DE2062522A1 - - Google Patents

Description

Patent attorneys 8 Munich 2, BrauhauMtraße 4 / IH

SC 5647/5787

RHONE-POULENC S.A., Paris / France

Process for the preparation of aldehydes by the oxidation of

chloromethylated derivatives

The present invention relates to a process for the preparation of aldehydes by oxidation of chemical compounds which Have rthlormethylated groups in the vapor phase.

It is already known that certain compounds with chloromethyl groups can be converted into compounds with aldehyde groups by oxidation of the chloromethyl group. For example, P. Shorigin and I. Kizberg (Chemical Abstract 25, 5680 ⁸⁾ benzaldehyde from chloromethyl benzene by oxidation with air over a catalyst based on vanadium have produced, this reaction was carried out at a temperature of 400-480 ⁰ C. Besides that. it is known that at such temperatures one can also oxidize a methyl group bonded to an ethylenic carbon atom (for example propylene, which leads to acrolein, French patent specification 1 580 882) or an alkyl group bonded directly to an aromatic ring (for example toluene or isopropylbenzene, American «Patent 5,260,751 ).

The oxidation of a compound which has chloromethylated groups and other oxidizable groups in its molecule, for example a methyl group, generally leads to a mixture of compounds that consists of the partial or full

109128 Π 54 «

constant oxidation of the chloromethyl groups and / or methyl * groups results.

The present invention relates to a process for the preparation of aldehydes of the general formula YCHOi in which the Symbol Y is a radical from the group consisting of the alkylphenyl radicals and the alkenyl radicals of the general formula

C = C -

means in which the symbols Rm, Rp and R, hydrogen atoms ™. or represent alkyl radicals, where at least one of these symbols represents a methyl radical, by treating a compound of the formula YGHgCl in the vapor phase with oxygen, which is characterized in that in the presence of ^vo1 * derivatives of element ender groups IB, HIA, IHB, IVA, IVB, VA, VB and VIB of the Periodic Table of the Elements (as stated in the Bulletin de la Soeiete Chimique de France, January 1966) or iron works.

This process enables the To oxidize chloromethyl residues to residues -CHO, the constituents of the remainder Y remain practically unchanged.

In the chloroethylated products of the formula YCHpCl can the various straight-chain or branched alkyl radicals 1 to 6 carbon atoms · In addition, the alkylphenyl radicals have one, two or more alkyl radicals.

As. Examples of the compounds of the formula YCHgGIi include the following: Methallyl chloride, 4-chlorobutene- (2) =, 2-methy; 1-4-chlorobutene- (2), 3-methyl-4-chlorobutene- (2) , ^ Μβ ^ Ι - ^ -. ΟΙιΙαΡρθ »*«! - (3), ^ -Methyl-S-ethyl-e-chlorhexen- (4), Q ~ _t w * and ρ-ΟΙιΙοΓωβί ^ ΙΙϊοΙϊίοΙίί m- and p -Chlomethylcumene,

^ 2-methyl-4-butylchlorIaethyl- ·

BATH ORIGINAL

The metal or metalloid derivatives used in the process according to the invention, which serve to catalyze the desired reaction, can be free metals, which are optionally activated *, metal oxides or metalloid oxides or mixtures of these oxides in which some of the various oxides are in the form of salts of inorganic acids or Heteropolyacids can be combined. If metal oxides are used, these can be chosen from those of copper, iron, tin, lead, titanium, zirconium, vanadium or potassium. Among the metalloid oxides one can mention those of boron, phosphorus, silicon and germanium. Among the combinations of oxides, for example, lead or thallium stannates and zirconates can be mentioned. The oxides can be applied to an inert carrier or to a carrier with which they can be combined in part in the form of salts of inorganic acids. These derivatives are, for example, in the general articles relating to the ammonia xydai, ion reaction Russian Chemical Reviews 34. (9) ⁶ 57 (1965)? Chemische Technik 20 (10) 600-609 (1963J7).

The procedure for preparing these derivatives is described in French patents 1,161,138, 1,171,975, 1,333,040, 1,365,889, as well as in British Patent Specification 904,602.

A practical implementation of the invention is to pass the mixture of the reaction compounds in the gaseous state over the catalyst in Pestbett, which is preferably maintained at 350 to 450 ⁰ C at a temperature of 300 to 600 ⁰ C,. The gas mixture is preheated to a temperature of 100 to 150 ⁰ C, before it reaches the catalyst.

Theoretically, the composition of the mixture should be 0.5 molecules of oxygen per chloromethyl group to be oxidized. In the Practice uses an excess of oxygen that is up to can be more than ten times the theoretical amount. the end Reasons for the self-elimination of such mixtures if the oxygen is diluted with an inert gas,!

109826/1548

For example, steam or nitrogen as a diluent ^:

use. This is the reason why the air is oxidized proves to be particularly advantageous. In this latter. .-. One can trap in the presence of an excess of air ,, .the _ 12 to 15 times the required theoretical air volume. can amount to work. In general, the throughput is adjusted so that the contact time with the catalyst is 0.5 to 8 seconds and is preferably 1 to 3 seconds. The products leaving the apparatus are then cooled very quickly to avoid side reactions to avoid. The aldehyde compounds can by any conventional method, for example by fractionated Distillation or by removing the aldehyde in the form its bisulfite compound. ,

The following examples serve to further illustrate the invention.

example 1

In a tubular reaction vessel with an inner diameter

3
of 1 cm is brought in 10 cm of a catalyst which was prepared according to the procedure described in French Patent 1,161,138 by impregnating aluminum oxide with a specific surface area below 5 m / g with a vanadyl oxalate solution with a concentration such that after drying and Galinating the percentage of vanadium oxide deposited reaches 5%. A mixture of air, o-chloromethyltoluene and steam (volume ratio, measured under normal-pressure-temperature conditions: 78: 1: 1) is passed onto the ^{catalytic bed heated to 400 ° C. in an amount of 3.6 liters per hour.} . The effluents are recovered by passing in a trap containing 200 cm ⁵ cooled to -20 ⁰ C chloroform. After ten hours of reaction, the chloroform solution is analyzed by chromatography. The analysis shows that no o-chloromethyltoluene remained and that the yield of o-methylbenzaldehyde is £ 70. First the chloroform is removed by distillation and Hg pure aldehyde is then obtained »

109826/1948

Example 2

This example is carried out according to the procedure described in Example 1 with the same catalyst, replacing the o-chloromethyltoluene with the corresponding m-derivative. The temperature is 425 ⁰ C. It is using the same throughput, and the same molar ratios found that the degree of conversion is the m-Chlormethyltoluols $ 98, while the yield is 79 ° i.

Example 3

This experiment is carried out like that of Example 2, the only change being that the m-chloromethyltoluene is replaced by p-chloromethyltoluene.

It is found that the degree of conversion is 94 $ and the yield of p-methylbenzaldehyde, based on the reagents, is 56 $ . "

Example 4

The m-chloromethyltolubl from Example 2 is replaced by p-isopropylchloromethylbenzene. The other parameters are identical. It is found that the degree of conversion of the p-isopropylchloromethylbenzene is $ 93, while the yield based on the reagents is $ 78. The same experiment is carried out at 375 ⁰ C. It is then found that the degree of conversion is only 41 #, while the yield is $ 30>.

Example 5

• 5

500 mg of the catalyst of the preceding example are introduced into a 0.5 cm reaction vessel and a gas stream of 0.9 liters per hour (normal pressure temperature) consisting of 1 part is introduced into the catalyst bed heated ^{to 400 °} C. Methallyl chloride and 9 parts of air . The reaction effluents are analyzed by gas phase chromatography. One finds a complete conversion of Methallylchlorids and conversion to methacrolein of 78 $. "

109826/1948

BATH ORIGINAL

Example 6

The catalyst of Example 5 is replaced by 500 mg of a catalyst based on iron and antimony oxide, which is prepared according to the procedure described in French Patent 1,333,040. The other reaction parameters remain the same. It is observed by chromatography in that the degree Encrypt lungs 89 f "and the yield based on the reagents, $ 57 is.

Example 7

The catalyst of Example 5 is replaced by 500 mg of a catalyst based on tin oxide and antimony oxide, which is prepared according to the procedure described in British patent specification 864 666, the other reaction parameters remaining identical. It is found by chromatography that the degree of conversion is 95 ° and the yield, based on the reagents, is 50 % .

Example 8

The catalyst of Example 5 is replaced by 500 mg of a catalyst based on copper oxide and silica, which is prepared according to the procedure described in British Patent 674,860. The chromatographic analysis shows that the degree of conversion of the methallyl chloride is quantitative and the yield is 59 ° .

109826/1948.

Claims (1)

Patent entitlement Process for the preparation of aldehydes of the general formula YGHO, in which the symbol Y is a radical from the group consisting of the alkylphenyl radicals and the alkenyl radicals of the general formula T ¹ -
\ j - means in which the symbols R ^, R ₂ and R- represent hydrogen atoms or alkyl radicals, at least one of these symbols representing a methyl radical, by treating compounds of the formula YCHpCl in the vapor phase with oxygen, characterized in that in the presence of derivatives of elements of groups IB, IIIA, IHB, IVA, IVB, VA, VB and VIB of the periodic table of the elements or of iron works- 109826/19 * 8