GB1580533A

GB1580533A - Cyanoacetic acid esters

Info

Publication number: GB1580533A
Application number: GB2826176A
Authority: GB
Original assignee: Shell Internationale Research Maatschappij BV
Current assignee: Shell Internationale Research Maatschappij BV
Priority date: 1976-07-07
Filing date: 1976-07-07
Publication date: 1980-12-03
Also published as: IT1143740B; DE2730332A1; DK156954B; DK302677A; NL188638C; JPS618823B2; NL7707417A; CA1123007A; BE856489A; FR2357533A1; NL188638B; MX4913E; FR2357533B1; BR7704405A; DK156954C; JPS537621A; CH628879A5

Abstract

The cyanoacetic esters of the general formula I in which R represents an aliphatic or cycloaliphatic group are valuable intermediates for the preparation of pesticides. These esters are prepared by reacting an alkali metal salt of cyanoacetic acid with a halide of the formula R-Hal in the presence of a phase-transfer catalyst and of an organic solvent. <IMAGE>

Description

(54) CYANOACETIC ACID ESTERS (71) We, SHELL INTERNATION- ALE RESEARCH MAATSCHAPPIJ B.V., a company organised under the laws of The Netherlands, of 30 Carel van Bylandtlaan, The Hague, The Netherlands, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- This invention relates to a process for the preparation of an ester of cyanoacetic acid which is a valuable chemical intermediate, especially in the preparation of pesticides such as esters of 2 - (2,2 - dichlorovinyl) - cyclopropanecarboxylic acid.

The present invention provides a process for the preparation of an ester of cyanoacetic acid having the following general formula:

(wherein R represents an aliphatic or cycloaliphatic hydrocarbyl group), which comprises reacting an alkali metal carboxylate of general formula:

(wherein M represents an alkali metal atom) with a hydrocarbyl halide of general for mula:- R - Hal (III) (wherein R has the meaning hereinbefore defined and Hal is a halogen atom having an atomic number of at least 17) in the presence of a phase transfer catalyst and an organic solvent.

In the reaction of an alkali metal carboxylate of the general formula II with a halide of the general formula III in the presence of a phase transfer catalyst, an undesirable side-reaction may take place with the formation of compounds of the general formula:

wherein R has the same meaning as in the general formula I; the latter reaction tends to occur at temperatures above 100"C and is clearly undesirable because it decreases the yield of the desired compounds of the general formula I. An attractive feature of the process according to the invention is that it allows the use of a relatively low reaction temperature, for example from 20 to 1000 C, and thereby avoids the production of substantial quantities of unwanted by-products; a low yield of by-product IV is particularly noticeable when the organic solvent is a halogenated hydrocarbon, especially a chlorinated hydrocarbon of 11 to 4 carbon atoms, e.g. tetrachloromethane, chloroform, dichloromethane and perchloroethylene, or an aromatic hydrocarbon especially an alkylbenzene, e.g. toluene or a xylene or mixture of xylenes. Carbon tetrachloride and xylene have shown excellent properties in this respect.

The halides of the general formula III may be primarv, secondary or tertiary. The carbon-carbon bonds in the aliphatic or cycloaliphatic hydrocarbyl group R may all be saturated or one or more of them may be unsaturated. The process according to the present invention is of particular importance when R in the general formula III represents a group of the general formula:

wherein R1, R2, R3, R4 and IR each represent a hydrogen atom or an aliphatic or cycloaliphatic hydrocarbyl group, for example an alkyl or a cycloalkyl group or a combination of any of these atoms and groups because intermediates for the preparation of particularly valuable pesticides are obtained. Moreover, halides of the general formula III wherein R represents a group of the general formula V are generally stable and do not decompose at a temperature below 100"C.

Preferably R2, R3 and R4 in the general formula V each represent a hydrogen atom or a methyl group and R1 and Ro represent hydrogen atoms. The preferred starting compound of the general formula III is l-chloro3 -methyl-2-butene.

In the alkali metal carboxylate of general formula II the alkali metal atom K may be lithium, sodium, potassium, rubidium or cesium but, for economic reasons, sodium or potassium are generally preferred. Very good results have been obtained with potassium cyanoacetate.

The phase transfer catalyst may be any reagent which is capable of accelerating interphase reactions taking place in two-phase systems and may take the form of an onium salt, a macrocyclic polyether, or a surfaceactive agent.

The phase transfer catalyst may be an onium salt, particularly a quaternary onium salt of the general formula:

wherein X represents a nitrogen, phosphorus or arsenic atom, R6, R7, R8 and R9 each an alkyl, aralkyl, alkaryl or aryl group and Y a monovalent ion, e.g. a halide such as chloride, bromide or iodide, or an alkylsulphate such as methylsulphate or ethylsulphate or a sulphonium salt of the general formula:

wherein R' , R" and R12 each represent an alkyl group and Y a monovalent ion, e.g. a halide such as chloride, bromine or iodide, or an alkylsulphate such as methylsulphate or ethylsulphate. Preferably the alkyl groups contain 1 to 18 carbon atoms and the aralkyl and alkaryl groups contain up to 10 carbon atoms; the aryl group is preferably phenyl.

Examples of suitable onium salts are tetran - butylammonium bromide, tetra - n - butylammonium chloride, methyltrioctyl - ammonium chloride, methyltri - (2 - methylheptyl) ammonium chloride, methyltri - 2 - methylphenyl - ammonium chloride, tetramethylphosphonium iodide, tetra - n - butylphos- phonium bromide, ethyl - 2 - methylpentyl2 - methylundecylsulphonium ethylsulphate, methyltriphenylarsonium iodide, ethyl - 2methylpentadecyl - 2 - methylundecylsulphonium ethylsulphate, methyldinonyl - sulphonium methylsulphate and n - hexadecyl dimethylsulphonium iodide. Very good results have been obtained with quaternary ammonium compounds.

The onium salt may be a hydroxide or a salt and can be employed as the functional portion of a strongly-basic anion exchange resin having a structural portion (polymer matrix) and a functional portion (ion-active group). Of special importance are polystyrene resins, such as copolymers of aromatic monovinyl compounds and aromatic polyvinyl compounds, particularly styrene/divinylbenzene copolymers. The functional portion is a quaternary ammonium, phosphonium or arsonium group. Examples of strongly-basic anion exchange resins which may be employed are those derived from trimethylamine (such as the products known under the trade names of "Amberlite IRA-400", "Amberlite IR 401", "Amberlite IRA-402", "Amberlite IRA 900", "Duolite A-101-D", "Duolite ES-111", "Dowex-1", "Dowex 11", "Dowex 21K" and "Ionac A-450"), and some of those derived from dimethlethanol amine (such as the products known under the trade names of "Amberlite IRA-410", "Amberlite IRA-911", "Dowex 2", "Duolite A-102-D", "Ionac A 542" and "Ionac A-550"). Very good results have been obtained with those derived from trimethylamine.

Other suitable phase transfer catalysts are macrocyclic polyethers known as "crown ethers". These compounds, together with their preparation, are described in the literature, for example in Tetrahedron Letters Nos. 18 (1972), pages 1793-1796, and are com monly designated by reference to the total number of atoms forming the macro cyclic ring together with the number of oxygen atoms in that ring. Thus the macrocyclic polyether whose formal chemical name is 1,4,7,10,13,16 - hexaoxacycloocta decane is designated as "18 - crown - 6".

Other examples of suitable macrocyclic polyethers are 3,4 - benzo - 1,6,9,12,15,18,21 heptaoxacyclotricos - 3 - ene 3,4 - benzo - 1, 6,9,12 - tetra - oxacyclotetradec - 3 - ene.

18 - Crown - 6 is particularly suitable.

Other suitable phase transfer catalysts are surface-active agents. A "surface-active agent" is defined as in Kirk-Othmer, "Encyclopedia of Chemical Technology", second edition, volume 19 (1969), page 508: "An organic compound that encompasses in the same molecule two dissimilar structural groups, one being water-soluble and one being waterinsoluble".

The surface-active agent is preferably nonionic, such as a poly(alkyleneoxy) derivative formed by reacting a higher alcohol, alkylphenol or fatty acid with ethylene oxide or propylene oxide. Suitable alcohols, alkylphenols or fatty acids contain an alkyl group of 8-20 carbon atoms and the number of alkyleneoxy units is in the range of 1-50. A particularly suitable non-ionic surface-active agent is formed from a C6~C11 n-alkanol mixture and contains an average of six ethyleneoxy units. The non-ionic surfaceactive agent may be an alkylbenzene containing a straight alkyl group. Suitable alkylbenzenes contain an alkyl group of 8-20 carbon atoms.

The molar ratio of the phase transfer catalyst to the halide of the general formula III can vary within wide limits, but is suitably from 1:5 to 1:5,000 and preferably from 1:20 to 1:200. The molar ratio of the alkali metal carboxylate of the general formula II to the halide of the general formula III can also vary within wide limits, but is suitably from 1:0.75 to 1:1, the equimolar ratio being preferred.

The process may suitably be carried out by stirring the starting compounds, the phase transfer catalyst and the organic solvent for periods of up to five hours at temperatures from 20 to 1000C.

The compound of the general formula I may be isolated from the reaction mixture by washing it with water to remove the simultaneously formed alkali metal halide, drying the washed mixture and fractionating the dried mixture.

Compounds generated by the process according to the invention and having the following general formula are novel com pounds and, accordingly represent another feature of the present invention:

wherein each R1, R2, R3, R4 and R5 independently represents a hydrogen atom or an aliphatic or cycloaliphatic hydrocarbyl group, e.g. an alkyl group of 1 to 4 carbon atoms such as a methyl group provided that at least one of R1, R2, R3, R4 and R5 is a hydrocarbyl group. An example of such a novel compound is 3 - methyl - 2 - butenyl cyanoacetate.

The following examples illustrate the process according to the invention and the novel compounds produced therefrom.

EXAMPLES I to VI.

A vessel was charged with 25 mmol of potassium cyanoacetate, 25 mmol of 1 - chloro 3 - methyl - 2 - butene, tetra - n - butyl ammonium chloride and 25 ml of a solvent.

The contents of the vessel were stirred for a certain period. The mixture formed was washed twice with 10 ml of water, the washed mixture was dried in the presence of anhydrous magnesium sulphate, the magnesium sulphate was removed by filtration and the filtrate was boiled down. Analysis by means of gas-liquid chromatography showed that the residue consisted of 3 - methyl - 2 - butenylcyanoacetatae (x mmole) and 3 - methyl - 2butenyl 2 - cyano - 5 - methyl - 4 - hexenoate (y mmole). The conversion of 1 - chloro - 3 methyl - 2 - butene, expressed in % was calculated as x + 2y 25 The selectivities to 3 - methyl - 2 - butenyl cyanoacetate and 3 - methyl - 2 - butenyl 2 - cyano - 5 - methyl - 4 - hexenoate, expressed in % were calculated as x 2y X X 100 and X 100, x + 2y 2 + 2y respectively. The yield of 3 - methyl - 2butenyl cyanoacetate, expressed in %, was calculated as Conversion of 1 - chloro - 3 - methyl - 2 butene x selectivity to 3 - methyl - 2 butenyl cyanoacetate 100 Six experiments were conducted in the manner described above. The table shows the solvents used, the amounts of tetra-n-butylammonium chloride employed, calculated on 1 - chloro - 3 - methyl - 2 - butane, the temperatures, the reaction times and the results.

TABLE Selectivity, %, to 3-methyl-2-butenyl Tetra-n-butyl- Conversion of ammonium Reaction 1-chloro- Yield, % Example chloride Temperature, time, 3-methyl- cyano- 2-cyano-5-methyl of 3-methyl-2 No. Solvent % mole C h 2-butene, % acetate 4-hexenoate butenyl cyanoacetate I CCl4 2 90 4 92 98 2 90 II CHCl3 5 77 4 92 86 14 79 III CH2Cl2 20 36 2 95 82 18 78 IV xylene1) 2 70 7 78 95 5 74 V ditto 1 110 1 90 62 38 56 VI ditto 20 115 1 99 53 47 53 1) a mixture of o-, m- and p-xylene.

Claims

The NMR spectrum of 3 - methyl - 2butenyl cyanoacetate measured at 60 MHz in deuterochloroform solution showed the following absorptions relative to a tetramethylsilane standard: # = 1.7-1.8 ppm (two doublets, two CH3) # = 5.37 ppm (multiplet = CH) # = 4.67 ppm (doublet, CH2O) # = 3.53 ppm (singlet, CH2CN) WHAT WE CLAIM IS:1. A process for the preparation of an ester of cyanoacetic acid having the following general formula:

(wherein R represents an aliphatic or cycloaliphatic hydrocarbyl group), which comprises reacting an alkali metal carboxylate of general formula:-

(wherein M represents an alkali metal atom) with a hydrocarbyl halide of general formla: R - Hal (III) (wherein R has the meaning hereinbefore defined and Hal is a halogen atom having an atomic number of at least 17) in the presence of a phase transfer catalyst and an organic solvent.
2. A process according to claim 1, in which the phase transfer catalyst is an onium salt, a macrocyclic polyether, or a surface-active agent.
3. A process according to claim Z, in which the phase transfer catalyst is a quaternary onium salt of the general formula:

wherein X represents a nitrogen, phosphorus or arsenic atom, R6, R7, R9 and R9 each an alkyl, aralkyl, alkaryl or aryl group and Y a monovalent ion, or a ternary sulphonium salt of the general formula:

wherein R10, R1l and R12 each represents an alkyl group and Y a monovalent ion.
4. A process according to claim 2 or 3 wherein the phase transfer catalyst is a quaternary ammonium salt.
5. A process according to claim 4 wherein the quaternary ammonium salt is tetra-butylammonium chloride.
6. A process according to any one of the preceding claims wherein the organic solvent is a halogenated hydrocarbon or an aromatic hydrocarbon.
7. A process according to claim 6 wherein the halogenated hydrocarbon is a chlorinated hydrocarbon containing 1 to 4 carbon atoms.
8. A process according to claim 7 wherein the chlorinated hydrocarbon is carbon tetrachloride.
9. A process according to claim 6 wherein the aromatic hydrocarbon is xylene.
10. A process according to any one of the preceding claims wherein the reaction takes place at a temperature in the range 20C to 1000C.
11. A process according to any one of the preceding claims wherein R represents a group of formula:

wherein R1, R2, R3, R4 and R5 each represent a hydrogen atom or an aliphatic or cycloaliphatic hydrocarbyl group.
1.2. A process according to claim 11 wherein R2, R3 and R4 represent hydrogen or a methyl group and R1 and R5 represent hydrogen atoms.
13. A process according to Claim 1 substantially as hereinbefore described and with reference to any one of the Examples.
14. Esters of cyanoacetic acid when prepared by the process claimed in any one of the preceding claims.
15. Compounds of formula:

wherein R1, R2, R3, R4 and R5 each inde- pendently represent a hydrogen atom or an aliphatic or cycloaliphatic hydrocarbyl group, provided that at least one of R1, R2, R3, R4 and R5 is a hydrocarbyl group.
16. Compounds according to claim 15 wherein R1, R2, R3, R4 and R5 each inde- pendently represent a hydrogen atom or an alkyl group of 1 to 4 carbon atoms, provided that at least one of Rl, R2, R3, R4 and R5 is an alkyl group of 1 to 4 carbon atoms.
17. 3-Methyl-2-butenyl cyanoacetate.