PREPARATION OF O-METHYL-O-ETHYL-O-NITROLIGNOTHIOPHOSPHATE FROM NITROLIGNINS OF COTTONSEED HULLS

L. A. PERSHINA, A. I. GALOCHKIN, V. P. ZHUCHKOV, Zh. V. SHLOMCHAK

(Presented by the scientific seminar of the Faculty of Chemical Technology)

The lignins of cotton plants differ from the lignins of woody species both in elemental composition and in functional groups. In terms of the content of methoxyl groups, cotton-plant lignins occupy an intermediate position between the lignins of coniferous and deciduous species.

There are 1.28–1.36 acetylatable hydroxyls for each structural unit $C_9$ of cotton-plant lignin, whereas in spruce lignin there are 1.15 and in beech lignin 1.23.

The molecular weight of cotton-plant lignins is considerably lower than the molecular weight of lignin isolated from spruce wood by an analogous method. The molecular weight of wood lignin is 11000; that of cotton-plant boll lignin is 3600–3700; that of stem lignin is 4200–4300 [1].

Hydrolysis lignin of cottonseed hulls from the Andizhan plant contains more carboxyl and methoxyl groups than hydrolysis lignin of woody species; the amount of hydroxyl groups is almost the same.

From hydrolysis lignin of cottonseed hulls, nitrolignin has been obtained at the Institute of Organic Chemistry of the Academy of Sciences of the USSR [2]; at present it is produced by the Andizhan hydrolysis plant as a commercial product.

We have obtained from nitrolignin of woody species an insecticide of the thiophos type [3, 4].

The present work shows that nitrolignin from the Andizhan hydrolysis plant can serve as a raw material for preparing organophosphorus insecticides.

The optimum conditions for preparing O-methyl-O-ethyl-O-nitrolignothiophosphate were investigated.

The quality criteria for the insecticides were the sulfur content, insecticidal activity, and yield.

The insecticidal activity of the preparations was determined on houseflies (Musca domestica L.), which were placed, 20 at a time, in a 200 ml conical flask containing the preparation at the rate of 1 g per 1 m².

Experimental Part

Starting reagents. O-methyl-O-ethylchlorothiophosphate was obtained from the Shchelkovo Chemical Plant. The technical product was purified by repeated distillation under vacuum.

O-Methyl-O-ethyl chlorothiophosphate, b.p. 96–102°C (26–27 mm Hg), contains 17% sulfur and 17.9% chlorine.

The Andizhan Hydrolysis Plant supplied us with five samples of nitrolignins obtained under different conditions.

Sample No. 1—nitrolignin obtained from mixed lignin under the “normal oxidation regime”: nitric acid content in the working solution—12%; sulfuric acid content—2.0–2.2%; T:L module = 1:4; reaction temperature—52–54°C; time—6 h.

Sample No. 2—nitrolignin obtained from mixed lignin under “severe oxidation conditions”: nitric acid content in the working solution—14–15%; sulfuric acid content—2.2–2.5%; T:L module = 1:15; reaction temperature—54–56°C; time—6 h.

Sample No. 3—nitrolignin obtained by the action of 9.5–10% nitric acid on mixed lignin.

Sample No. 4—nitrolignin obtained by the action of 11–11.5% nitric acid on mixed lignin.

Sample No. 5—nitrolignin obtained by nitration with 12–12.5% nitric acid.

Sample No. 6—nitrolignin obtained by us by the action of 12% nitric acid and 2% sulfuric acid on lignin from pentose–hexose cooks, at a T:L module = 1:14, reaction temperature 52–54°C, time—6 h.

In all nitrolignin samples, hydroxyl, carboxyl, and methoxyl groups, total nitrogen by the Dumas method, and nitrate nitrogen by Schulze–Tiemann were determined.

The analytical data are given in Table 1.

Interaction of nitrolignin of the “normal oxidation regime” with O-methyl-O-ethyl chlorothiophosphate

Nitrolignin, alkali, a definite amount of water, and pyridine were charged into a three-necked flask equipped with a stirrer and a reflux condenser. With the stirrer operating, the flask was heated in a water bath for 3–5 min; then O-methyl-O-ethyl chlorothiophosphate was added. After a definite time the bath was removed, 5 ml of HCl ($d = 1.19$) was added to the reaction flask, after which the stirrer was switched on for 5 min, and then the reaction mass was poured into a beaker with 100 ml of water and allowed to stand for 30 min. The precipitate was filtered off and washed with water until a negative reaction for Cl′.

The influence on the insecticidal properties and sulfur content of the reaction products of temperature (Table 2) and reaction time (Table 3), the amounts of O-methyl-O-ethyl chlorothiophosphate and pyridine (Table 4), and of caustic soda and water (Table 5) was studied.

Table 1

Table 2

Table 3

Table 4

Note: time — 1 hour, temperature — 60°C.

Table 5

Note: time—1 h, temperature—60°C.

Reaction of nitrolignin of the “severe oxidation regime” with O-methyl O-ethyl chlorothiophosphate

The effect on the insecticidal properties of the reaction products and on their sulfur content of the temperature and reaction time, and of the amount of O-methyl O-ethyl chlorothiophosphate, was investigated (Tables 6 and 7).

Reaction of nitrolignin from pentose-hexose cooks with O-methyl O-ethyl chlorothiophosphate

From nitrolignin obtained by us by nitration of hydrolytic lignin from pentose-hexose cooks and O-methyl O-ethyl chlorothiophosphate, a series of preparations with insecticidal action was synthesized. The influence of the amounts of O-methyl O-ethyl chlorothiophosphate and alkali on the insecticidal properties and sulfur content of the reaction products was investigated (Table 8). The syntheses were per-

Table 6

Note: amount of nitrolignin—10 g, MEKhTP—11 ml, water—70 ml, pyridine—1,2 ml, caustic soda—7 g.

Table 7

Note: reaction temperature—60–65°C; time—1 h.

Table 8

were introduced according to the above-described procedure at a temperature of 60°, time—1 h.

Discussion of Results

On the basis of the data in Tables 2, 3, 4, 5, 6, 7, and 8, it follows that the optimum conditions for obtaining O-methyl-O-ethyl-O-nitrolignothiophosphate are almost the same for the different nitrolignin samples. This can be explained by the almost identical functional composition of the nitrolignins (Table 1).

For obtaining O-methyl-O-ethyl-O-nitrolignothiophosphate, nitrolignin with the following characteristics is suitable:

hydroxyl groups . . . . 5.9–6.3%
methoxyl groups . . . . 1–2%
carboxyl groups . . . . 10–12%
total nitrogen . . . . 4–4.5%

With the highest sulfur content, and consequently with a strong insecticidal action, O-methyl-O-ethyl-O-nitrolignothiophosphate is obtained under the following conditions.

The working ratio (nitrolignin : water) was taken by us as 1 : 7, since with this amount of water the reaction mass is mixed well. Throughout the synthesis the medium of the reaction mass must be alkaline, and only at the end—slightly acidic. The optimum reaction temperature is 60°C, and the time is 1 hour.

For 10 g of nitrolignin, 10 ml of O-methyl-O-ethyl chlorothiophosphate, 1.2 ml of pyridine, 70 ml of water, and 4 g of caustic soda are used.

O-methyl-O-ethyl-O-nitrolignothiophosphate from cottonseed-hull nitrolignin is a dark-brown powder with an unpleasant odor. It is insoluble in water and organic solvents. It is readily soluble in soda and alkali.

Elementary composition:

O-methyl-O-ethyl chlorothiophosphate, stored for a year in a dark bottle with a ground-glass stopper at room temperature, retained its original activity.

In insecticidal activity the preparation is almost not inferior to thiophos. The toxic dose causing the death of 50% of mice upon intraperitoneal administration is 100 mg per kilogram of animal body weight.

LITERATURE

1. N. N. Shorygina, Kh. R. Niyazov. Study of lignins isolated from cotton plant by the method of mechanical grinding. Izv. AN SSSR, Otd. khim. nauk, No. 6, 1962.

2. T. V. Izumrudova, N. N. Shorygina, I. B. Adel, O. S. Zagor-
   mistr, Z. T. Salomatina. Prospects for the use of hydrolysis lignin in the petroleum industry. Zh. Gidroliznaya i lesokhimicheskaya promyshlennost, No. 1, 1961.

3. L. A. Pershina, S. N. Zagrebelnyi. Interaction of diethyl chlorothiophosphate with hydrolysis lignin and its derivatives. Izv. TPI, vol. 111, 1961.

4. B. V. Tronov, L. A. Pershina, A. V. Kovalenok. Influence of the optimum conditions for the synthesis of O,O-diethyl-O-nitrolignothiophosphate. Izv. TPI, vol. 136, 1965.