US2409329A - Organic thiocyano compounds - Google Patents

Description

Patented Oct. 15, 1946 UNITED STATES PATENT OFFIC Shell Development Company,

San Francisco,

Calif., a corporation of Delaware No Drawing. Application February 28, 1944,

' Serial N 0. 524,309

9 Claims. (Cl. 260-454) n 1 l n This invention relates to organic thiocyano compounds, and more particularly pertains to compounds of the general formula I R-OCX wherein is an alkyl-substit uted cyclohexyl radical containing at least two alkyl groups, and X is a thiocyano-substituted hydrocarbon radical.

The. organic thiocyano compounds of the invention have many importantluses. 'Theymay, for example, be used as wetting agents,.as plasticizers, as addition. agents for rubber, and .as intermediates in the synthesis of other valuable organic compounds. They are particularly user ful, as insecticides, fungicides and parasiticides since, in addition to possessing unusually high insecticidal activity, they havev an inoifensive odor, are light-stable, arecompatible with or soluble in light paraflinic mineral oils such as kerosene, and are not damaging in any way to fabrics, wall paper, painted walls, etc. This use of the compounds of the invention as insecticides, fungicides and parasiticides is described and claimed in the copending application, Serial Number 482,032, filed April 6, 1943, of which this applicationisacontinuation-impart. 1 s

Theorganic thiocyano compounds or the invention have the general formula r Ib-O-PJ-X wherein R is an alkyl-substituted cyclohexyl radical which is substituted with at least two alkyl groups, and X is a thiocyano-substituted hydrocarbon radical.

Suitable alkyl group substituents on the cyclohexyl radical are, for example, the methyl, ethyl, propyl, butyl, amyl, hexyl, heptyl, octyl, nonyl, etc., radicals and theirhomologues; aswell as certain unsaturated radicals such as the allyl, methallyl, crotyl, etc.,.radica1s. The said groups may be substituted in any desired position on the cyclohexyl radical, although the third and fifth carbon atoms relative to the carbon atom bearing the bond to the oxygen atom represent preferred positions. In these preferred compounds the car...

bon atomsof the cyclohexyl nucleu maybe linked to the alkyl groups in any possible manner of distribution, i. e., one alkyl group on each of the carbon atoms, in the 3 and 5 positions, one alkyl group on one of the indicatedcarbon atoms and two on the other, ortwo alkyl groups on either or both of the indicated carbon atoms. Although the" sizeof the alkyl group is 'notof critical importance, those compounds are preferred wherein the alkyl groups contain less than five carbon atoms, especially those wherein all of the alkyl groups are methyl groups. Especially desirable are those compounds in whichthere are two methyl groups on the cyclohexyl radical, one

substituted in the 3 position and the other in the 5 position, and those wherethere are three substituent methyl groups, especially those where there are two methyl groups in the 3 position and one in the 5 position. Thus 3,5-dimethylcyclohexyl thiocyanoacetate,

oH-om 0 on; OH-O -CHaSON CHCHz a and 3,3,5-trimethylcyclohexyl thiocyanoacetate,

Oil-CH: CH: on-o-c'L-ora-sosr oom on; on,

stituted cyclohexyl esters of the mono di-, or

poly-thiocyano substituted saturated or unsaturated aliphatic acids. The aliphatic acid residue may be of any desired-molecula weight, depending upon the use to which the ester is to be put. The alkylcyclohexyl esters of the lower thiocyano aliphatic acids having from 2 to 6 carbon atoms may, for example, be particularly effective foruse as insecticidal toxicants while the cyclohexyl esters of the higher acids, i. e. those having up to about 20 carbon atoms, may be more suitable for use as wetting agents.

Representative acids, which may be used in forming the desired thiocyano esters include the C2 to C20 straight chain and branched chain saturated and unsaturated aliphatic acids such as acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, capric acid, undecylic acid, undecylenic acid, lauric acid, myristic acid, palmitic acid, oleic acid, stearic acid, arachidic acid, and their homolo-gues and analogues together with suitably substituted compounds thereof, such as hydroxyacetic acid, lactic acid, dehydro-xy-nbutyric acid, d-hydroxyisovaleric acid, ricinoleic acid, etc.

The compounds of the invention may be prepared in a variety of ways. They may be prepared, for example, by reacting metal thiocyanates with the sulfated esters of the appropriate alcohols. However, a preferred method of preparation generally comprises reacting an alkyl substituted cyclohexanol, e. g. 3,3,5-trimethyl cyclohexanol (dihydroisophorol) in the presence of an esterification catalyst, if desired, with a suit able halo-gen substituted acylating agent, and reacting the ester so produced with a suitable metal thiocyanate to obtain the desired thiocyano ester. These reactions may be represented by the following equations wherein R=an alkyl substituted cyclohexyl radical containing at least two alkyl groups:

0 ROH memo-0H ClCHzC-OR H no-oorncl NHASCN A ROCCHZSCN NHlOl As indicated, it may be desirable when effecting the esterification of an alkyl substituted cyclohexanol with an acylating agent, e. g. a halogen substituted aliphatic carboxylic acid, to make use of an esterification catalyst to accelerate thereaction. Almost any of the esterification catalysts known to the art may be used for this purpose. Suitable catalysts include, for example, the mineral acids such as sulfuric acid or phosphoric acid. Para-toluene sulfonic acid represents a preferred catalyst, since it exerts the desired catalytic action without producing any substantial charring of the constituents of the reaction mixture. The catalysts are active in small amounts, an amount of catalyst which is equal to but about 1% by weight of the alcohol used being a suificient amount in most cases.

Either step or stage of the above-described preferred method for preparing the presently disclosed thiocyano esters may be carried out in the presence of an inert solvent, such as methanol, ethanol, isopropanol, butanol, isobutanol, acetone, ethyl acetate, benzene, toluene, xylene, hexanes, octanes, isopropyl ether, hydrocarbon fractions, such as gasoline, etc. It is usually preferred to carry out the second step, i. e. the conversion of the chloro ester to the thiocyano ester, in an alcoholic medium. Each step may be carried out at any temperature within the range of between about 0 C. and about 250 C., and preferably in the range of between about 50 C. and about 150 C. It may be desirable to carry out the reactions of either step in the absence of oxygen, as, for example, in an atmosphere of carbon dioxide. The products of each stage are preferably vacuum distilled, although if only a crude product is desired, no distillation is needed.

Suitable halogen substituted acylating agents include the halogen substituted aliphatic carboxylic acids, e. g. the chloro-, bromoor iodosubstituted aliphatic carboxylic acids, including monochloroacetic acid, dichloroacetic acid, trichloroacetic acid, alpha-chloropropionic acid, beta-chloropropionic acid, the dichloropropionic acids, the dichlorobutyric acids, the chloroisovaleric acids, the chlorolauric acids, the chloromyristic acids, the chlorostearic acids, the chloroleic acids, the chlororicinoleic acids, the chloromalonic acids and the corresponding bromoor iodo-substituted acids. Mixtures may be utilized if desired, as may the anhydrides of the halogen substituted carboxylic acids, or the acyl halides of these halogen substituted carboxylic acids.

Suitable metal thiocyanates for use in the synthesis include those which are of a sufiiciently reactive nature to undergo reaction with a halogen substituted aliphatic acid. It is also desirable that the metal thiocyanates be relatively soluble in the reaction medium. In general, ammonium thiocyanate, the thiocyanates of the alkali metals, and the thiocyanates of the alkaline earth metals represent suitable reagents for use in effecting the conversion of the halogen substituted esters to the thiocyano substituted esters. Ammonium thiocyanate, sodium thiocyanate, potassium thiocyanate, are preferred members of this group.

As examples of preferred methods of forming the desired compounds of the present invention the following may be given:

In a, 250 ml. flask equipped with a, refiux condenser was placed 142 g. (1.0 mol) of 3,3,5-trimethylcyclohexanol (dihydroisophorol) and while maintaining the temperature of the reaction mixture at C., 124 g. (1.1 mols) of chloroacetyl chloride was added dropwise. After reaction had ceased, the mixture was cooled and washed with water and 5% aqueous sodium carbonate and then distilled. 3,3,5-trimethylcyclohexyl chloroacetate, having a. boiling point of 109 C. to 110 C. at 5 mm. pressure and by analysis a 16.25% chlorine content (16.25% theoretical chlorine content) was obtained. Into a one liter flask was placed 164 g. (0.75 mol) of the resultant 3,3,5-trimethylcyclohexyl chloroacetate, '76 g. (1.0 mol) of ammonium thiocyanate, and 400 cc. of ethanol (95%). The mixture was refluxed for about one hour and then the ammonium chloride formed was filtered off. The ethanol was removed by distillation and the remaining material was distilled through a Claisen flask at reduced pressure to obtain 3,3,5-trimethylcyclohexyl thiocyanoacetate having a boiling point of 134 C. to 138 C. at ca. 3 mm. pressure, which material gave on analysis a sulfur content of 13.27% (13.1% sulfur-theoretical for C12H19O2SN).

In another .case the 3,3,5-trimethylcyclohexanol was first separated into its cis and trans forms. One isomer had a boiling point of 108.1 C. to 108.4" C. at 50 mm. pressure, and the other isomer had a boiling point of 117.2 C. to 118.0 C. at 50 mm. pressure. Since the evidence is not conclusive as to which is the cis and which is the trans form, these forms are herein referred to as the low boiling and the high boiling types. The thiocyanoacetates of both of these isomers were prepared as in the above example. The isomer of 3,3,5-trimethylcyclohexyl thiocyanoacetate prepared from the low boiling product had a boiling point of 134 C. to 142 C. at 3 mm. pressure and a sulfur content by analysis of 13.6% (13.27% su1furtheoretical) and the 3,3,5- trimethylcyclohexyl thiocyanoacetate isomer prepared from the high boiling form had a boiling point of C. to 131 C. at 3 mm. pressure and a sulfur content by analysis of 13.6%.

In a like manner 3,3,5 -trimethylcyclohexyl thiocyanoacetate was prepared from a mixture of the cis and trans forms of 3,3,atrimethylcyclohexanol by reacting the latter with chloroaceticacid in the presence of toluene as an entraining agent for water and then reacting the resulting product with ammonium thiocyanate. This product had a boiling point of 137.5 C. at 3.0 mm. pressure and a sulfur content by analysis of 13.5%.

In a similar manner 3,3,5-trimethylcyclohexyl alpha-thiocyano propionate was prepared by esterifying 3,3,5-trimethylcyclohexanol with alpha-chloropropionic acid and reacting the product thus obtained with ammonium thiocyanate. The 3,3,5-trimethylcyclohexyl alpha-thiocyano propionate product had a boiling point of 149 C. to 151 C. at 4.7 mm. and a sulfur content by analysis of 12.6% (12.55%-theoretical).

Similarly, 3,5-dimethyl cyclohexyl thiocyano acetate was prepared by heating 3,5-dimethylcyclohexanol with a 10% molar excess of chloracetic acid, a small amount of an esterification catalyst comprising para-toluene sulfonlc acid and a sufiicient amount of benzene to serve as an entraining agent for the water formed during the course of the reaction. Distillation of the reaction product under subatmospheric pressure resulted in the isolation of a good yield of 3,5-dimethylcyclohexyl chloro acetate. The chloro acetate was then converted to the corresponding thiocyano acetate by reacting it with a 10% molar excess of ammonium thiocyanate in a solution of ethyl alcohol. After removal of the alcohol, the thiocyano acetate product was distilled. Its boiling point was 114 C. to 119 C./1 mm. It contained 13.8% sulfur (calculated for 3,5 dimethylcyclohexyl thiocyano acetate, 14.1%).

In a like manner are prepared: 3-methyl,5- ethyl-cyclohexyl thiocyanoacetate from 3- methyl,5 ethyl cyclohexanol and chloroacetic acid; 3-butyl,5-methyl-cyclohexyl thiocyanoacetate from 3-butyl,5-methyl-cyclohexanol and chloroacetic acid; 3-methyl,5-isopropyl-cycloheXyl alpha-thiocyano-oleate from 3-methyl,5- isopropyl-cyclohexanol and alpha-bromo oleic acid; 3-ethyl,5-propyl-cyclohexyl thiocyanopropionate from 3-ethyl,5-propyl-cyclohexanol and alpha-chloropropionic acid; 3propyl,5-pentylcyclohexyl thiocyanostearate from 3 -propyl,5- pentyl-cyclohexanol and alpha-chloro stearic acid; 3,5 diethyl cyclohexyl thiocyanoacetate from 3,5-diethyl-cyclohexanol and chloro acetic acid; 3,5-dimethyl-cyclohexyl dithiocyanoacetate from 3,5-dimethyl-cyclohexanol and dichloro acetic acid; 3,5-dipropyl-cyclohexyl thiocyanoacetate from 3,5 dipropyl cyclohexanol and bromo acetic acid; 3,5-dibutyl-cyclohexyl thiocyanoisobutyrate from 3,5-dibutyl-cyclohexanol and alpha-chloro isobutyric acid; 3,3-dimethyl, 5-ethyl-cyclohexy1 thiocyanoacetate from 3,3-dimethyl-5-ethyl-cyclohexanol and chloro acetic acid; 3,3-diethyl-5-propyl-cyclohexyl thiocyanopropionate from 3,3-diethyl-5-propyl-cyclohexanol and alpha-chloro propionic acid; 3-methyl- 5,5-dibutyl-cyclohexyl thiocyanovalerate from 3- methyl 5,5 dibutyl-cyclohexanol and alphabromo valeric acid; 3,3,5-tri-ethyl-cyclohexyl thiocyanoacetate from 3,3,5-triethyl-cyclohexanol and iodo acetic acid; 3,3,5-tributyl-cyc1ohexyl thiocyanoacetate from 3,3,5-tributyl-cyclohexanol and chloro acetic acid; 3,3,5-tripropylcyclohexyl beta-thiocyanopropionate from 3,3,5- tripropyl cyclohexanol and beta-chloro propionic clohexanol and chloro acetic acid; 3,3-dimethyl-" 5-ethyl-5 propyl cyclohexyl thiocyanoacetate from 3,3 dimethyl-5-ethyl-5-propyl-cyclohexanol and chloro acetic acid; 3-methyl-3-ethyl-5,5- dibutyl-cyclohexyl thiocyanoacetate from 3- methyl-3-ethyl 5,5 dibutyl-cyclohexanoland chloro acetic acid; 3-methyl-3-ethyl-5-propyl-5- butyl cyclohexyl thiocyanoacetate from 3 methyl-3-ethyl-5-propyl 5 butyl-cyclohexanol and chloro acetic acid; 3,3,5--trimethyl-5-ethylcyclohexyl thiocyanoacetate from 3,3,5 trimethyl-5-ethyl-cyclohexanol and chloro acetic acid; 3,3,5,5-tetramethyl-cyclohexyl thiocyanoacetate from 3,3,5,5-tetramethyl-cyclohexanol and chloro acetic acid; 3,3,5,5tetraethyl-cyclohexyl thiocyanoacetate from 3,3,5,5-tetraethylcyclohexanol and chloro acetic acid.

I claim as my invention:

1. 3,5-dimethylcyclohexyl thiocyanoacetate.

2. 3,3,5-trimethylcyclohexyl thiocyanoacetate.

3. The 3,3,5-trimethy1cyclohexy1 thiocyanopropionates.

4. An ester of a polyalkyl cyclohexanol and a thiocyano-substituted aliphatic carboxylic acid, which ester contains no more than three alkyl radicals directly linked to nuclear carbon atoms of the cyclohexyl radical, and wherein all of the alkyl radicals are directly linked to nuclear carbon atoms by means of primary carbon atoms, only one of the alkyl radicals being directly linked to the nuclear carbon atom in the 5 position relative to the acid radical, and the other alkyl radicals being directly linked to the nuclear carbon atom in the 3 position relative to the acid radical.

5. An ester of a trialkyl cyclohexanol and a thiocyano-substituted aliphatic carboxylic acid,

linked to nuclear carbon atoms of the cyclohexyl radical, one of the alkyl radicals being linked directly by means of a primary carbon atom to the 5 nuclear carbon atom in the 3 position with respect to the acid radical, and the other alkyl radical being linked by means of a primary carbon atom to the nuclear carbon atom in the 5 position with respect to the acid radical.

7. An ester of a polymethyl cyclohexanol and a. thiocyano-substituted aliphatic carboxylic acid, which ester contains no more than three alkyl radicals, all of which are methyl radicals, directly linked to nuclear carbon atoms of the cyclohexyl radical, only one of the methyl radicals being linked to the nuclear carbon atom in the 5 position relative to the acid radical, and the other methyl radicals being directly linked to the nuclear carbon atom in the 3 position relative to the acid radical.

8. An ester of a trimethyl cyclohexanol and a thiocyano-substituted aliphatic carboxylic acid, which ester contains only three radicals, all of which are methyl radicals, directly linked to nuclear carbon atoms of the cyclohexyl radical,

one of the methyl radicals being directly linked to the nuclear carbon atom in the 5 position with respect to the acid radical, and the other two methyl radicals being directly linked to the nuclear carbon atom in the 3 position with respect to the acid radical.

9. An ester of a dimethyl cyclohexanol and a thiocyano-substituted aliphatic carboxylic acid, which ester contains only two alkyl radicals, both of which are methyl radicals linked to nuclear carbon atoms of the oyclohexyl radical, one of the methyl radicals being directly linked to the nuclear carbon atom in the 3 position relative to the acid radical, and the other methyl radical being linked to the nuclear carbon atom in the5 position relative to the acid radical.

PAUL H. WILLIAMS.