the polymethylated muconic acid esters suitable for use in preparing the novel compositions disclosed herein are the c 1 to c 20 hydrocarbyl mono - and di - esters of the acids wherein the hydrocarbyl group may contain from 1 - 20 carbon atoms , as well as any mixtures thereof or mixed esters . the c 1 - c 20 hydrocarbyl esters include those derived from hydrocarbyl radicals of c 1 - c 20 hydrocarbons having acyclic , alicyclic , and aromatic structures such as those disclosed in the text &# 34 ; handbook of hydrocarbons &# 34 ;, ferris , s . w . academic press , inc ., new york , n . y ., ( 1955 ), pages 145 - 249 , all of which are incorporated herein by reference . the preferred esters suitable for use in preparing the novel compositions of the present invention are the c 1 - c 10 hydrocarbyl monoand diesters of the polymethylated muconic acids disclosed above . examples of the c 1 to c 10 hydrocarbyl groups include methyl , ethyl , butyl , pentyl , hexyl , heptyl , octyl , nonyl , decyl cyclopentyl , methyl cyclopentyl , dicyclopentyl , cyclohexyl , phenyl , tolyl , xylyl , naphthyl , tetrahydronaphthyl , decahydronaphthyl , as well as the various isomers of each . as aforestated , the diester of the meconic acid can be a mixed ester . an illustrative example is the cis - cis isomer of α , α &# 39 ;- dimethylmuconic acid which can be illustrated by the following structural formula : ## str4 ## wherein r 1 is different from r 2 . that is to say , r 1 can be a hydrocarbyl group of c 1 to c 20 and r 2 can be a different hydrocarbyl group of c 1 to c 20 , e . g ., r 1 may be cyclohexyl ( c 6 ) while r 2 is eicosyl ( c 20 ). examples of some of the esters of the polymethylated muconic acids suitable for use in the compositions of the present invention include the cis - cis , cis - trans and trans - trans isomers of the mono - and di - methyl esters of α , β &# 39 ;- dimethylmuconic acid ; the mono - and di - phenyl esters of α , α &# 39 ;, β , β &# 39 ;- tetramethylmuconic acid ; the mono - and dinaphthyl esters of α , β , β &# 39 ;- trimethylmuconic acid ; the mono - and di - 5 , 6 - diethylacenaphthyl esters of α , α &# 39 ;- dimethyl - munconic acid ; the mono - and di - cyclohexyl ester of α , α &# 39 ;- dimethylmuconic acid ; the mono - and di - 1 , 2 - dimethylcycloheptyl esters of α , β &# 39 ;- dimethylmuconic acid ; the mono - and di - decahydronaphthyl esters of α , α &# 39 ;, β , β &# 39 ;- tetramethylmuconic acid ; the mono - and di - 1 , 3 - dipropylbenzyl esters of α , α &# 39 ;- dimethylmunconic acid ; the mono - and di - 2 , 9 - dimethyl - 4 , 7 - diisobutyldecyl esters of α , α &# 39 ;, β - trimethylmuconic acid ; and the mono - and di - anthracyl esters of α , β &# 39 ;- dimethylmuconic acid ; mono - and di - 2 , 6 , 10 - trimethyl decyl esters of α , α &# 39 ;, β , β &# 39 ;- tetramethylmuconic acid ; and the nonyl ethyl esters of α , α &# 39 ;- tetramethylmunconic acid . as noted above , polymethylated muconic acids can exist in three isomeric forms , viz ., cis - cis , trans - trans and cis - trans . as an example , the unsaturated diacid , α , α &# 39 ;- di - methylmuconic acid , can be depicted by the following structural formulas : ## str5 ## the preparation of each of these isomeric forms of the α , α &# 39 ;- dimethylmuconic acid has been described in the prior art by elvidge et al ., j . chem . soc ., pp . 1026 - 1033 ( 1952 ). these authors show that oxidation of p - xylenol by means of peracetic acid gave the cis - cis form of the acid . the other isomeric forms were obtained indirectly by conversion of the cis - cis form . also dimethyl esters of each of the three isomeric forms were prepared by shaking the respective dmma with etheral diazomethane . the cis - cis form of polymethylated muconic acids can also be obtained by biological oxidation of p - xylene utilizing special strains of microorganisms as disclosed in u . s . pat . no . 3 , 383 , 289 issued may 14 , 1968 of raymond et al . for purposes of this invention , it has been found that when the cis , cis - isomer is employed as the starting material , the product is the compound having the structural formula : ## str6 ## wherein r 1 , r 2 , r 3 and r 4 are as defined above , while the trans - trans - isomer provides the compound : ## str7 ## wherein r 1 , r 2 , r 3 and r 4 are as defined above . the cis - trans - isomer on the other hand , provides mixtures of both . a convenient method for preparing the novel dithiophosphate derivatives of the aforedescribed muconic acid esters is simply to react the desired ester with diethyl dithiophosphate at an elevated temperature , desirably from 50 °- 150 ° c , preferably at about 70 °- 90 ° c , for about 18 to 30 hours . suitable amounts of an oxidation inhibitor such as hydroquinone are desirably employed . the reaction product , after cooling , is then solvent extracted , e . g . with benzene , neutralized with an aqueous solution of sodium carbonate or the like , dried , and the solvent removed under vacuum to yield the dithiophosphate derivative . when the cis , cis - acid ester isomer is employed , it will be seen that the mole ratio of this compound to acid should be about 1 : 1 , preferably about 1 . 25 : 1 in order to maintain a slight excess of dithiophosphate . on the other hand , the trans , trans - acid ester isomer will require a 2 : 1 ratio of this compound to acid ester , preferably about 2 . 4 : 1 , to maintain a stoichiometric balance . as one means of illustrating the present invention the following examples are presented : to 59 . 4 g of cis , cis - dimethylmuconic acid dimethyl ester is added 37 . 6 g of diethyl dithiophosphate and 0 . 2 g of hydroquinone . the reaction mixture is heated at 75 ° c for 24 hours , cooled to room temperature , and mixed with 200 ml of benzene . the solution is then water - washed with a 10 % solution of sodium carbonate , the resulting organic layer dried with mgso 4 and thereafter concentrated under vacuum to remove the benzene . the residue comprises the product : ## str8 ## in accordance with the foregoing procedure , but substituting cis - cis dimethylmuconic acid ethyl ester for the corresponding dimethyl ester , there is obtained the compound : ## str9 ## to 59 . 4 g trans , trans - dimethylmuconic acid dimethyl ester is added 75 . 2 g of diethyl dithiophosphate and 0 . 2 g of hydroquinone . the reaction mixture is heated at 85 ° c for 20 hours , cooled to room temperature , and mixed with 200 ml of benzene . the solution is then water - washed with a 10 % solution of sodium carbonate , the resulting organic layer dried with mgso 4 , and thereafter concentrated under vacuum to remove the benzene . the residue comprises the product : ## str10 ## in accordance with the foregoing procedure , but substituting trans , trans - dimethylmuconic acid methyl ethyl diester for the corresponding dimethyl ester , there is obtained the compound : ## str11 ## also according to this invention there is provided a novel insecticide composition having as at least one of its essential active ingredients each of the muconic acid ester isomers enumerated above . according to the invention , when these esters are admixed with , compounded with or dissolved in a suitable liquid or solid carrier in amounts of 1 to 30 percent by weight based on the total weight of the composition , they are effective for killing insects . for example , a 5 % solution of any one of the abovedefined muconic acid esters dissolved in 5 - 15 % methyl ethyl ketone or acetone , or the like , the balance consisting of petroleum spirits , when tested against the common housefly using the standard peet grady method , provides a substantial kill of the total number of flies as compared with the official test insecticide . alternatively , a solid carrier such as a wettable clay may be employed in the above composition . a test of methyl ethyl ketone and petroleum spirits indicates that the insecticidal efficacy of the composition of the invention is primarily due to the muconic acid esters , and not these solvents .