US2597534A

US2597534A - Neutral esters of thiolphosphoric acid

Info

Publication number: US2597534A
Application number: US184335A
Authority: US
Inventors: Schrader Gerhard
Original assignee: Bayer AG
Current assignee: Bayer AG
Priority date: 1949-05-07
Filing date: 1950-09-11
Publication date: 1952-05-20
Anticipated expiration: 1969-05-20

Description

Patented May 20, 1952 UNITED STATES PATENT OFFICE NEUTRAL ESTERS- g! THIOLPHOSPHORIC A D Gerhard Schrader, Opladen-Bruchhausen, Germany, assignor to Farbenfabriken Bayer, Leverkusen, Germany No Drawing. Application September 11, 1950, Serial No. 184,335. In Germany May 7, 1949 1 The present invention relates to the manufacture of neutral esters of thiolphosphoric acid,

and to new esters of this series.

Hitherto the neutral esters of thiolphosphoric acid of the formula:

alkyl. 0 0

alkyl. 0 S alkyl in particular the esters in which alkyl of the above formula is methyl, ethyl, propyl and isobutyl, were prepared by reacting salts of thiolphosphoric acid of the formula:

alkyl. 0 O

alk.0\ %O alkali NCS.alkyl alk.0\ O

The reaction is most conveniently carried out in an inert solvent, e. g. in benzene or its homologues, chlorobenzene and also in ketones such as acetone, methyl ethyl ketone, methyl propyl ketone, and others. Slight heating, as a rule to about 40 to 60 0., is required. The alkyl radicals of the alkyl thiocyanates employed may belong to the lower or higher alkyls such as methyl, ethyl, propyl, butyl, hexyl, dodecyl. Also alkyl thiocyanates containing the SON- group twice may be used in which case the reaction shown in the above equation will take place with two molecules of the alkali salts of dialkyl phosphites. Besides alkyl thiocyanates, also aralkyl thiocyanates may be used.

These neutral aliphatic esters of thiolphosphoric acid are, as a rule, oily liquids of a high i 4 Claims. (Cl. 260-461) 2 boiling point, and are distinguished by insecticidal properties.

It has further been found that neutral esters of thiolphosphoric acid of particular value and interest are obtained when in the above described new process instead of simple alkyl thiocyanates thiocyanates of the formula R. S. alk. SCN are used. R in this formula means alkyl, preferably methyl or ethyl, or aryl, in particular phenyl or substituted phenyl. The radical designated alk in this formula stands for a straight or branched alkylene chain. Compounds obtained by means of these thiocyanates correspond to the general formula:

in which R1 and R2 are alkyl radicals which may be the same or different, and are preferably lower radicals such as methyl, ethyl, or propyl. These new esters of thiolphosphoric acid are distinguished by very good insecticidal properties, in particular by their systemic insecticidal properties.

It has further been found that these valuable compounds can also be prepared by reacting alkali dialkyl thiophosphates with mercapto alkyl halides of the formula R. S. alk. hal. The alkali dialkyl thiophosphates react, as is known, e. g. from Journal of American Chemical Society 6'7 [1945], pp. 1662-1664 (T. W. Mastin, G. R. Norman and E. A. Weilmuenster) in their tautomeric form 2:

O.alkali Rlo 1 2 The reaction takes place according to the following equation:

R 0 Salkali R O\ O R 0 B.a1kali hel.alk.S.R

R 0 S.alk.S.R alkali halide It is carried out in the presence of inert solvents of the kind mentioned above at elevated temperatures, usually at about 40 to about 0.

Another new process of preparing these com pounds consists in reacting dialkyl phosphoric chlorides with alkali salts of mercapto alkyl mer- 3 captans of the formula R. S. alk. SH. The reaction takes place according to the following equation:

Also here the reaction is carried through in the presence of an inert solvent ofxthe mentioned kind at elevated temperatures, usually at about 40 to about 100 C.

Neutral aliphatic esters of. thiophosphoricaeid substituted in one ester group by the. radical of an aliphatic or aromatic mercaptan obtainable by one of the forementioned processes are e. g.:

0,0-diethyl s-fi-ethylmercapto' ethyl thiolphosphate 0,0-diethyl S-B-methylmercapto=ethyl thiollzphosphate 0,Q-.diethy1 S- 3A-methylphenylmercaptoeethyl thiolphosphate O,O -die.thyl S-ethylmercapto-methylthiolphos- *phate 0,0-ediethylz SHiemethylphenyImercaptoemethyl :thiolphosphate 0,0-di-1isopropyl s-p ethylmercapto-ethyli;tliio1- lxphosphate The present invention is illustrated btfithefollowing examples; it is, however, not restricted thereto:

Example 1 70 grams of diethyl phosphite are mixedwith 2 cc; of absolute alcoholand diluted with 100 cc. of toluene: 12 grams of sodium are caused to act uporr the solution thus "obtained: When the sodium has dissolved, 37 grams of methyl thiocyanate are added dropby drop with stirring at 40 Cb Stirring is-continued at40 C. for 2 hours.

15 cc. of water are then added to the reaction mixture and r the precipitated salts are removed by filtering." 48 grams of 0,0-dimethyl S-nethyl thiolphosphatehaving -a-boiling pointof 112-113" C: at 14==mm.' pressure are obtained. The *prod not is soluble in-Water.

Example 2 "Sodium salt prepared from 12' grams of sodium and 70 grams of diethyl phosphite in benzene as described in Example 1 is heated to 45-50" C. with stirring. At'this temperature'l grams of ethyl thiocyanate are added drop, by drop Within 10 minutes" controlling the temperature by cooling. The reaction mixture is then heated to 55 C. ior-::one;hour.c.After-workingup as usual grams of 0,0-diethyl S-ethyl thiolpho'sphate, boiling at 98 C. at 2 mm. pressure, are obtained. The new product is soluble in water to a limited degree.

Example 3 52 grams of n-propyl thiocyanate are reacted at 40 C. with the sodium salt prepared from 12 grams of sodium-and '70 grams of diethyl phosphiteinzbenzene as described in Example 1. The reactionmixturesobtained is heated to 55 C. for one hour andthen worked up' as usual. 40 grams of OD-diethyl S1-propyl thiolphosphate, boiling at.103-1053.C. at .1- mm. pressure, are obtained. Theproduct isinsoluble in. water.

phite as described in Example 1.

4 Example 4 57.5 grams of isobutyl thiocyanate are reacted at 40 C. with the sodium salt prepared from 12 grams of sodium and 70 grams of diethyl phosphite as described in Example 1. The reaction mixture. thus obtained is heated to 55 C. for one hour and subsequently worked up as usual. 74 grams of 0,0'-diethy1 S-isobutyl thiolphosphate, boiling at 105 C. at .5 mm. pressure, are obtainedJi'iThe product is insoluble in water.

Ezcample 5 65 gramsof n-hexy'l thiocyanate are reacted at 40? C..with thesodium salt prepared from 12 grams of sodium and 70 grams of diethyl phos- The reaction mixture is heated to' 55-60 C. for one hour and Worked up as usual. 48 grams of 0,0-diethyl S-hexyl thiolphosphate of the boiling point C. at .1 mm. pressure are obtained.

- Example 6 115 grams of dodeoyl thiocyanate are reacted at-50 C; with the-sodium salt preparedfrom 12 grams of sodium and '70 grams of diethyl phosphite as described in'Example 1. The reaction mixture is heated to 5560 C. for one hour and is then worked up as usual. 60 grams of 0,0-diethyl S-dodecyl thiolphosphate, having a boiling point of 185-190" C. at. .5: mm. pressure; are obtained.

Emample 7 The sodium salt prepared from 12 grams of 'sodium and '70 grams of diethyl phosphite as described in Example 1 is heated to 45 C. At this temperature 76 grams ofbenzyl thiocyanate are added drop by drop with stirring. The reaction mixture' is-further heated to 40 C. for halfan hour and is then-workedup asusual. 70'grams of 0,0-diethyl S-benzyl thiolphosphate with a boiling point of 165-17 0 C. at 2 'mm.'pres sure are obtained.

Example 8 Example 9 [grams of sodium are suspendedin' ,cc. of toluene. I 42. grams of diethyl phosphite are added and the mixture isstirred at'40 50 C., until'allsodium is. dissolved. With stirring 44 grams of ,9 ethylmercapto ethyl thiocyanate (boiling at 90 C. at 1mm. pressure) are added drop bydrop at a temperature of 40 C. The.

mixture is kept for one .hour at' 50 C. and is then worked up. in the usual manner. .Thus 28 gramsof '(C2H5O)2PO.S.C2H4.S.CzI-I5 boiling at 137-141 C.'at 1.mm. pressure are obtained.

The product is alight-yellow oil which is insoluble in water.

Example 1 0 '40 grams of B-methylmercapto-ethyl thiocyanate are added drop by drop with stirring art-40 C. to the sodium salt solution obtained according to Example 9. The temperature is kept for one hour at 50 C. and is then worked up in the usual manner. Thus 34 grams of boiling at l34138 C. at 2 mm. pressure ar obtained. 1

Example 11 63 grams of fl-mercapto-ethyl ethyl sulfide CzH5.S.C2H4.SI-I (described in Annalen der Chemie 240, p. 311) are added to 12 grams of finely dispersed sodium in 1'70 cc. of toluene drop'by drop, while stirring. The temperature is raised to 60 C. and then kept for half an hour. The sodium will then be dissolved. Thereafter the finely dispersed sodium salt of the mercaptan is cooled to C. Thereto under constant outside cooling 8? grams of diethyl phosphoric monochloride, dissolved in 100 cc. of toluene, are added drop by drop within 20 minutes, while stirring. After adding the chloride the reaction product is kept at room temperature for a further hour. By adding 20 cc. of water the salts are then turned into a filterable form. After distilling oil the toluene the remaining oil distils at a boiling point of 136 C. under 1 mm. pressure. 93 grams of 0,0-diethyl S-p-ethylmercapto-ethyl thiolphosphate, a slightly yellow oil, insoluble in water are obtained. Yield: 72 per cent of theory.

In a similar way can be obtained:

CgHsO O PS.CH,.OH.S.CH:

boiling at 135 C. under 2 mm. pressure not distillable Example 12 '7 grams of finely pulverized sodium are suspended in 100 cc. of toluene. 43 grams of diethyl phosphite are added thereto at a temperature of 40 C. The temperature of 40 C. is kept for half an hour. Then the sodium will be dissolved. Thereafter, 10 grams of sulfur are added to the reaction product at a temperature of 60 and it is then heated for another hour to 105 C. The sodium diethyl thiophosphate being now finely dispersed is reacted with 34 grams of chloromethyl ethyl sulfide C2H5.S.CH2.C1 (cf. Berichte der Deutschen Chemischen Gesellschaft 69 [1936], p. 1612) at a temperature of 55 C. The temperature of the reaction mixture is kept for another hour at 55 C., then 8 cc. of water are added, the toluene layer is removed and fractionated. 40 grams of 0,0-diethyl S-ethyllrnercapto-methyl thiolphosphate of a boiling point of 129-130" C. at 1.5 mm. pressure are obtained. The yield corresponds to 60 per cent of theory. The new thiolester is insoluble in water.

Example 13 Sodium diethyl thiophosphate finely dispersed is prepared from the same quantities as in Example 1. 52 grams of chloromethyl 4-methylphenyl sulfide CH3.C6H4.S.CH2.C1 (cf. Berichte der Deutschen Chemischen Gesellschaft 69 [1936], p. 16 12) are added to this suspension. The reaction mixture is heated for 4 hours to 105 C.; the formed salts are then brought into a filterable form by adding 10 cc. of water, the toluene layer is separated and fractionated. 60 grams of 0,0 diethyl S-4-methylphenylmercapto-methyl thiolphosphate with a boiling point of 178 C. under .5 mm. pressure are obtained, corresponding to a yield of 65 per cent. The new substance is a colorless oil insoluble in water.

Example, 1 4

Sodium diethyl thiophosphate is prepared from the same quantities as in Example 1. To this salt 37 grams of B- chloroethyl ethyl sulfide C2H5.S.C2H4.Cl (cf. Annalen der Chemie 240 [1887], p. 310) are added at'a temperature of 70 C., while stirring; The reaction mixture is then heated for another two hours to C., and the salts are removed by means of water as in the preceding examples. By fractionating the toluene layer 54 grams of 0,0-diethy1 S-flethylmercapto-ethyl thiolphosphate are obtained, corresponding to a yield of 70 per cent; colorless oil insoluble in water having a boiling point of 136 C. under 1 mm. pressure.

In a similar way e. g. the following compound can be produced:

C H O boiling at 134 0. under 2 mm. pressure Example 15 7 grams of sodium :powder are suspended in 100 cc. of toluene and heated with 42 grams of diisopropyl phosphite to 50 C., until the sodium is dissolved. Thereafter 9 grams of sulfur are added and the mixture is heated for another hour to 90-95 C. It is then cooled to 50 C., and at this temperature 37 grams of p-chloroethyl ethyl sulfide are added drop by drop. The reaction mixture is kept for further 4 hours at 90-95 C., while stirring. By adding 5 cc. of water the salts formed are thereupon brought into a filterable form. After sucking oil the salts the solvent is removed from the toluene solution. The remaining crude product is now kept for 10 minutes at an inside temperature of C. under a vacuum of 2 mm. to remove the last traces of the volatile solvent. 0,0-di-isopropyl S-B-ethylmercaptoethyl thiolphosphate thus obtained is a brownyellow oil insoluble in water (60 grams). At a pressure of 2 mm. the ester can only be distilled with strong decomposition.

Example 16 Young peach trees infested with peach-aphides are sprayed with an aqueous solution containing 0.005 per cent of the following compound:

P-S. CH CH,.S.CH;

After some hours all aphides are killed.

This aqueous solution may also be used in the presence of alkaline reacting agents for simultaneously combating fungi.

Example 17 Tale is ground with the following substance:

PS.CH2.0H1.S.C2H5

so-that a 5wpen=centidust iszobtained: :Thiss'dust is applied to. "branches with -caterpi1lars(Malacosomw-neustria) r'l'he fcaterpillarsware killed after a short-time.

This ,:applicationis a-seontinuationein-part or" myoopending :,.ear1ier;application:Serial' N0'.--94,- 721-; filed May 21,11949.

I claim:

1. As new compounds neutral esters of thiolphosphoric acid of thegeneral'formula:

whereinaeRi and R2 stand: for lower Lalkyl radi cals, e alk' stands for a lower: alky'leneichain', and R stands for one of the group consistingof lower alkyl radicals, phenyl radicals and lower alkyl substituted" phenyl radicals.

2.- As-new compounds neutral: esters of 'thiol phosphoric acid of the-general formula:

Rio

6- wherein R, ..-Rr:- and Rzstandior. lower alkyl radicals, and X is one of the integers 1 and 2. 3% As new-compound the-neutral ester of thiolphosphoric acid of the formula:

C|H|O O 0,330 SR'JHiLCHjISDaHt 4;. Aszneweompoundthe neutral ester oilthiolphosphorioacid' of. the formula:

SQC Hi CIhS. CHI

GERHARD SCHRADER.

- No references cited.

Claims

1. AS NEW COMPOUNDS NEUTRAL ESTERS OF THIOLPHOSPHORIC ACID OF THE GENERAL FORMULA: