Preparation of substituted alpha-halogeno-propionic acids and their derivatives

Substituted .alpha.-halogenopropionic acids and their derivatives of the general formula ##STR1## wherein R.sup.1 to R.sup.3, Y and X have the meanings given in the description, are prepared by a process which is characterized in that substituted vinylidene chlorides of the general formula ##STR2## are reacted with chlorine or bromine chloride in the presence of compounds of the formula EQU R.sup.5 --SO.sub.3 R.sup.6 (III) wherein R.sup.5 and R.sup.6 have the meaning given in the description, and the products obtained are treated, if appropriate, with water or alcohol. Certain of the substituted .alpha.-halogeno-propionic acids and the substituted vinylidene chloride of the formula ##STR3## are new. The end products are useful as herbicides and intermediates for insecticides.

The present invention relates to an unobvious process for the production of 
certain substituted .alpha.-halogenopropionic acids and their derivatives, 
some of which are known, and to new intermediate products for their 
production. 
It has already been disclosed that vinylidene chlorides, which are 
substituted by aromatic groups, can be converted into the correspondingly 
substituted .alpha.-halogenoacetic acid derivatives by halogenation in 
formic acid. However, this reaction was not known in the case of 
vinylidene chlorides substituted by aliphatic groups (see Chemical 
Abstracts 54; 1333 (1960)). 
The present invention now provides a process for the production of a 
substituted .alpha.-halogenopropionic acid or a derivative thereof of the 
general formula 
##STR4## 
in which R.sup.1 represents a hydrogen or halogen atom or an alkyl, 
halogen-substituted alkyl or aryl group, 
R.sup.2 and R.sup.3 independently of each other represent a hydrogen or 
halogen atom or a methyl or ethyl group, 
Y denotes a chlorine atom, a hydroxyl group or a group of the general 
formula OR.sup.4, 
in which 
R.sup.4 represents a C.sub.1 to C.sub.8 alkyl group, and 
X represents a chlorine or bromine atom, 
which is characterized in that a substituted vinylidene chloride of the 
general formula 
##STR5## 
wherein R.sup.1, R.sup.2 and R.sup.3 have the meanings given above, is 
reacted with chlorine or bromine chloride in the presence of a compound of 
the general formula 
EQU R.sup.5 --SO.sub.3 R.sup.6 (III) 
wherein 
R.sup.5 represents an optionally halogen-substituted C.sub.1 to C.sub.18 
alkyl group, an optionally alkyl-substituted aryl group, a C.sub.1 to 
C.sub.8 alkoxy group, a chlorine or fluorine atom or a hydroxyl group and 
R.sup.6 represents a hydrogen atom or a methyl or ethyl group, 
and the product obtained is treated, if a compound of formula (I) in which 
Y represents a hydroxyl group or a group of the general formula OR.sup.4 
is required, with water or an alcohol R.sup.4 OH, respectively, wherein 
R.sup.4 has the meaning given above. 
The present invention further provides, as new compounds, substituted 
.alpha.-halogenopropionic acids of the general formula 
##STR6## 
wherein R.sup.1 represents a hydrogen atom or a C.sub.1 to C.sub.4 alkyl 
group which is optionally substituted by halogen, 
R.sup.2 represents a hydrogen atom or a C.sub.1 to C.sub.4 alkyl group 
which is optionally substituted by halogen, 
R.sup.3 represents a halogen-substituted C.sub.1 to C.sub.4 alkyl group, 
Y represents a chlorine atom, a hydroxyl group or a radical of the general 
formula OR.sup.4, wherein 
R.sup.4 represents a C.sub.1 to C.sub.8 alkyl group, and 
X represents a chlorine or bromine atom. 
According to the present invention, we further provide, as a new compound, 
the substituted vinylidene chloride of the formula 
##STR7## 
The present invention further provides a process for the production of the 
new substituted vinylidene chloride of the formula (IV), as defined above, 
which is characterized in that 1,3,3,3-tetrachloro-1,1-dimethyl-propane is 
reacted with vinyl chloride in the presence of a Lewis acid. 
It is surprising that the process according to the invention for the 
production of compounds of formula (I) is applicable for the whole range 
of such compounds and proceeds with good yields in being carried out in 
the presence of the sulphonic acid and its esters of the formula (III), 
and not, as known from the state of the art, in formic acid. The process 
of the present invention for the production of compounds of formula (I) 
also has the advantage that the sulphonic acids and their esters of 
formula (III), which are used as the reaction medium, can readily be 
recovered. 
If 1,1,5,5-tetrachloro-3,3-dimethyl-pent-1-ene is used as the starting 
compound, the process according to the invention for the production of 
compounds of formula (I) is illustrated by the following scheme: 
##STR8## 
The process according to the present invention is preferably used to 
produce compounds of the formula (I) 
wherein 
Y has the meaning given above, 
X represent a chlorine atom, 
R.sup.1 represents a hydrogen atom or a C.sub.1 to C.sub.13 alkyl group 
which is optionally substituted by fluorine, chlorine or bromine (and 
preferably a hydrogen atom, a C.sub.1 to C.sub.13 alkyl group or a C.sub.1 
to C.sub.4 alkyl group which is substituted by 1 or 2 chlorine or fluorine 
atoms); and 
R.sup.2 and R.sup.3 independently represent a hydrogen or halogen atom or a 
methyl or ethyl group (and preferably a hydrogen or chlorine atom or a 
methyl group). 
In addition to the compounds of the formula (I) mentioned in the 
preparative examples, the following compounds are particularly preferred: 
2,5-dichloro-3,3-dimethyl-pentanoic acid, 
2-chloro-5-fluoro-3,3-dimethyl-pentanoic acid, 
2,5,5-trichloro-3,3-dimethyl-pentanoic acid. 
2-bromo-5,5-dichloro-3,3-dimethyl-pentanoic acid, 
2-chloro-2-bromo-3-methyl-butanoic acid and 2-bromo-3,3-dimethyl-butanoic 
acid, as well as the acid-chlorides, and methyl, ethyl, n-propyl, 
i-propyl, n-butyl, i-butyl, sec.-butyl and tert. butyl esters of these 
acids. 
The process according to the invention for the production of compounds of 
formula (I) is generally carried out at a temperature between -20.degree. 
C. and 100.degree. C., preferably between 0.degree. and 50.degree. C. 
The reaction is generally carried out under normal pressure or under 
slightly elevated pressure. 
The halogenating agent is generally employed in an equivalent quantity 
relative to the vinylidene chlorides of the formula (II) employed, that is 
to say 1 mol of chlorine or 2 mol of bromine chloride are used per mol of 
the compound of the formula (II). 
The following are examples of compounds of the formula (III) used in the 
process according to the present invention: 
sulphonic acids and sulphonates, such as methanesulphonic acid, 
ethanesulphonic acid, chloromethanesulphonic acid, benzenesulphonic acid, 
o-toluenesulphonic acid, p-toluenesulphonic acid, 
i-dodecylbenzenesulphonic acid and methyl methanesulphonate, or sulphuric 
acid monoesters and diesters, such as dimethyl sulphate and diethyl 
sulphate, or C.sub.1-8 -alkyl and benzyl esters of chlorosulphonic acid, 
fluorosulphonic acid and sulphuric acid. 
The reaction is particularly preferably carried out in the presence of the 
following compounds of the formula (III): 
sulphuric acid, methanesulphonic acid, monomethyl sulphate, monoethyl 
sulphate and i-dodecylbenzenesulphonic acid. 
The process according to the invention is preferably carried out without a 
solvent. However, the reaction can also be carried out in the presence of 
a solvent which is inert with respect to the halogenating agents used. 
Chloro-hydrocarbons, such as dichloromethane or dichloroethane, may be 
mentioned as examples of such solvents. 
The process according to the invention is generally carried out in such a 
manner that the compounds of the formula (II), if appropriate dissolved in 
a solvent which is inert to halogens, are mixed with the compounds of the 
formula (III), and chlorine is introduced into this mixture. The end of 
the reaction may be determined by extracting, with hexane, a sample of the 
reaction mixture and investigating the extract by IR spectroscopy. The 
disappearance of the absorption bands at 1,600 cm.sup.-1, which is 
characteristic for compounds of the formula I, indicates the end of the 
reaction. 
To conduct away excess heat of reaction, it may be necessary to cool the 
mixture. 
The isolation of the compounds of the formula (I) can be effected by 
extraction, for example with hydrocarbons such as pentane, hexane or light 
petrol. However, the compounds of the formula (I) can also be separated 
off from the reaction mixture by means of distillation. 
If a compound of formula (I) which is an ester Y=OR.sup.4) or an acid 
(Y=OH) is to be obtained, it is advantageous to add at least an equivalent 
quantity of an appropriate alcohol or water to the reaction mixture, and 
to remove the ester or the acid from the reaction mixture by means of 
extraction or distillation. 
As already mentioned, some of the compounds of the formula (I) which can be 
prepared by the process according to the process of the present invention 
are new. 
Among these, the following new compounds are preferred: 
2,5-dichloro-3,3-dimethyl-pentanoic acid, 
2,5,5-trichloro-3,3-dimethyl-pentanoic acid, 
2-bromo-5,5-dichloro-3,3-dimethyl-pentanoic acid and 
2-chloro-5-fluoro-3,3-dimethyl-pentanoic acid. 
The new compounds of the formula (I) can be employed as herbicides. 
However, some of them can also be further processed, in a process which 
does not yet belong to the state of the art, to give the known 
caronaldehyde acid. This process can be represented by the following 
scheme: 
##STR9## 
For this purpose, compounds of the formula (I) are treated, in 
water-containing solvents with bases such as alkali metal hydroxide or 
alkaline earth metal hydroxide, and the resulting salts of carbonaldehyde 
acid are acidified and the acid is isolated in the customary manner. 
Some of the new compounds can also be further processed, in a process which 
does not yet belong to the state of the art, to give the known 
permethrinic acid. This process can be represented by the following 
scheme: 
##STR10## 
In this process, the individual process stages are carried out analogously 
to known processes. 
The invention also relates to the process for the preparation of the novel 
substituted vinylidene chloride of the formula 
##STR11## 
This compound is prepared by the previously mentioned further process 
according to the present invention. This process can be represented by the 
following equation: 
##STR12## 
The reaction is generally carried out at a temperature between -20.degree. 
C. and +30.degree. C., preferably a temperature between -5.degree. and 
+30.degree. C. It is preferably carried out without a solvent. However, 
inert organic solvents, such as halogeno-hydrocarbons (for example 
methylene chloride) can also be used. 
The tetrachlorodimethylpropane and vinyl chloride are generally employed in 
an equimolar ratio. The reaction is carried out in the presence of a Lewis 
acid. AlCl.sub.3, AlBr.sub.3, BeCl.sub.2, ZnCl.sub.2, BF.sub.3, 
TiCl.sub.4, SnCl.sub.4, SbCl.sub.5 and FeCl.sub.3 are examples of suitable 
Lewis acids. The following are preferably used: AlCl.sub.3, FeCl.sub.3, 
ZnCl.sub.2 and TiCl.sub.4. 
Surprisingly, the reaction proceeds with a good selectivity, although 
secondary reactions of the resulting new vinylidene chlorides of the 
formula (II), and elimination reactions of the tetrachlorodimethylpropane 
as well as the vinylidene chloride were to have been expected. 
Some of the remaining compounds of the formula (II) which are used as 
starting materials for the process according to the invention for the 
production of a compound of formula (I), are known or are obtained 
analogously to known processes (see, for example, J. Am. Chem. Soc. 74, 
2885 (1952) or Application Ser. No. 281,614, filed July 9, 1981, now 
pending, which does not yet belong to the state of the art).

The following examples merely serve to illustrate the processes of the 
present invention. 
EXAMPLE 1 
182 g of 1,1,5,5-tetrachloro-3,3-dimethyl-pent-1-ene were dissolved in 400 
ml of methanesulphonic acid. 80 g of chlorine were introduced into the 
solution at 10.degree. to 20.degree. C. (cooling with water). The reaction 
was allowed to continue until a sample, which was obtained by extracting 
the reaction mixture with hexane, showed no IR absorption at 1,610 
cm.sup.-1. The complete reaction solution was then extracted with hexane. 
156 g (=80% of theory) of 2,5,5-trichloro-3,3-dimethylpentanoic 
acid-chloride of the boiling point range 92.degree. to 95.degree. C./0.12 
mm Hg were obtained from the hexane phase by vacuum distillation, after 
the hexane had been expelled. 
EXAMPLE 2 
Preparation of the starting materials 
75 g of vinyl chloride were introduced into a solution of 15 g of 
AlCl.sub.3 in 1,000 ml of methylene chloride at -20.degree. C., and 500 g 
of 1,3,3,3-tetrachloro-1,1-dimethyl-propane and a further 105 g of vinyl 
chloride were simultaneously metered into the reaction solution during the 
course of 180 minutes. The reaction mixture was thereafter allowed to 
react further for 180 minutes at -10.degree. C., and 1,000 ml of water 
were then added to the solution. After the separation, the aqueous phase 
was extracted several times with methylene chloride, and the combined 
organic phases were dried with zeolite and fractionally distilled. 230 g 
of the starting material of the boiling point range 32.degree. to 
37.degree. C. 0.1 mm Hg and 270 g of 
1,1,5,5-tetrachloro-3,3-dimethyl-pent-1-ene (a compound of the formula 
(II)) of the boiling point range 72.degree. to 76.degree. C./0.15 mm Hg 
were obtained. This result corresponded to a conversion of 54% with a 
selectivity of 88%. 
EXAMPLE 3 
Further processing of the product obtained according to Example 1 to give 
caronaldehyde acid 
100 ml of water are initially introduced into a stirred vessel and heated 
to 100.degree. C. 63 g (0.25 mol) of 2,5,5-trichloro-3,3-dimethylpentanoic 
acid-chloride and a solution of 58 g of NaOH in 100 ml of water were then 
simultaneously added dropwise, the pH being monitored, at such a rate that 
a pH value in the range of 9 to 10 was maintained. The reaction had ended 
after 30 minutes. The reaction solution was cooled to 20.degree. C., 
adjusted to pH 2 with hydrochloric acid and extracted with 
dichloromethane. After the solvent had been expelled, 36 g of crude acid 
were obtained, and, after distillation in vacuo, 29.6 g (=83.4%) of pure 
trans-3-formyl-2,2-dimethyl-cyclopropane-1-carboxylic acid, boiling point 
125.degree. to 130.degree. C./0.5 mm Hg, were obtained. 
.sup.1 H-NMR: .delta.=1.3 (s, 3H), 1.35 (s, 3H), 2.46 (m, 2H) 9.55 (d, 
resolved, 1H) 10.95 (s, 1H) ppm. 
EXAMPLE 4 
A mixture of 160 g of Br.sub.2 and 71 g of Cl.sub.2 (BrCl), and 
simultaneously 208 g of 1,1-dichloro-3-methyl-butene, were added dropwise 
to 770 g of methanesulphonic acid, while stirring. The reaction mixture 
was kept at 20.degree. C. by cooling with ice. After a reaction time of 5 
hours, 400 ml of ethanol were added dropwise and the reaction mixture was 
left for a further 5 hours at 60.degree. C. The product mixture was then 
introduced onto 1 kg of ice and was extracted several times with toluene. 
159 g of ethyl 2-bromo-3-methyl-butanoate, boiling point 
80.degree.-81.degree. C./16 mm Hg, were obtained by fractional 
distillation of the organic phase. 
EXAMPLE 5 
600 g of 1,1,5-trichloro-3,3-dimethyl-pentene were added dropwise to 1,800 
g of methanesulphonic acid, and 250 g of chlorine were introduced into the 
methanesulphonic acid, the mixture being stirred and the reaction 
temperature being 15.degree. to 20.degree. C. After 6 hours, 1,000 ml of 
ethanol were added and the mixture was warmed to 80.degree. C. for a 
further 8 hours. After the working-up as in Example 4, 490 g of ethyl 
2,5-dichloro-3,3-dimethyl-pentanoic acid, boiling point 80.degree. to 
85.degree. C./0.3 mm Hg, were obtained. 
EXAMPLE 6 
336 g of 1,1,5-trichloro-3,3-dimethyl-pentene were reacted, in 1,000 g of 
methanesulphonic acid, with 210 g of chlorine, as described in Example 5. 
The end of the reaction was determined by IR spectroscopy. The reaction 
mixture was thereafter extracted several times with n-hexane. 252 g of 
2,5-dichloro-3,3-dimethyl-pentanoic acid-chloride, boiling point of 
65.degree.-68.degree. C./0.2 mm Hg, were obtained by fractional 
distillation of the hexane phase. 
EXAMPLE 7 
1,1-dichloro-3,3-dimethyl-5-fluoro-pentene was obtained by heating 500 g of 
1,1,5-trichloro-3,3-dimethyl-pentene with 200 g of KF in 1,500 g of 
sulpholane for 8 hours, followed by fractional distillation; the compound 
boiled at 60.degree. to 63.degree. C./12 mm Hg. 
58 g of 1,1-dichloro-3,3-dimethyl-5-fluoro-pentene was reacted with 39 g of 
chlorine in 193 g of methanesulphonic acid, as described in the examples 
above. After the reaction mixture had been extracted several times with 
n-hexane and the extracts had been fractionally distilled, 49 g of 
2-chloro-5-fluoro-3,3-dimethyl-pentanoic acid-chloride, boiling point 
75.degree.-78.degree. C./13 mm Hg, were obtained. 
EXAMPLE 8 
153 g of 1,1-dichloro-3,3-dimethyl-butene were reacted, in 500 g of 
methanesulphonic acid, with 151 g of BrCl, as indicated in Example 4. 
After the reaction had ended, the mixture was extracted with hexane and 
the extracts were worked up by distillation. 120 g of 
2-bromo-3,3-dimethyl-butanoic acid-chloride of the boiling point range 
60.degree. to 65.degree. C./15 mm Hg were obtained. 
EXAMPLE 9 
3,3-Dimethyl-1,1,5-trichloro-1-pentene 
20 g of aluminum chloride were dissolved in 2,300 g of 1,1-dichloro-ethene, 
while stirring and cooling to -10.degree. C. 1,286 g. of 
1,3-dichloro-3-methyl-butane were then added dropwise to the solution 
during the course of 3 hours, and, at intervals of 15 minutes, a further 3 
g of aluminum chloride in each case was simultaneously metered into the 
mixture, a reaction temperature of between 0.degree. C. and +5.degree. C. 
being maintained by cooling. After the reaction had eneded, 60 ml of 
acetic acid were added dropwise to the reaction mixture. The product 
mixture was thereafter filtered over Na.sub.2 SO.sub.4 and was then 
metered into a distillation apparatus, the bottom temperature being kept 
at 120.degree. C. and a pressure of 1 mbar being maintained; the 
distillate was cooled and condensed by a dry ice/acetone mixture. The 
crude distillate was then fractionated in vacuo in a Vigreux column. 
1,650 g (=90% of theory) of 3,3-dimethyl-1,1,5-trichloro-1-pentene were 
obtained. 
Boiling point 59.degree. to 63.degree. C./0.1 mm Hg. 
EXAMPLE 10 
23.6 g of 1,1,5,5-tetrachloro-3,3-dimethyl-pentene were added to 200 ml of 
concentrated sulphuric acid at 0.degree. C., and 15 g of chlorine were 
then introduced into the mixture at 10.degree. to 20.degree. C., the 
reaction mixture being stirred intensively. After a sample of the reaction 
mixture, after extraction with hexane, had shown by means of IR 
spectroscopy that the absorption at 1,600 cm.sup.-1 had vanished, excess 
chlorine was stripped off in vacuo. 400 ml of water were then added while 
stirring and cooling well, the temperature increasing to 70.degree. C. 
After the mixture had been extracted with methylene chloride and the 
solvent had been distilled off, 22 g of crude 
1,5,5-trichloro-3,3-dimethyl-pentanoic acid were obtained. This was 
converted into the acid-chloride by warming with 24 g of thionyl chloride, 
and the acid-chloride was isolated in pure form by fractional 
distillation. 17.2 g of 1,5,5-trichloro-3,3-dimethyl-pentanoic 
acid-chloride, boiling point 95.degree. to 98.degree. C./0.3 mm Hg, were 
obtained. 
It will be appreciated that the instant specification and examples are set 
forth by way of illustration and not limitation, and that various 
modifications and changes may be made without departing from the spirit 
and scope of the present invention.