CA1188321A - Process for making acetic anhydride and/or acetic acid and/or ethylidene diacetate - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE
The disclosure relates to a process for making acetic anhydride and/or acetic acid and/or ethylidene diacetate by reacting methyl acetate and/or dimethylether with carbon mon-oxide or mixtures of carbon monoxide and hydrogen at tempe-ratures of 50 to 300°C, under reaction pressures of 1 to 500 bars and in the presence of a catalyst system. The disclo-sure provides more particularly for the catalyst system to consist of rhenium or its compounds; an organohalogen com-pound, halogen or hydrogen halide; further carbonyl-yielding common metals or their compounds, if desired; tertiary or quaternary organic nitrogen, phosphorus arsenic or antimony compounds, if desired; and alkali metal acetate or alkali metal compounds which undergo conversion to alkali metal ace-tate under the reaction conditions, if desired.

Description

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The invention relates to a process for making acetic anhydride and/or acetic acid and/or ethylidene diacetate by reacting me~hyl acatate and/or dimethylether with carbon mon-oxide or mixtures of carbon monoxide and hydrogen at tempe-ratures of 50 to }00C, under reaction pressure of 1 to 500 bars in the presence of a catalyst system as disclosed9 e.g in DE~OS 24 50 965; 28 36 084; 29 39 8~9 or 29 41 232.
The most rslevant component in such catalyst systam is selected from noble metals belo~ging to group ~IIIl ol the Periodic System, preferably rhodium, palladium~ iridium or ruthenium, or their compounds We have now unexpectedly ~.ound that rhenium can be sub-stituted ~or these very ex~e~sive noble metals.
The process of this lnvention comprises ~ors ~articu-larly: using, as the catal~st system, rhenium or l~s com-pounds; an org~ohalogen compound,halogen or 'nydrogen halide;
~urther carbonyl-yielding common metals or their compounds, iL
desired; a tertiary or quaternary orgarlic nitrogen, phosphorus, arsenic or antimon7 compound,if desired; and alkali met~l ace-tate or alkali metal. compounds which undergo conversion toalkali metal acetate under the reaction conditions, i~ desired.
The further carbonyl-yislding common metals comprise more particularly Cr, Mo, W9 Fe, Co or Ni.
Further preferred and optional features of the invention provide:
a) for the catalyst system to be used in combination with orga~ic nitrogen or phosphorus compounds quaternized wlth methyl halide or hydrogen halide;

b) for methyl acetate or dimethyl ther/rhenium(-compound)/
halogen(-compound)/nitrogen, phosphorus, arsenic or an-timony compound/alkali metal compound to be used in the molar ratio of 1 : (0.0001 - 0.1) : (0.01 ~ (0 - 1) :
(0 - 0.1).
~henium compounds useful in the process o~ this invention are, ~or example 9 rheniu~ chloride, rhenium oxychlorid0 or ~i-rheniumdecacarbonyl~
The in~entio~ provides ~or the halogen to be used in ele-mentary ~orm as chlori~e, bromine, iodine or in the ~orm of a halogen compound, pre~erably me~hyl chloride, methyl bromide, ~ethyl iodide, HCl, H3r, HI It is also possible however to se other alkyl halides and acyl halides inasmuch as the ~eed materials are not very critical.
The tertiary or quaternary organic nitrogen, phosphorus, arsenio or antimony compol~ds which may optionall~ be used ~i~e complexes with rhenium. The useful tertiary organonitro-~en or organophosphorus compounds comprise amines, phosphines or aminophosphines, pre~erably trialkylamines, N,N-dialkyl-anil~ne, pyridine, pyrrolidone, trialkyl or triarylphosphines, especially N-methylimida20le, 3-picoline, 2,4-lutidine, 3,4-lu-tidine, quinoline, tributylphosphine, trioctylphosphine, tri-laurylphosphi~e or triph~nylphosphine. It is also possible to use organonitrogen or organophcsphorus compounds quater~
nized with methyl halide or hydrogen halide, e g in the form o~ N-methylpyridinium halide, N,N-dime~thylimidazollum ~
halide, N-methyl-3-picolinium halide~ N-methyl-2,4-lutidinium halide, N-methyl-~,4-lutidinium halide, N-methyl-quinoli~ium halide, tributyl-methylphosphonium halide, trioctyl-methyl-phosphonium hzlide, trilauryl-methylphosphonium halide, tri 3~

phenyl-methylphosphonium halide, the halide being in each case chloride, bromide or iodide. The useful organic arsenic and antimolly compounds preferably lnclude arsines and stibines.
Acetates of potassium, rubidium or cesium should preferably be used as alkali metal compounds.
The composition of the feed gases may vary between 100 volume %
C0 and 20 volume % C0 + ~0 volume % H2j it is preferable however to use C0 and l-l2 in a ratio by volume of 90 : lO to 50 : 50.
The reaction should preferably be effected at temperatures of 120 to 250C and under pressures of 10 to 300 bars.
The reaction is carried out in an autoclave made up of corrosion-p:roof material, e.g. stainless steel or enameled steel over a period of l to 10 hours. It is also possible for it to be effected within shorter periods of time which permit the reaction to be effected continuously in a tlow reactor.
Example l 250 g methyl acetate, 50 g methyl ioclide, 60 g N,N-dimethyl-imidazolium iodide and 2 g dirheniumdecacarbonyl ~Re2(~0)10) were placed in a corrosionproof stainless steel reactor having a capacity of 1 liter.
After introduction of ~0 bars C0 and 20 bars hydrogen, the autoclave was heated to 200C. A maximum pressure of 150 bars was found to establish.
After a sojourn time of about 100 minutes under reaction conditions, the pressure in the autoclave dropped to 70 bars. The whole was worked up distillatively and 126.6 g acetic anhydride, 32.5 g ethylidene diacetate and 54.2 g ace-~3 33~

tic acid were obtained.
Example 2 ~he autoclave was fed with a mixture of 250 g methyl acetate, 50 g N-methylimidazole, 50 g methyl iodide, 50 g methyl chloride and 1.5 g Re2(C0)10. After introduction o~
90 bars C0 and 20 bars H2 and establishment of the reaction temperature of 210C, a ~ressure of 175 bars was ~ound to prevail inside the autoclave. A~ter a reaction period o~
1 hour, it was ~ound to ha~e dropped to 70 bars. The reac-tion mixture was worked up distillatively. 135 g acetic anhydride, 28 g ethylldene diacetate and 32 g acetic acid were obtained together with unchanged methyl iodide and unreacted methyl acetata.
Example 3 The rssidue obtained a~ter distillative wor!~ up as described in Example ~ was admixed with 250 g methyl acetate and 50 ~ methyl iodide, and used again as catal~s-t, C0-pres-sure = 80 bars; H2-pressuro = 20 'oars. At a reaction tempe-rature of Z00C the pressure inside the autoclave dropped within 30 minutes ~rom 150 to 65 bars. Next9 a ~urther 150 bars C0 was introduced until C0 ceased to be taken up. A~ter altogether 100 minutes, the reaction was terminated. The whole was wor~ed up distillatively and 290 g acet~c anhydride, 5.5 g ethylidene diacetate and Lo g acetic acid were obtained together with unchanged methyl iodide. Methyl acetate was detectable in traces only, Example 4 Feed materials used: 250 g methyl acetate g methyl iodide 1.5 g Re2(C0)10 The autoclave was scavenged with argon and 20 bars H2 and 80 bars C0 were introduced thereinto, At a temperature OL 200C, the pressure inside the autoclave dropped within

2 hours from 160 to 70 bars. 118 g acetic anhydride, 23 g ethylidene diacetate and 12 g acetic acid were obtained.
Example 5 Feed materials used: 250 g methyl aceta~e g methyl iodide g cesium acetate 1-5 g Re2(C)10 C0-~ressure = 80 ~ars; ~2-prossure = 25 bars at 20C. A re-action temperature of 205C was established. A~ter a reac-tion period o~ 2.5 hours the pressure insid~ the autoclave dropped ~rom 160 bars (maximum) to ~0 barst u~der the reac-tion conditions. The material wa~ distillatively separ~ted and 102 g acetic a~hydride, 25 g acetic acid and 28.8 g ethylidane diacetate were obtained togsther with unreacted meth~l acetate.
Example 6 Feed materials used: 250 g me~hyl acetate 50 g methyl iodide 1-5 g Re2(C)10 1C g methyl-tributylphos-phonium iodide 80 bars C0 and 20 bars H2 were introduced at 20C. At a reaction temperature of 205C, the pressure inside the autoclave increased up to 180 bars. A~ter 1.5 hours the re-action was ter~ïnated. 167.7 g acetic anhydride, 1.5 g ethy-lidene diacetate and 34 g acetic acid were o'otained from the

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reaction product Example 7 The residue which was obtained after distillative work up as described in Example 4 was removed from the distilling flask, taken up in aqua regia and ooncentrated to dryness.
Next it was aomixed with 250 g methyl acetate, 50 g methyl iodide and lO g N~N-dimethylimidazolium iodide and used as catalyst. C0-pressure = 85 bars at 20C; H2-pressure = 20 bars ~t 20C. At a reaction temper~ture of 210~C, the reactio~ pres-13 sure inside the autoclave dropped within 110 minutes to 70 bars.
197.7 g acetic ar~ydride, 17 g ethylidene diacetate and3~ g acetic acid wero obtained Example 8 The residue obtained a~ter distillative work up as des-cribed in Example 5 was treated as described in Example ~, 250 g methyl ~cetate, 50 g methyl :iodide and 10 g N,M-di--methylimidazolil!m iodide were added, 100 bars C0 (wit~out hydrogen) were introduced and the whole was heated to 210C.
20 ~he ~ressure inside the autoclave increased up ta 185 bars.
After 3.5 hours, the pressure wa~ ~ound to have dropped to 70 bars. Distillative work up yielded 246.7 g acetic an-hydride and 20 g acetic acid~
Example 9 250 g methyl acetate, 100 g mèthyl bromide, 30 ~ N-methyl-imidazole and 1.5 g Re2(C0)1~ were placed in the autoclave.
This latter was scavenged with argon and 80 bars C0 and 20 bars H~ were introduced thereinto. At a temperature of 215C
the pressure dropped within 6 hours from 180 bars to 90 bars.

After cooling and distillative work up 9 70 g acetic anhy-dride and 46 g acetic acid were obtained. ~thylidene di acetate could not be found to have been ~ormed in this Example.
Example 10 Feed materials used: 25Q g methyl acetate1 50 g methyl iodide, 60 g N~N-dimeth~limidazolium iodide, 1,5 g Re2(C0)10, 1 g I2, 80 bars C0, 20 bars ~2~
The autoclave was heated to 220C and the pressure dropped within 130 minutes from 165 to 70 bars. The reaction product wa~ worX@d u~ distillativel~J and founcl to contain 122 ~ acetic anhydride, 4~ g acetic acid and 12 ~ ethyli-dene diacetate.
Example 11 250 g methyl acetate, 50 g methyl iodide, 60 g N~N-di-methylimidazolium iod~de, 1.7 g ReCl5 and 0,87 g rhenium me-tal were placed in ~he autoclave. 80 bars C0 and 20 bars H2 wer~ int~oduced. 135 g acetic anhydride and 20 ~ acetic acid were obtained after a reaction period of 3 hours a~ 185~C.
Ethylidene diacetats could ~ot be found to have been formed.
Example 12 A mixture of 250 g methyl acetate, 50 g methyl iodide, 60 g mathyl-tributylphospho~ium iodide and 1.5 g Re~(CO)10 was placed in the autoclave. Next, 80 bars C0 and 20 bars H2 were introduced. 155 g acetic anhydride/ 23 g acetic acid and 6 g ethylidene diacetate were obtained within 5 hours at a reaction ter~perature of 215 to 2~0C.

Claims (3)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

WE CLAIM

1. A process for making acetic anhydride and/or acetic acid and/or ethylidene diacetate by reacting methyl acetate and/or dimethylether with carbon monoxide or mixtures of carbon monoxide and hydrogen at temperatures of 50 to 300°C, under reaction pressures of 1 to 500 bars and in the presence of a catalyst system, which comprises: using, as the catalyst system, rhenium or its compounds; an or-ganohalogen compound, halogen or hydrogen halide; further carbonyl-yielding common metals or their compounds, if desired; tertiary or quaternary organic nitrogen, phos-phorus, arsenic or antimony compounds, if desired; and alkali metal acetate or alkali metal compounds which under-go conversion to alkali metal acetate under the reaction conditions, is desired.

2. A process as claimed in claim 1, wherein the catalyst system is used in combination with organic nitrogen or phosphorus compounds quaternized with methyl halide or hydrogen halide.

3. A process as claimed in claim 1, wherein methyl acetate or dimethylether/rhenium(-compound)/halogen(-compound)/
nitrogen, phosphorus, arsenic or antimony compound/al-kali metal compound are used in the molar ratio of 1 :
(0.0001 - 0.1) : (0.01 - 1) : (0 - 1) : (0 - 0.1).