DE1109662B - Process for the preparation of 2,4,4,4-tetrachlorobutyric acid - Google Patents

Description

The 2,4,4,4-tetrachlorobutyric acid is used according to one Proposal as an additive to lubricating oils to prevent seizing of parts moving against one another counteracting high loads and at the same time reducing wear. The problem of Production of tetrachlorobutyric acid with a high degree of purity and in good yield therefore has a gained particular importance.

A three-step process for the synthesis of 2,4,4,4-tetrachlorobutyric acid is already known according to which acrolein with alcohol or ethyl orthoformate to a diethyl acetal and this under the influence of UV light with carbon tetrachloride to form tetrachlorobutyraldehyde diethylacetal is implemented, followed by an oxidizing hydrolysis using nitric acid. The attachment however, the carbon tetrachloride to the acrolein diethyl acetal is one of numerous side reactions accompanied, some of which lead to unsaturated ethers, so that in practice the desired tetrachlorobutyric acid can only be obtained in a yield of about 18% based on the acrolein diethylacetal. In addition, the degree of purity of the product obtained in this way also leaves something to be desired. Another The disadvantage of this known method is the comparatively high price of the entire acetal, see above that this procedure is not suitable for a profitable industrial production.

These deficiencies are now remedied by the method of the invention which is the most readily available method of manufacture
of 2,4,4,4-tetrachlorobutyric acid

Applicant:

Directed by Nationale des Usines Renault,
Billancourt, Seine (France)

Representative: Dr. K. Schwarzhans, patent attorney,
Munich 19, Romanplatz 9

Claimed priority:
France 11 April 1957

and relatively cheap allyl acetate used as the starting material and in which the tetrachlorobutyric acid in a yield of up to about 30%> based on this starting product, in a satisfactory manner Degree of purity.

The process according to the invention is characterized by the sequence of three implementations:

1. Conversion of carbon tetrachloride with allyl acetate to 2,4,4,4-tetrachlorobutanol acetate:

CCl ₄ + CH ₂ = CH - CH ₂ - OOC - CH ₃ > CCl ₃ - CH ₂ - CHCl - CH ₂ - OOC - CH ₃

2. Implementation ("alcoholysis") of this acetate z. B. with methyl alcohol to 2,4,4,4-tetrachlorobutanol: CCl ₃ -CH ₂ -CHCl-CH ₂ -OOC -CH ₃ + CH ₃ OH

s> CCl ₃ -CH ₂ -CHCl-CH ₂ OH + CH ₃ -COOCH ₃

3. Oxidation of 2,4,4,4-tetrachlorobutanol to 2,4,4,4-tetrachlorobutyric acid:

3CCl ₃ - CH ₂ - CHCl - CH ₂ OH + 4CrO ₃

Details of these three reaction stages are described below:

1. You have already reacted carbon tetrachloride with allyl acetate in the presence of benzoyl peroxide, but up to now only mixtures of polymerization products of the general formula have been possible

CCl ₃ - (CH ₂ - CH) ₇₁ - Cl

CH ₂

CHo COO

> 3CC1 ₃ - CH ₂ - CHC 1 - COOH + 2Cr ₂ O ₃ + 3H ₂ O

obtained, but not the monomeric acetate of tetrachlorobutanol formulated above (cf. »Journal of American Chemical Society ", Vol. 76 [1954], pp. 457 to 464.) In the procedure according to the invention, in predominantly obtained the monomeric acetate. Here, the respondents are during the entire duration of the implementation, which must take place very slowly, gradually increasing with each other brought into contact. For example, the allyl acetate becomes carbon tetrachloride dropwise and also the catalyst, e.g. B. Benzoyl peroxide dissolved in carbon tetrachloride supplied so that the

109 619/431

3 4

Addition only after 30 hours with the end of the also a small amount of the diacetate of 2-chloro

Reaction is complete. During this reaction ((3, / S, / 3-trichloroethyl) -4-pentanediol-1,5

CCI ₃ -CH ₂ -CH-CH ₂ -CHCI-CH ₂ -OOC-Ch ₃
CH ₂

CH ₃ -COO

but not higher polymers. io anhydride; Amount of that contained in acetic acid

Apart from benzoyl peroxide, water can be used as a catalyst; Reaction temperature and reaction time.

Compound used that is free radicals One can regard these conditions very much

supplies. This includes B. acetyl, benzoyl, sharp boundaries, outside of either

Lauroyl, stearoyl peroxide, cumene, p-cumene, tert-the oxidation stops with the aldehyde formation or

Butyl, tert-amyl hydroperoxide and inorganic 15 lead to a breakdown of the oxidation product.

Per compounds, such as hydrogen peroxide, sodium It is necessary to have an excess of chromic acid

peroxide, sodium perborate, potassium persulfate and Al- from 25 to 100% to use in order to achieve sufficient

potash carbonates. One can also get ultraviolet light yield. A further one

use. Surplus would only save unnecessary costs

To get the best yield, the amount should be 20 causes.

of the catalyst between 1 and 10 percent by weight, the amount of that contained in the acetic acid

based on allyl acetate. Water has a significant influence on the oxy-

To prevent the formation of polymers, dation speed. In the absence of water

it is advisable to use an excess of tetrachloro the oxidation conditions are too severe, and it

carbon from 1 to 10 moles per mole of allyl acetate to 25 degrades the product. When the acid

use. The duration of the conversion depends on the too much diluted, the oxidation takes too long-

Amount of reactants, depending on the temperature sam. Satisfactory results are obtained if the

and on the type of catalyst used. Acetic acid contains 5 to 30% water.

The highest yield is obtained when one essentially depends on the duration of the oxidation

a temperature works at which the decomposition 30 from the amount of water contained in the acetic acid.

the peroxide takes place immediately. It must be at least 5 to 6 hours. It is

2. During the alcoholysis of an ester, however, there are no concerns about using it on one Equilibrium reaction represents, in general, only extend a longer period of time if one is at gives mediocre yields, the present room temperature has been working.

Process very favorable equilibrium conditions 35 The oxidation of tetrachlorobutanol is strong

as a result, so that the yield of tetrachlorobutanol is exothermic. One must therefore use the reaction mixture

is close to 100%. During the addition of the chromic anhydride, strong alcoholysis can occur

Successfully cool methyl, ethyl and isopropyl alcohol. The mixture will then be at least 5 to

be used. The equilibrium is shifted and left to stand at room temperature for 6 hours. To

In favor of the tetrachlorobutanol by using it for about 30 hours, the implementation has come to a standstill

a large excess of alcohol, e.g. B. from 5 to come. To reduce the response time, can

20 moles per mole of tetrachlorobutanol acetate. The around the reaction mixture after 15 to 20 hours

Setting is achieved by a very small amount of a constant reaction time at room temperature

strong acid, such as hydrochloric acid, sulfuric acid or even 1 to 2 hours at a temperature of

Phosphoric acid, catalyzed. For the best yield to 45 30 to 40 ⁰ C heat.

obtained, the amount of the catalyst, calculated The following example explains the invention to 1 mole of tetrachlorobutanol acetate, between 0.001 according to the method in more detail,
and 0.1 moles.

The duration of the reaction depends on the working template

temperature. Prolonged heating, which results in 50 stage 1: 1078 g (7 moles) of anhydrous tetrachloride partial decomposition of the reactants, carbon will boil under reflux must be avoided. The cheapest way of working is heated. With the help of a suitable device adds consists in working in two stages. one dropwise 400 g (4 mol) of freshly distilled First, implementation of longer duration with space allyl acetate and a solution of 32 g (0.132MoI) temperature and then briefly light 55 benzoyl peroxide in 2002 g (13 mol) carbon tetrachloride heating, to complete the reaction. fabric too. The rate of addition of the allyl acetate

3. The known method of oxidation of Aiko and the catalyst solution is regulated in such a way that fetching carboxylic acids by means of a mixture of the addition of the total amount in the course of 30 hours of acetic and chromic acid has not yet taken place. Tetrachlorobutanol is then refluxed for ^x / _{a hour.} It has continued to 60. The reaction mixture is then clear and has now shown that this reaction easily turns it a light yellow color.

allows 2,4,4,4-tetrachlorobutyric acid in proportion- The fractional distillation of the reaction

to obtain moderately high yield. mix gives the following results:

The oxidation is carried out with an excess of a) At ordinary pressure, 2330 g is obtained under Chromic anhydride, which is in acetic acid, which only has a 65 80 ° C boiling forerun, which for the most part

contains a small amount of water, is dissolved. For which is made of carbon tetrachloride.

The course of the oxidation are the following four points b) At 93 to 95 ° C / 1 mm, 632 g (62%,

determining: amount of the excess of chromic acid - based on allyl acetate) 2,4,4,4-tetrachlorobutanol-

acetate, which has a refractive index «I? = 1.4830; Elemental analysis: found C 29.16%, H 3.26%, 011.13%, Cl56.57% (calculated C28.40%, H3.18%, O 12.6%, Cl 55.8%).

c) At 133 ° C./1.5 mm, 147 g (20% based on allyl acetate) of the diacetate of 2 chlorine - (/?, /?, / S-trichloroethyl) -4-pentanediol-1.5, the one Refractive index n ^s g = 1.4860.

Step 2: A solution of 1016 g (4 mol) of tetrachlorobutanol acetate in 800 cm ^{3 of} methanol (20 mol) is ^{prepared with the addition of 16 cm 3 of} concentrated chloroacetic acid (density 1.19), and this solution is left to stand for 24 hours. The excess of methanol and ethyl acetate is evaporated on a water bath. The residue is again dissolved in 800 cm ^{3 of} methanol with the addition of 16 cm ^{3 of} concentrated chloroacetic acid and this solution is refluxed for 2 hours. After removing the methanol, the residue is distilled in vacuo. This gives 797 g (based on tetrachlorobutanol acetate, the yield is 94%) of 2,4,4,4-tetrachlorobutanol with a boiling point of 74 ° C./0.5 mm and a refractive index n ² ä = 1.5068. Elemental analysis: found C 24.10%, H 3.10%, 0 8.71%, Cl 64.49% (calculated C 22.7%, H 2.86%, O 7.56%, CI 66.9 %).

Step 3: water is added gradually with cooling to about O ⁰ C and continuous stirring 250 g (2.5 mol) of chromic anhydride dissolved in a mixture of 1250 ^cm-3 of glacial acetic acid and 250 cm ³ of water, to a solution of 200 g (0, 94MoI) tetrachlorobutanol in 500 cm ^{3 of} glacial acetic acid and the reaction mixture is then left to stand for 24 hours at room temperature. An equal volume of water is then added, the aqueous solution is extracted with ether and the ethereal solution is then extracted with an aqueous solution of sodium bicarbonate. The tetrachlorobutyric acid is isolated by acidifying the aqueous alkaline solution and extracting it again with ether. After removing the ether, the residue is distilled in vacuo.

This gives 110 g (52% based on tetrachlorobutanol) of 2,4,4,4-tetrachlorobutyric acid with a boiling point of 105 to 109 ° C./0.05 mm and a refractive index rf§ = 1.4980. Elemental analysis: found C 21.98%, H 2.10%, 0 14.09%, Cl 61.93% (calculated C 21.2%, H2.20%, O 14.10%, Cl 62.5% ). S.

Claims (7)

PATENT CLAIMS: 1. A process for the preparation of 2,4,4,4-tetrachlorobutyric acid, characterized in that carbon tetrachloride with allyl acetate in the presence of a radical-forming catalyst to 2,4,4,4-tetrachlorobutanol acetate and this by alcoholysis in 2,4,4, 4-Tetrachlorobutanol transferred, which is oxidized with chromic acid to 2,4,4,4-tetrachlorobutyric acid. 2. The method according to claim 1, characterized in that in the first stage of the process slowly brings the reactants into contact with one another. 3. The method according to claim 1 and 2, characterized in that in the first stage as Catalyst 1 to 10 parts by weight of an organic or inorganic per compound per 100 parts by weight Allyl acetate or ultraviolet light is used. 4. The method according to claim 1 to 3, characterized in that in the first stage 1 to 10 moles of carbon tetrachloride are used per mole of allyl acetate. 5. The method according to claim 1, characterized in that the alcoholysis of the second Stage with 5 to 20 moles of alcohol per mole of tetrachlorobutanol acetate, preferably methyl, ethyl or Isopropyl alcohol, and in the presence of 0.001 to 0.1 moles of hydrochloric acid, sulfuric acid or phosphoric acid per mole of tetrachlorobutanol acetate is carried out, initially with normal and then with moderately elevated temperature works. 6. The method according to claim 1, characterized in that the oxidation of the third stage with a solution of chromic anhydride in acetic acid containing 5 to 30% water. 7. The method according to claim 1 and 6, characterized in that the oxidation with a Carries out excess of 25 to 100% chromic anhydride. Considered publications:
"Journal of Chemical Society", London,
by 2038. 1954, © 109 619/431 6.