Determination of the optimal conditions for the synthesis of O,O-diethyl O-nitrolignothiophosphate
Abstract Generated abstract
This study examines the synthesis of O,O-diethyl O-nitrolignothiophosphate from nitrated technical lignin and O,O-diethyl chlorothiophosphate in an aqueous alkaline medium. The authors varied reagent ratios, sodium hydroxide, pyridine, reaction time, and temperature, then characterized the products by phosphorus and sulfur content and evaluated insecticidal activity by time to complete housefly mortality. The most active preparation contained about 5.2 to 5.3% phosphorus, 5.5 to 5.8% sulfur, and 2.13% nitrogen, producing complete mortality in 10 minutes. The reported optimal conditions used 100 g nitrolignin, 40 g sodium hydroxide, 700 ml water, 12.6 ml pyridine, and 136.8 g diethyl chlorothiophosphate at 92 to 95°C for 2 hours.
Full Text
DETERMINATION OF THE OPTIMAL CONDITIONS FOR THE SYNTHESIS OF O,O-DIETHYL-O-NITROLIGNO-THIOPHOSPHATE
B. V. TRONOV, L. A. PERSHINA, A. A. KOVALENOK
(Presented by the organic section of the scientific-methodological seminar of the CTF)
The hydroxyl groups of lignin and its derivatives, in an amount of 20%, enter into an esterification reaction with O,O-diethyl chlorothiophosphate in a toluene medium, with heating for 2 hours [1, 2]. The compounds obtained possess a rather strong insecticidal action, especially the preparation obtained from nitrolignin.
In the present work, the influence of the amounts of starting substances, alkali, pyridine, reaction time, and temperature on the insecticidal action of O,O-diethyl-o-nitrolignothiophosphate was studied.
As a basis, the industrial aqueous method for obtaining thiophos was chosen [3].
Technical lignin from the Krasnoyarsk hydrolysis plant was taken as the starting raw material. The lignin was nitrated under the conditions proposed by N. N. Shorygina and co-workers [4].
The nitrolignin obtained contained 4.2% nitrogen; 10.9% carboxyl groups; 5.95% hydroxyl groups.
O,O-diethyl chlorothiophosphate was obtained by the method of Fletcher [5].
In the products obtained, sulfur [6] and phosphorus [7] were determined, and in preparation No. 115 carbon, hydrogen, and nitrogen were determined.
Into a round-bottom flask with a reflux condenser, stirrer, and dropping funnel were placed a weighed portion of nitrolignin; an alkali solution in the amount necessary to replace the hydrogens of the hydroxyl and carboxyl groups; 100 ml of water; and pyridine.
Then the contents of the flask were heated to a definite temperature. Upon reaching the necessary temperature, diethyl chlorothiophosphate was added dropwise over 20–30 min. The reaction mixture was heated with stirring for a specified period of time, then cooled; the precipitate was washed with water until a negative reaction for Cl′ and with hot toluene until a negative reaction for \(\mathrm{PO}_4^{III}\).
The amounts of starting products, synthesis conditions, analysis of the preparations obtained, and their insecticidal activity are given in Tables 1, 2, 3.
Conclusions
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The strongest insecticidal action is possessed by preparation No. 115, containing 47.8% carbon; 5.7% hydrogen; 5.5–5.8% sulfur; 5.2–5.3% phosphorus; 2.13% nitrogen.
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The preparation was obtained under the following optimal conditions: amount of starting substances per 100 g of nitrolignin — 40 g of caustic soda, 700 ml of water, 12.6 ml of pyridine, 136.8 g of diethyl chlorothiophosphate; synthesis conditions — time 2 hours, temperature 92–95°C.
Table 1
| Preparation No. | Amount of starting materials, g: nitrolignin | Amount of starting materials, g: diethyl chlorothiophosphate | Analysis data for reaction products, %: phosphorus | Analysis data for reaction products, %: sulfur | Insecticidal activity (100% mortality of houseflies after min.) |
|---|---|---|---|---|---|
| 75 | 10,0 | 7,4 | 2,75 | 2,99 | 80 |
| 83 | 10,0 | 5,0 | 2,0 | 2,1 | 75 |
| 84 | 7,7 | 10,0 | 7,2 | 7,5 | 30 |
| 84/2 | 7,7 | 10,0 | 7,2 | 7,5 | 30 |
| 109 | 50,0 | 64,8 | 5,2 | 5,6 | 15 |
| 110 | 50,0 | 70,0 | — | — | 23 |
| 111 | 50,0 | 75,0 | — | — | 25 |
Note: time — 2 h, temperature — 92–95°C.
Table 2
| Preparation No. | Amount of starting materials, g: nitrolignin | Amount of starting materials, g: diethyl chlorothiophosphate | Synthesis conditions: t° | Synthesis conditions: time | Analysis data for reaction products, %: phosphorus | Analysis data for reaction products, %: sulfur | Insecticidal activity (100% mortality of houseflies after min.) |
|---|---|---|---|---|---|---|---|
| 87 | 7,7 | 10,0 | 18–20° | 5 min. | 0 | 0 | Inactive |
| 76 | 7,7 | 10,0 | 50–60° | 50 min. | 3,9 | 3,2 | 60 |
| 114 | 50,0 | 68,4 | 12–20° | 2 h | — | — | 27 |
| 115 | 50,0 | 68,4 | 92–95° | 2 " | 5,23 | 5,8 | 10 |
| 113 | 50,0 | 68,4 | 92–95° | 2 " | 5,00 | 5,2 | 20 |
| 109 | 50,0 | 68,4 | 92–95° | 2 " | 5,2 | 5,6 | 15 |
Table 3
| Preparation No. | Amount of starting materials, g: nitrolignin | Amount of starting materials, g: pyridine, ml | Amount of starting materials, g: caustic soda | Amount of starting materials, g: diethyl chlorothiophosphate | Amount of starting materials, g: water, ml | Analysis data for reaction products, %: phosphorus | Analysis data for reaction products, %: sulfur | Insecticidal activity (100% mortality of houseflies after min.) |
|---|---|---|---|---|---|---|---|---|
| 84 | 7,7 | 1,0 | 3,75 | 10,0 | 100,0 | 7,2 | 7,5 | 30 |
| 69 | 7,7 | 1,0 | — | 10,0 | 100,0 | — | 3,8 | 180 |
| 77a | 7,7 | — | 3,75 | 10,0 | 100,0 | — | 3,15 | 50 |
| 109 | 50,0 | 6,3 | 20,0 | 64,8 | 350,0 | 5,2 | 5,6 | 15 |
| 112 | 50,0 | — | 20,0 | 64,8 | 350,0 | — | 3,2 | 60 |
Note: time — 2 h, temperature — 92–95°C.
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