higher boiling impurities of PBO and reduce the yield of the useful product. . In the prior art, this side reaction occurs due to the higher chloromethylation temperature but is not detected due to the lack of a suitable analytical method. Therefore, by determining the total chlorine content, a higher concentration of chloromethyl dihydrosafrol and a higher yield.

It has also been found that the use of an incorrect molar ratio of hydrochloric acid to paraformaldehyde results in the formation of the following by-product of formula (II):

ch ₂

C2J

Due to their physical properties (boiling point, solubility), the harmful by-products resulting from improperly conducted chloromethylation and subsequent product processing are difficult to distinguish from chloromethyl-dihydrosafrole and later from piperonyl butoxide.

Of the various chemical technology steps in piperonyl butoxide production, chloromethylation is the one that most determines yield and quality. Therefore, the favorable design of this step and the processing of the product have resulted in the piperonyl butoxide being obtained in a purity of 85-90%, starting from 65% to 70% of the starting safrole, after a suitable molar ratio coupling reaction and conventional distillation. .

For this, it is essential that the chloromethyl dihydrosafrole can be prepared in a purity of 85-90% with a yield of about 90% (based on dihydrosafrole). In the practice, the hydrogenated and distilled sassafras oil was chloromethylated with hydrochloric acid and paraformaldehyde in a molar ratio of 1: 5 to 6: 1.6 to 1.8 at 40-60 ° C. The reaction mixture was separated from the aqueous hydrochloric acid by settling and was acidified and dehydrated by distillation under vacuum at 50-150 mmHg at 70-90 ° C. This product was reacted with free alkaline diethylene glycol monobutyl ether-Na at a molar ratio of 1: 1.4 at 120-130 ° C, and the reaction product was washed with water, after washing with salt and alkaline, vacuum distilled and vacuum evaporated in a film rotary evaporator. maradékmentesítettük.

in summary, the essence of our process is that of the technological step that most determines quality and yield; 1) Chloromethylation at lower temperatures avoids the formation of di- and trichloromethyl salts; and 2) Minimized formation of the "dimer" product (II) can be minimized with a well formed paraformaldehyde hydrochloric acid molar ratio and 3) hydrolysis of dihydrosafrol and formation of the "hydrolysis" product (I). As a result of these changes, both the purity of the product and the yield are increased to such an extent that the yield of piperonyl butoxide, calculated on safrole, can reach 65-70%.

The process of the present invention is illustrated by the following examples:

Example 2

Into a 1000 ml flask equipped with a stirrer, a reflux condenser and a thermometer, 185 g of hydrogenated distilled sassafras oil containing 90% dihydrosafrole (1 mol) and 600 g of cc were weighed. HCl (6 mol)) and 51 g (1.7 mol) of paraformaldehyde. The mixture is then stirred at 40 ° C for 3 hours and then at 60 ° C for 1 hour and sedimented in a separatory funnel. After separation of the aqueous-acidic portion, the organic phase is distilled off under vacuum (50-150 mmHg) to remove water and acid. Analytical data of the crude product thus obtained:

Weight: 220 g

Dihydrosafrol: 0%

Chloromethyl dihydrosafrol: 88.2% d-Chloromethyl-dihydrosafrol: 1.7% Dimer: 4.8%

Terpene: 5.3%

Yield: 91.5%

Example 2

Into a 1000 ml flask fitted with a stirrer, reflux condenser, thermometer and addition funnel, add 185 g of hydrogenated distilled sassafras oil containing 90% dihydrosafrole (1 mol) and add at 60 ° C, with stirring, at 60 ° C. mixed 500 g cc. HCl (5 mol) and 54 g (1.8 mol) of paraformaldehyde. The addition was carried out for 1 hour followed by a 2 hour post-reaction. At the end of the reaction, the reaction product is worked up as described in Example 1.

Weight: 225 g

Dihydrosafrol: 0%

Chloromethyldihydrosafrol: 85.7% dichloromethyldihydrosafrol: 4.5% Dimer: 6.4%

Terpene: 3.4%

Yield: 91%

Example 3

Into a 1000 ml flask equipped with a stirrer, a distillation flask, a thermometer and a addition funnel, add 520 g of diethylene glycol monobutyl ether and add 176 g of 45% NaOH under constant stirring at 100-110 ° C at 50-200 mmHg. solution at such a rate that no foaming or temperature decrease occurs. Meanwhile, the water introduced with sodium hydroxide and the alcohol formed during distillation are distilled. The reaction is then allowed to react for 1-2 hours and a solution of diethylene glycol monobutyl ether (65% to 70%) in diethylene glycol monobutyl ether-Na is obtained, which is reacted with chloroethyl dihydrosafrole for further reaction.

Analysis Data:

Weight of the product: 550 g

Alcohol content: 67.3%

Free Alkaline Content: 0.05%

Example 4

Weigh 400 g of 65% alcohol (1.4 mol) into a 1000 ml flask equipped with a stirrer, reflux condenser, thermometer and addition funnel.

Diethylene glycol monobutyl ether-Na prepared according to Examples 1 or 2 and 250 g of 85% (1.0 mole) of chloromethyl dihydrosafrole obtained in Example 1 or 2 are added with stirring at 120-130 ° C. After the addition, this reaction is followed by a reaction for 2-3 hours, and after cooling at 50-60 [deg.] C., it is washed 3-4 times with the same amount of water, precipitated, separated and finally dried over 100-50 mmHg. The crude anhydrous product is vacuum distilled and evaporated to a residue.

180 300

Analysis Data:

Weight of anhydrous crude product: 425 g

PBO content: 63.7% Weight of distillate: 90 g Weight of main spirit: 295 g Residual weight: 40 g

PBO content: 1.8% 10

PBO Hold: 92.0%

PBO Hold: 0.8%

The yield of the main distillate was 69.8% (based on 96% hydrogenation efficiency) of the piperonyl butoxide calculated on the starting safrole.

Claims (1)

A process for the preparation of piperonyl butoxide from essential oils containing safrole by chloromethylation of the essential oils of safrole with paraformaldehyde in the presence of hydrochloric acid and condensation of the chloromethylated product to piperonyl butoxide, characterized in that Chloromethylation with 1.8 mol of paraformaldehyde, the reaction product mixture was separated from the aqueous hydrochloric acid by settling and acidified and dehydrated by distillation under vacuum at 50-150 mmHg at 70 ° C to give a known product of diethylene glycol monobutyl ether. condensed to piperonyl butoxide.