DE2851371B1 - Process for the production of ketones - Google Patents

Description

The process is suitable for the production of all possible ketones. The only requirement is that the starting carboxylic acid halides do not contain any further have functional groups which with Al-alkylene or alkyl-Al-halides can react in an undesirable manner. Otherwise the carboxylic acid halides be aliphatic, aromatic, araliphatic or heterocyclic in nature and both have one or more acid halide groups. Preferred carboxylic acid halides are those which are encompassed by the general formula R'COX, in which Rl = a) a saturated or unsaturated, branched or unbranched aliphatic Remainder, preferably with 4 to 20, in particular with 4 to 8 carbon atoms:

b) an optionally mono- or polysubstituted aryl, preferably Phenyl radical; if the aryl or phenyl radical is substituted, this is preferably the case 1 or 2 times, mainly through C1 -C4 alkyl radicals - especially CH3 -, Halogen, in particular Cl, Br, -NO2, COOR '(R' = C1-C4-alkyl, preferably CH3), sulfamoyl SO2NH2 or SO2NR "R" '(R "and R"' = organic residues) etc.

c) an aralkyl radical, the aromatic part of which is preferably a phenyl radical and can be substituted one or more times in the same way as the one below b) said aryl radical, and its aliphatic part preferably has 1-3 carbon atoms, or d) a heterocyclic - preferably 0- and / or S-containing heterocyclic - radical, in particular furyl or thiophenyl radical, and X = halogen (Cl, Br, I), preferably Cl. -As specific starting carboxylic acid halides are mentioned in an exemplary manner: n-butyryl chloride n-octadecanoic acid chloride 3,3-dimethylacrylic acid chloride benzoyl chloride o-chlorobenzoyl chloride p-chlorobenzoyl chloride 3. chloro-5-methylbenzoyl chloride 2,6-dichlorobenzoyl chloride m-bromobenzoyl chloride p-bromobenzoyl chloride p-methylbenzoyl chloride p-tert-butyl benzoyl chloride p-nitrobenzoyl chloride p-carbomethoxybenzoyl chloride m-carbobutoxybenzoyl chloride phenylacetic acid chloride 4-chlorophenylacetic acid chloride cinnamic acid chloride 4-chlorocinnamic acid chloride furan-2-carboxylic acid chloride Thiophene-2-carboxylic acid chloride etc.

For the reaction with the carboxylic acid halides according to the invention Processes are Al-alkyls and alkyl-Al-halides of the general formula R2AIX3 "is used, where R2 = saturated branched or unbranched alkyl radical, preferably with 1 to 12, in particular with 1 to 3 carbon atoms; X = halogen (Cl, Br, I), preferably Cl and n = 1, 1.5, 2 or 3, preferably 1.5 (= Alsesqui halides).

Specific compounds falling under this formula are, for. B.

Methyl aluminum dichloride, methyl aluminum sesquichloride, dimethyl aluminum chloride, Trimethyl aluminum, Ethyl aluminum sesquichloride, ethyl aluminum sesqui-iodide, tri-n-propyl-aluminum, Tri-n-hexyl aluminum, n-hexyl aluminum dichloride, n-dodecyl aluminum dibromide etc.

If in the process in addition to the Al-alkylene or alkyl-Al-halides nor is an aluminum halide used, it is preferred to use an Al halide to use the same halogen radical as the alkyl-Al-halide. As alkyl-Al-halides Chlorides are preferred, AlCl3 is also preferred as aluminum halide.

The use of an aluminum halide in addition to each Al-alkyl or alkyl-Al-halide is done with the purpose of, if possible, all alkyl groups of the Al-alkyl or alkyl-Al halide for the reaction with the corresponding Take advantage of carboxylic acid halide. Form the ketones formed in the process namely rather stable complexes with the Al-alkylene and alkyl-Al-halides, whereby then the ethyl groups of the Al-organic compounds for further implementation with the Cai'boh'säur'ehalog'e'nid are no longer available. Because Al halides like AlCl3 are stronger Lewis acids than Al-alkyls and alkyl-Al-halides, they push them out of the complexes and therefore make them suitable for further implementation available with the carboxylic acid halides.

It is therefore preferred to use per equivalent of carboxylic acid halide (one equivalent of a carboxylic acid halide containing only one COX group 1 mol) a) about 1 Mole of alkyl-Al-dihalide R2AIX2 (and no Al-halide) b) about 1/2 mole of dialkyl-Al-halide -R22AIX + about 1/2 mole of Al halide c) about 2/3 moles of alkyl-Al-sesqüiJ + alogenid R²1.5AlX1.5 + about 1/3 mol of Al halide or d) about 1/3 mol of trialkyl-Al R23Al + about 2/3 mol of Al halide to use. It is cheap. when the Al-organic compound is about 5% Excess is used. Higher surpluses do not bring any advantage. The same in principle also applies - for the Al halide.

If the carboxylic acid halides have such substituents (e.g. Ketone groups), which form stable complexes with organic aluminum compounds, become so one equivalent of organic Al compound or of Al halide per substituent additionally required.

The process is expediently carried out in such a way that CH2Cl2 is initially introduced and therein the Al halide - if one is required - suspended.

Then, with careful exclusion of oxygen, the Approach calculated amount of Al-alkyl or alkyl-Al-halide added to this mixture the acid chloride is allowed to flow in so quickly that the onset of methylene chloride reflux can be easily kept under control. In this case, the reaction temperature is around 400C. After the addition of the acid chloride has ended, there will be a short time - generally about 1 hour - stirred.

If you let the acid chloride flow in more slowly, that's enough The heat generated by the exothermic reaction may not be sufficient to bring the CH2C12 to the boil to bring. In this case, the reaction temperature is then below about 40 "C in the range between room temperature (about 200 C) and about 40 ° C.

In some cases it can also be useful to carry out the reaction Temperatures above about 40 "C to carry out. It must then, however, under excess pressure be worked, the use of a closed vessel in which at the higher temperature the corresponding autogenous pressure adjusts itself automatically, makes sense. However, the most convenient way to carry out the process is generally that under normal pressure at the reflux temperature of CH2Cl2 (about 40 ° C).

After the reaction has ended, the reaction mixture is allowed to decompose the resulting ketone-Al-halide complexes are mixed with water, for which purpose the reaction mixture is added expediently can flow on water or ice. Because of the resulting heat The CH2Cl2 normally starts to boil here and can be distilled off or under Be held at reflux.

The reaction mixture treated with water then becomes the desired one Ketone in the usual way, e.g. e.g.

by distillation.

Ketones obtainable or obtained by the process are, for example: Hexanone-3 decanon-4 nonadecan-2-one mesityl oxide butyrophenone propiophenone o -chloroacetophenone o-chloropropiophenone m-chloroacetophenone 3-chloro-5-methylpropiophenone 2,6-dichloroacetophenone m-bromopropiophenone p-bromoacetophenone p-bromopropiophenone p-methylacetophenone p-methylpropiophenone p-tert-butyl-butyrophenone p-nitroacetophenone p-carbomethoxyacetophenone m-carbobutoxy-butyrophenone Phenylacetone 1-phenylbutanone-2 4-chlorophenylacetophenone 4-chlorobenzalacetone 2-acetylthiophene 2-acetylfuran etc.

The ketone yield in this process is consistently at least about exactly as high as the conventional procedure in which (in CH2Cl2) was only worked at temperatures around or - preferably - below 0 C. In some In some cases, economic yields can only be achieved at the higher reaction temperature can be achieved. This was based on the statements in the relevant section mentioned at the beginning Literature is in no way to be expected and, moreover, represents mainly because of the There is no need to cool the reaction mixture to or below 0 ° C to keep represents a very significant operational improvement. In detail, the reasons for the progress of the procedure are specified as follows be: a) By working at higher temperatures, especially in boiling methylene chloride At 40 "C without pressure or above at overpressure, complex cooling systems are avoided and evaporative cooling, which is extremely easy to control in terms of process technology, can be used be utilized by refluxing the solvent.

b) Inactive carboxylic acid chlorides can be used with the higher Implement the temperature in a shorter reaction time.

c) At the higher temperature there is hardly any risk of delays in the reaction to concentrations of unreacted which are questionable from a safety point of view Lead reactants.

The invention will now be explained in more detail by the following examples. Unless otherwise specified, all of the inventive examples were made according to the following Procedure carried out: CH2Cl2 was submitted and solid AlCl3 (anhydrous) suspended. The alkyl-Al or alkyl-Al halide was then added. In this mixture was allowed to flow in the respective carboxylic acid chloride so quickly that that the onset of CH2Cl2 reflux could be kept under control. To When the addition was complete, the mixture was subsequently stirred for 1 hour.

The reaction mixture was then allowed to flow onto water, with the exothermic decomposition reaction caused the methylene chloride to boil.

The batch was then worked up further by distillation if not stated otherwise, 0.3 mol of carboxylic acid chloride with 0.1 mol of AlCl3 and 0.21 mol of (CH3) r, 5AIClls or (C2HsjlsA1Clis in approx. 1 to 10 g of CM2Cl2 per g of carboxylic acid chloride implemented.

The comparative examples included in the following table in addition to the inventive examples were carried out in the same way, except that the reaction mixture was always kept at a temperature around or below 0 ° C. by external cooling. The results are compiled in a table. Starting Al-alkyl-Al. Temp. Reaction product yield Carboxylic acid or alkyl halide ketone (@ .d. Th.) halide Al halide A) aliphatic: CH3 (CH1) 1COCl (C2H3) 1AlCl3 AlCl2 approx. 40 ° C CH7 (CH2) 2COC2H 95% the same the same the same 0 ° C (compare) the same 95% the same (n-C5H18) AlCl3 the same approx. 40 ° C CH3 (CH2) 2COC6H13 88% (0.3 moles) CH3 CH3 # # C = CH-COCl (CH3) 15AlCl15 AlCl3 approx. 40 ° CC = CH-CO-CH3 94% # # CH3 CH3 the same the same the same 0 ° C (comp.) the same 93% B) aromatic: COCl # (CH3) 15AlCl15 AlCl3 approx. 40 ° C # -CO-CH3 97% # the same the same the same 0 ° C (compare) the same 82% the same (C2H5) 15AlCl15 the same approx. 40 ° C # -CO-C2H5 95% COCl # # #Cl (C2H5) 15AlCl1,5 AlCl3 approx. 40 ° C # -CO-CH3 98% # Cl the same the same the same 22-25 ° C the same 95% the same the same the same 60 C / 2 bar the same 96% the same the same the same 0 ° C (comp.) the same 94% the same the same the same approx. 40 C # -CO-C2H5 94% # Cl COCl # (CH3) 15AlCl15 AlCl3 approx. 40 ° C # -CO-CH2 96% # # #Cl Cl the same CH3AlCl2 - approx. 40 ° C the same 95% (0.3 moles) continuation Starting Al-alkyl-Al temp. Reaction product yield Carboxylic acid or alkyl halide ketone (% of theory) halide Al halide B) aromatic: COBr # -CO-CH3 # (CH3) 2AlBr AlBr @ approx. 40 C Cl 96% Cl (0.15 mol) COCl H3C # (C2H5) 1.5AlCl1.5 AlCl @ approx. 40 C # -CO-C2H5 91% CH3 Cl Cl COCl Cl Cl Cl # (CH3) 1.9AlCl2.5 AlCl @ approx. 40 C # -CO-CH @ 96% Cl COCl # (C2H5) 1.5AlCl1.5 AlCl @ approx. 40 C # -CO-C2H5 95% Br Br COCl # (CH3) 1.5AlCl1.5 AlCl @ approx. 40 C Br - # - CO-CH3 96% Br the same (C2H5) 1.5AlCl1.5 the same approx. 40 C Br - # - Co-C2H5 92% COCl # (CH3) 1.5AlCl1.5 AlCl @ approx. 40 C H3C - # - CO-CH3 98% CH3 the same. (C2H5) 1.5AlCl1.5 the same approx. 40 C H3C - # - CO-C2H5 95% continuation Starting Al-alkyl-Al temp. Reaction product yield Carboxylic acid or alkyl halide ketone (% of theory) halide Al halide B) aromatic: COCl # (CH3) 1.5AlCl1.5 AlCl @ approx. 40 C O2N - # - COCH3 41% NO2 COCl # (CH3) 1.5AlCl1.5 AlCl @ approx. 40 C H5C2OOC - # - CO-CH3 72% COOC2H5 (0.21 mol) (0.4 mol) C) araliphatic CH2COCl (CH3) 1.5AlCl1.5 AlCl @ approx. 40 C # -CH2-CO-CH3 86% # (C2H5) 1.5AlCl1.5 the same approx. 40 C # -CH2-CO-C2H5 84% same as DC (compare) same 80% CH2-COCl # (CH3) 1.5AlCl1.5 AlCl @ approx. 40 C Cl - # - CH2-CO-CH3 85% Cl CH = CH-COCl # (CH3) 1.5AlCl1.5 AlCl @ approx. 40 C Cl - # - CH = CHCOO-CH3 88% Cl D) heterocyclic: # (CH3) 1.5AlCl1.5 AlCl @ approx. 40 C # -CO-CH3 75% O (0.21 mole) (0.2-0.4 mole) O COCl same as DC (compare) same 0% # (CH3) 1.5AlCl1.5 AlCl @ approx. 40 C # -CO-CH3 88% S (0.21 moles) (0.2-0.4 moles) S. COCl same as DC (compare) same 15%

Claims (1)

Claim: Process for the production of ketones by conversion of carboxylic acid halides that have no other functional groups, which can react with Al-alkylene or alkyl-Al-halides in an undesirable manner, with Al-alkylene or alkyl-Al-halides, optionally in the presence of an Al-halide, in methylene chloride as solvent and decomposition of the resulting ketone complex in water, d ad u r c h e k e n n -z soft n e t that one can carry out the reaction in the temperature range from about 20 to about 40 "C under normal pressure and in the temperature range above to about 60 "C under autogenous (excess) pressure. Ketones are valuable intermediates and end products on numerous important ones Subjects, e.g. B. in the field of dyes, pesticides, the Pharmaceuticals and solvents etc. There are a number of classic methods for making ketones known. A newer method is based on carboxylic acid halides, which are combined with organoaluminum Compounds (Al-alkyls and alkyl-Al halides) converted to the respective ketones will. Benzene was initially used as the solvent for this reaction, in which the reaction was carried out at temperatures up to 80 "C. [J. Am. Chem. Soc. 73, 2854-56 (195011. For this method, the Ketone yields indicated, but it cannot be avoided here that as a result of the Catalytic action of the Al compounds used also Friedel-Crafts acylations of the solvent benzene, which of course results in not inconsiderable losses in yield enter and experience difficulties in separating and purifying the desired Ketones. To avoid Friedel-Crafts acylations of the solvent if the solvent benzene is replaced by aliphatic hydrocarbons (pentane, Hexane etc.) replaced [Fette-Seifen-Anstrichmittel 64, 881-86 (1961)]. The reaction temperature but should not be significantly higher than 0 C here, otherwise as a result of increased Formation of by-products should lower the yield of the desired ketone. When testing other, if possible even cheaper, solvents Finally, methylene chloride CH2Cl2 was found to be the “solvent of choice” [Tenside 4, 167-71 (1967); Organometalic Chemical Reviews A, S. & 7-136, in particular Pp. 55/56 (1968); Houben Weyl, Vol. VlI / 2a, 4th edition Ketones, Part 1, p. 573-575 (1973)]. This solvent possesses over the before aromatic and aliphatic hydrocarbons used as solvents the advantage that practically all reactants and end products are soluble in it. In this procedure, too, the reaction temperature should not be higher than approximately O "C - if possible, however, be below it - as several times in the relevant literature It is clearly emphasized - undesirable side reactions at temperatures above about 0 ° C ever increasing men and thus of course the yield of the desired ketones should continue to decrease. According to the relevant state of the art, there was - if one did not want to accept a considerable reduction in yield - a clear prejudice on the other hand, the well-known ketone synthesis from carboxylic acid halides and Al-organic Carry out connections in CH2Cl2 at temperatures above about 0 ° C. on the other hand but must in order to comply with the required low reaction temperatures the exothermic reaction requires a not inconsiderable amount of cooling. Because of the otherwise good course and the good yields as well as the possibility Using this method, produce ketones that are not or difficult to obtain in any other way To be able to do so, it was therefore desirable and the task still existed, the method to improve and to make it as economical as possible. According to the invention, this task could be achieved in a simpler and more excellent manner Way can be solved by the fact that the reaction in question at temperatures at which the heat dissipation can be carried out much more economically, d. H. in the range between about 20 and about 60 "C. Surprisingly occur the deteriorated yields predicted by the relevant literature (compared to the method of implementation at temperatures around or below 0 ° C) not - or at least not to a significant extent - a. In many cases it was even found a significant increase in yield. The invention thus has a clear one technical prejudice overcome and at the same time a well-known beneficial process made even more advantageous and economical. The subject of the invention is a process for the production of ketones by converting carboxylic acid halides that have no other functional groups have which react with Al-alkyl or alkyl-Al-halides in an undesirable manner can, with Al-alkylene or alkyl-Al-halides, optionally in the presence of a Aluminum halide, in CH2Cl2 as a solvent and decomposition of the resulting Ketone complex with water, which is characterized in that the reaction in the temperature range from about 20 to about 40 "C under normal pressure and above Performs temperature range up to about 60 "C under autogenous (over) pressure.