DE2406058B1 - Process for the preparation of allyl esters - Google Patents

Description

ORIGINAL

If yield losses occur, it has proven to be expedient to carry out the rearrangement only so far that part of the starting products is implemented. The mixture thus obtained is then separated, e.g. B. by fractional distillation, and unreacted starting material returned to the reaction zone. The reaction is preferably carried out in such a way that 10 to 60%, in particular 20 to 50%, of starting materials be relocated to the desired end products. The residence times during the relocation are based according to temperature, carboxylic acid and catalyst concentration. It can last from a few minutes to several Hours. Dwell times of 10 to 120 minutes are preferably observed.

The catalyst is either filtered off during work-up, or the possibly dissolved catalyst is obtained as a residue in the work-up by distillation and is used again for the rearrangement.

The allyl esters obtained by the process of the invention are suitable for the production of allyl alcohols, z. B. vinyl glycol, and for the production of /? - formyl crotylate, an intermediate for the synthesis of vitamin A (US Pat. No. 3,732,287).

The following examples illustrate the process. The parts by weight are related to the Divisions of volume as grams to milliliters.

example 1

In a high-pressure autoclave with a volume of 800 parts by volume, 250 parts of butene-2-diol-1,4-diacetate, 250 parts of glacial acetic acid and 2.5 parts of copper (I) oxide are mixed. The autoclave is heated very quickly to 180 ^° C. and this temperature is kept constant for 30 minutes. It is then cooled again very quickly to room temperature. In the distillative working up of 481.6 parts of the reaction mixture are 162.1 parts of a first fraction of Kp. _3o 42 to 52 ⁰ C, 245.8 parts of Fraction 2, bp. ₀₃ = 48-106 ⁰ C, 68 parts cold trap content and 5.7 parts of solid residue were obtained. According to the gas chromatographic analysis, the cold trap contents and fraction 1 consist almost exclusively of acetic acid. In addition to small amounts of acetic acid, fraction 2 mainly contains butene-1-diol-3,4-diacetate, cis-butene-2-diol-1,4-diacetate and trans-butene-2-diol-1,4-diacetate . The evaluation of the analysis shows that with a conversion of 26.4% of the butene-2-diol-1,4-diacetate used, butene-1-diol-3,4-diacetate was formed in 93.2% selectivity.

Example 2

As described in Example 1, 250 parts by volume of butene-2-diol-1,4-diacetate, 250 parts of glacial acetic acid and 2.5 parts of copper (I) oxide are ^{heated to 180 °} C. for 1 hour.

When 499 parts of the reaction mixture are worked up, 9 parts of residue and 273.3 parts are obtained Parts of a main fraction which, in addition to small amounts of acetic acid, mainly butene-l-diol-3,4-diacetate, ice-cream and trans-butene-2-diol-1,4-diacetate. The conversion of 2-butene-1,4-diacetate is 32% and the yield of butene-1-diol-3,4-diacetate, based on the converted starting material, is 86.2% of theory.

B is ρ ie 1 3 ^6s

As described in the preceding examples, 250 parts of butene-2-diol-1,4-diacetate, 250 parts of glacial acetic acid and 25.4 parts of copper (II) acetate are ^{heated to 180 °} C. for 1 hour and then worked up by distillation. 17 parts of residue and 250 parts of the main fraction are obtained from 496 parts of reaction mixture. The conversion of butene-2-diol-1,4-diacetate is 30.7%, the selectivity 83.5% of butene-1-diol-3,4-diacetate.

Example 4

As described in Examples 1 to 3, 250 parts of butene-2-diol-1,4-diacetate and 250 parts of glacial acetic acid are used and 10 parts cupric oxide heated at 200 ° C for 0.5 hour. Working up 486 parts of the reaction mixture gives 236 parts of the main fraction and 9 parts Residue. The analysis of the main fraction gives a conversion of 46.5% butene-2-diol-1,4-diacetate and a selectivity for butene-1-diol-3,4-diacetate of 81.1%.

Example 5

As described in the previous examples, 225 parts of butene-2-diol-1,4-diacetate, 25 parts of glacial acetic acid and 1.25 parts of copper (I) oxide are allowed to react ^{at 190 ° C. for 30 minutes.} 245.3 parts of the main fraction are obtained. The conversion of butene-2-diol-1,4-diacetate is 13.9% in this experiment, the selectivity for butene-1-diol-3,4-diacetate is calculated to be 63.2%.

Comparative example 1

As described above, 250 parts Bute.n-2-diol-l, 4-diacetate and 12.7 parts K upfer (II) -acetatl reacted hour at 180 ⁰ C. Working up the (filtered) reaction mixture (238.4 parts) gives 5.2 parts of residue and 224.8 parts of the main fraction. The GC analysis shows that 5.3% of butene-2-diol-1,4-diacetate have reacted. The selectivity of the reaction is 46% of theory.

Comparative example 2

The procedure is as in the previous example with the difference that only 1.3 parts of copper (II) acetate are used as Catalyst starts. In this case, the degree of conversion of the butene-2-diol-1,4-diacetate used is only about 4%.

Comparative example 3

As described in the previous examples, 250 parts of butene-2-diol-1,4-diacetate and 1.25 parts of copper (I) oxide are used For 0.5 hours at 200 ° C. In the work-up, 239.9 parts of reaction mixture are used 236.4 parts of main fraction, 0.8 parts of cold trap contents and 1.8 parts of residue were obtained. The degree of conversion of butene-2-diol-1,4-diacetate is 2.4%.

The comparative examples show that poorer results are obtained without the use of carboxylic acids will.

Example 6

As in the preceding examples, 100 parts of butene-2-diol-1,4-diacetate, 400 parts of glacial acetic acid and 10 parts of copper (I) oxide are ^{heated to 200 °} C. for 1 hour. Working up 484 parts of the reaction mixture gives 99 parts of the main fraction and 6 parts of residue. The analysis shows that 50.7% of the butene-2-diol-1,4-diacetate used have been converted and that butene-1-diol-3,4-diacetate is formed with 61.7 percent selectivity.

Claims (1)

1 2 fer (II) compounds as catalysts and in counter- Claim: wart of carboxylic acids. The new method has the advantage that it is with Process for the preparation of allyl esters of good yields and, moreover, none Formula 5 elaborate precious metal catalysts that are quantitative CJJ ₂ _ qjj. . Qfj R ₁ must be recovered, are also used I (I) den. OCOR In the preferred starting materials of formula II ² R ₁ denotes an alkyl group with 1 to 2 carbon in which R _{1 stands} for an alkyl group with 1 to 4 carbon atoms, which has an acyloxy group with up to 3 carbon substance atoms that can have an acyloxy group with up to lenstoffatomen as substituents, while May have 4 carbon atoms as substituents, R _{2 stands} for an alkyl radical with 1 to 4 carbon atoms and R _{2 is} an alkyl radical having 1 to 4 carbon. The atoms or a hydrogen atom,. Esters of butene-2-diol-1,4-with fatty acids with 1 to obtained by isomerization of allyl esters of the formula 15 4 carbon atoms. Suitable starting materials are for example butene-2-l, 4-diol diacetate or H ₂ C CH = CH R ₁ butene-2-diol-1,4-diformate or dipropionate. Special I (Π) whose technical importance has butene- (2) -diol- (l, 4) - OCOR ₂ diacetate obtained. 20 The isomerization is generally from Tempe Rain which R ₁ and R ₂ as defined above doors of 100 to 300 ⁰ C. Particularly comfortable, at elevated temperature in the presence of sustains temperatures of 150 to 250 ⁰ C. Catalysts, characterized thereby- It is possible to carry out the isomerization under Atmärenn that the isomerization is carried out in the presence of pressure to a suitable high temperature of metallic copper and / or copper (I) - 25 ren, however, it is expedient to use increased and / or copper (II) compounds as catalyst pressure. In general, it is sufficient to carry out the gates and in the presence of carboxylic acids by isomerization in closed devices, the vapor pressure of the agents used being established. This is usually between 30 see 1 and 20 atmospheres, depending on the applied Temperature. The isomerization is carried out with the use of It is known that allyl esters are carried out with acidic carboxylic acid catalysts. Isomerize preferred carboxylic acids. It is also known that allyl acids with 1 to 4 carbon atoms such as ameiesters can be rearranged under the catalytic influence of metals, acetic acid, propionic acid or butyric acids, or metal compounds. So is z. B. It is particularly preferred to use that carbon from German Auslegeschrift 2134 115, acid which is also contained in the allyl ester of the formula II that is butene-2-diol-1,4-diacetate under the catalyst. If you z. B. of butene-2-diol-1,4-acetate has the influence of palladium or platinum compounds, acetic acid is expediently used. gene can rearrange to butene-l-diol-3,4-diacetate. The processes mentioned above are advantageously kept in the reaction mixture, but have the disadvantage that the concentration of carboxylic acids of 10 to 90 percent by weight is used when very expensive noble metal compounds are used. Carbon had to be particularly cheap. As a result, even low acid concentrations of 30 to 80% have been proven
ste losses of noble metals must be avoided- The isomerization is in the presence of copper, which is technically very expensive. 45 metal and / or copper (I) - and / or copper (II) -Ver-A process for the production of bonds as catalysts has now been carried out. Preferred allyl esters of the formula copper compounds are, for example, copper (I) - oxide, cupric oxide, or copper salts with strong CH ₂ = CH CH - R ₁ mineral acids or fatty acids such as copper (I) chloride, I (I) 50 copper (II) chloride, copper (II) acetate, copper (II) sul- OCOR ₂ fat or copper (II) nitrate. Copper (I) oxide and copper (II) acetate are of particular technical importance in which R _{1 represents} an alkyl group having 1 to 4 carbon. The catalytically active copper compounds Atoms that can have an acyloxy group with up to 4 carbon atoms or copper themselves can be as such or on can have lenstoffatomen as substituents, and R ₂ 55 carriers such as aluminum oxide, pumice stone or silica gel an alkyl radical having 1 to 4 carbon atoms or a can be used. It is advantageous to use the Denotes hydrogen atom, by isomerization of said copper catalysts in amounts from 0.01 to Allyl esters of the formula 10 percent by weight, in particular from 0.1 to 1 percent by weight, based on the allyl ester used, H ₂ C - CH = CH - R ₁ 60 calculated as metal. I (Jl) The isomerization can be discontinuous OCOR ₂ can be carried out continuously in one or more reaction stages. If you have more than one reaction in which R ₁ and R _{2 have} the meaning given above, they are consecutively referred to as ben switched at elevated temperature in the presence of Kata- 65 cascade. For example one uses found lysers, which is characterized in that advantageously 2 to 4 series-connected reaction that the isomerization in the presence of metal stages. Since the relocation with increasing displacement ic copper and / or copper (I) - and / or cupola time, the formation of residues increases and thereby