CA1152528A - Process for the preparation of acetoacetic acid alkyl esters - Google Patents
Process for the preparation of acetoacetic acid alkyl estersInfo
- Publication number
- CA1152528A CA1152528A CA000380711A CA380711A CA1152528A CA 1152528 A CA1152528 A CA 1152528A CA 000380711 A CA000380711 A CA 000380711A CA 380711 A CA380711 A CA 380711A CA 1152528 A CA1152528 A CA 1152528A
- Authority
- CA
- Canada
- Prior art keywords
- ester
- acid alkyl
- alkenyl
- alcohol
- acetoacetic acid
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
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Classifications
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C69/00—Esters of carboxylic acids; Esters of carbonic or haloformic acids
- C07C69/66—Esters of carboxylic acids having esterified carboxylic groups bound to acyclic carbon atoms and having any of the groups OH, O—metal, —CHO, keto, ether, acyloxy, groups, groups, or in the acid moiety
- C07C69/67—Esters of carboxylic acids having esterified carboxylic groups bound to acyclic carbon atoms and having any of the groups OH, O—metal, —CHO, keto, ether, acyloxy, groups, groups, or in the acid moiety of saturated acids
- C07C69/716—Esters of keto-carboxylic acids or aldehydo-carboxylic acids
- C07C69/72—Acetoacetic acid esters
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- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
- Low-Molecular Organic Synthesis Reactions Using Catalysts (AREA)
Abstract
Abstract:
Process for the preparation of acetoacetic acid alkyl esters Acetoacetic acid alkyl esters are prepared according to the invention by reaction of 2-acetoxy-crotonic acid alkyl esters or 2-acetoxyvinylacetic acid alkyl esters or a mixture thereof on the one hand and an aliphatic alcohol with 1 to 5 carbon atoms on the other hand. The reaction is carried out in the liquid phase at 50 to 250°C, the alcohol being employed in at least equimolar quantity.
Process for the preparation of acetoacetic acid alkyl esters Acetoacetic acid alkyl esters are prepared according to the invention by reaction of 2-acetoxy-crotonic acid alkyl esters or 2-acetoxyvinylacetic acid alkyl esters or a mixture thereof on the one hand and an aliphatic alcohol with 1 to 5 carbon atoms on the other hand. The reaction is carried out in the liquid phase at 50 to 250°C, the alcohol being employed in at least equimolar quantity.
Description
~5~8 The industrial preparation of acetoacetic acid alkyl esters is carried out today, in general, by reaction of diketene with the corresponding anhydrous aliphatic alcohol. In this reaction, a crude product is ob-tained which contains several low-boiling, middle-boiling and high-boiling compounds, apart from the des1red aceto-ac_tic acid alkyl ester. Above all, excess alcohol, ace-~one and alkyl acetate are contained in the crude ester as low-boiling compounds. In general, dehydroacetic acid and a thermally little stable residue, which is formed from diketene, are present as high-boiling compounds.
Mainly 3-acetoxy-crotonic acid alkyl or alkenyl esters, that is, ir.-the Ci9 form and the trans form, and 3-acetoxyvinylacetic acid alkyl or alkenyl esters occur as middle-boiling c ~ ounds which boil in the range of the corresponding acetoacetic acid alkyl ester. ~he pure acetoacetic acid alkyl ester is obtained from th s complex mixture by fractional distil-lation.
Whilst the low-boiling compounds and the high-boiling compounds may be separa~ed off without difficulty, this operation in the case of the middle-boiling compounds 3-acetoxycrotonic acid alkyl or alkenyl ester and 3-acetoxyvinyl-a^etic acid alkyl or alkenyl ester - mostly referred to as AC-ester or AV-ester in the following text - is not straight-forward. A separation of these components by fractionaldistillation is troublesome and is successful only with .
~ J~ i .. - I
" ~ "
.. .
~5~528 a high re ~u~ ratio, In ~heory, a simpler possibility would be a specific chemical conversion o~ these interfering sub-stances into o~her compounds more easily separable by distillation. Ho~ever, it had to be taken into con-sideration, in this case, that the-acetoacetic acid alkyl ester present as the main component o~ the mixture contains three reactive groups - a carbonyl group, a carbalkoxy group and an active methylene grcup - ard is there~ore very reactive. A chemical conversio~ of the interfering components AC-esier and AV-ester without simultaneous undesired reaction of the acetoacetic acid alkyl ester did not therefore appear possible.
Surprisingly, it has now been found that, by action of an alcohol on AC- and/or AV-ester, a smooth conversion o~ these com~ounds to acetoacetic acid alkyl ester takes place, without this compound itself reac~ing with the alcohol.
The pLocess according to the invention Ior the preparation of acetoacetic acid alkyl ester comprises the reactior. in the liouid phase at a tem~eratu~e of 50 to 250C o 3-aceiox~rcrotonic acid alkyl or alkenyl ester or 3-acetoxyvinylacetic acid alkyl or alkenyl ester or a mixture thereof ~rith an aliphatic alcohol w~ich cor.tains 1 to 5 carbon atoms, the alcohol being employed in at least eauimolar auartity.
The alkyl groups n the 3-acetoxycrotonic acid alkyl or alkenyl ester and in the 3-acetoxyvinylacetic acid aIkyl.or alkenyl ester preferably have 1 to 5 C atoms ar.d can be saturated 1~ ..
25;~8 or unsaturated, straight-chain or branched In the ~eaction of the AC-ester or of the AV-ester with the alcohol, ~he acetic acid ester of the alcohol e~ployed, that is the alkyl aceta~e already men-.. .. . . . . . . . . .. .. . . . . . . . . .
tioned above as the low-boiling compound, is formed in ... . . . .
addition to the acetoacetic acid alkyl ester.
AC-ester or AV-ester can be employed individually or mixed.
The two esters can be obtained individually or as a mixture lrom the crude product ~ihich is formed in the preparation of acetoacetic acid alkyl esters from diketene and an alcohol by ~irs~ separating off ~e low-boiling compounds and the high-boiling compounds and then .. . . . . ....... . .
isolating AC-ester, AV-ester and acetoacetic acid alkyl ester by fractional disi-llation. In this manner, AC-ester and AV-ester or a mixture thereof are obtained, free from acetoacetic acid alkyl ester.
Preferably, however, this relatively troublesome complete separation of the acetoacetic acid alkyl ester is not carried out, but the follo~ring procQdure is folloThTed: firstly, the 1ow-boi1ing compounds and the high-boiling compo~nds ar~ again separated olf by distillation f~om the crude product mentioned and the ~ain fraction containing the acetoacetic acid alkyl ester, the AC-es-ter ~5 an~ the AV-ester is then separated in a second distilla-tion into pure acetoacetic acid alkyl ester as the top product and into a mixture Gf acetoacetic acid alkyl ester/AC-ester/AV-ester as the ~ottom product This mixture is then reacted according to ihe invention with ~- ' , ;
. . : :. .
an aliphatic alcohol at $0 to 250C, preferably at 140 to 180C, and under a pressure corresponding to the vapor pressure of the mixture. The resulting reaction mixture is worked up to acetoacetic acid alkyl ester by distillation.
It is, however, alsopossible- although this is, as a - rule, less favora~le - to react the main ~raction me~tioned, .. . ... . . . . . . ... ..
and obtained after separating off the low-boiling compounds .... . . . . ... . ..
and high-boiling compounds, directly according to the invention with an aliphatic alcohol, ænd only then is .. . .. . . .
:pure acetoacetic acid alkyl ester distilled off as the top .. . . . . . . . .. ...
- product and a bottom produci which contains the remaining acetoacetic acid alkyl ester and the unreacted AC- and AV-ester is obtained.
A corresponding procedure is of co~lrse foll~red with pure (that is,not containing acetoacetic acid alkyl ester) AC-ester or AV-ester or a mixture thereo~.
Appropriately, the alcohol which was employed in the preparation of the acetoacetic acid alkyl ester from diketene is used in the reaction of an AC-ester/AV-ester/
acetoacetic acid alkyl ester mixture obtained as men-tioned. In the preparation ol methyl acetoacetate this alcohol is methanol, for ethyl acetoacetate ethanol etc The AC-ester ~nd AV-ester components to be reacted have an alkoxy group which corresponds to the alcohol employed in the diketene reac~ion. Methyl acetoacetate there-fore contains acetoxycrotonic acid methyl ester and acetox-yvinylacetic acid methyl ester as acco~panying components; the homologous compounds behave correspondingl~.
Mainly 3-acetoxy-crotonic acid alkyl or alkenyl esters, that is, ir.-the Ci9 form and the trans form, and 3-acetoxyvinylacetic acid alkyl or alkenyl esters occur as middle-boiling c ~ ounds which boil in the range of the corresponding acetoacetic acid alkyl ester. ~he pure acetoacetic acid alkyl ester is obtained from th s complex mixture by fractional distil-lation.
Whilst the low-boiling compounds and the high-boiling compounds may be separa~ed off without difficulty, this operation in the case of the middle-boiling compounds 3-acetoxycrotonic acid alkyl or alkenyl ester and 3-acetoxyvinyl-a^etic acid alkyl or alkenyl ester - mostly referred to as AC-ester or AV-ester in the following text - is not straight-forward. A separation of these components by fractionaldistillation is troublesome and is successful only with .
~ J~ i .. - I
" ~ "
.. .
~5~528 a high re ~u~ ratio, In ~heory, a simpler possibility would be a specific chemical conversion o~ these interfering sub-stances into o~her compounds more easily separable by distillation. Ho~ever, it had to be taken into con-sideration, in this case, that the-acetoacetic acid alkyl ester present as the main component o~ the mixture contains three reactive groups - a carbonyl group, a carbalkoxy group and an active methylene grcup - ard is there~ore very reactive. A chemical conversio~ of the interfering components AC-esier and AV-ester without simultaneous undesired reaction of the acetoacetic acid alkyl ester did not therefore appear possible.
Surprisingly, it has now been found that, by action of an alcohol on AC- and/or AV-ester, a smooth conversion o~ these com~ounds to acetoacetic acid alkyl ester takes place, without this compound itself reac~ing with the alcohol.
The pLocess according to the invention Ior the preparation of acetoacetic acid alkyl ester comprises the reactior. in the liouid phase at a tem~eratu~e of 50 to 250C o 3-aceiox~rcrotonic acid alkyl or alkenyl ester or 3-acetoxyvinylacetic acid alkyl or alkenyl ester or a mixture thereof ~rith an aliphatic alcohol w~ich cor.tains 1 to 5 carbon atoms, the alcohol being employed in at least eauimolar auartity.
The alkyl groups n the 3-acetoxycrotonic acid alkyl or alkenyl ester and in the 3-acetoxyvinylacetic acid aIkyl.or alkenyl ester preferably have 1 to 5 C atoms ar.d can be saturated 1~ ..
25;~8 or unsaturated, straight-chain or branched In the ~eaction of the AC-ester or of the AV-ester with the alcohol, ~he acetic acid ester of the alcohol e~ployed, that is the alkyl aceta~e already men-.. .. . . . . . . . . .. .. . . . . . . . . .
tioned above as the low-boiling compound, is formed in ... . . . .
addition to the acetoacetic acid alkyl ester.
AC-ester or AV-ester can be employed individually or mixed.
The two esters can be obtained individually or as a mixture lrom the crude product ~ihich is formed in the preparation of acetoacetic acid alkyl esters from diketene and an alcohol by ~irs~ separating off ~e low-boiling compounds and the high-boiling compounds and then .. . . . . ....... . .
isolating AC-ester, AV-ester and acetoacetic acid alkyl ester by fractional disi-llation. In this manner, AC-ester and AV-ester or a mixture thereof are obtained, free from acetoacetic acid alkyl ester.
Preferably, however, this relatively troublesome complete separation of the acetoacetic acid alkyl ester is not carried out, but the follo~ring procQdure is folloThTed: firstly, the 1ow-boi1ing compounds and the high-boiling compo~nds ar~ again separated olf by distillation f~om the crude product mentioned and the ~ain fraction containing the acetoacetic acid alkyl ester, the AC-es-ter ~5 an~ the AV-ester is then separated in a second distilla-tion into pure acetoacetic acid alkyl ester as the top product and into a mixture Gf acetoacetic acid alkyl ester/AC-ester/AV-ester as the ~ottom product This mixture is then reacted according to ihe invention with ~- ' , ;
. . : :. .
an aliphatic alcohol at $0 to 250C, preferably at 140 to 180C, and under a pressure corresponding to the vapor pressure of the mixture. The resulting reaction mixture is worked up to acetoacetic acid alkyl ester by distillation.
It is, however, alsopossible- although this is, as a - rule, less favora~le - to react the main ~raction me~tioned, .. . ... . . . . . . ... ..
and obtained after separating off the low-boiling compounds .... . . . . ... . ..
and high-boiling compounds, directly according to the invention with an aliphatic alcohol, ænd only then is .. . .. . . .
:pure acetoacetic acid alkyl ester distilled off as the top .. . . . . . . . .. ...
- product and a bottom produci which contains the remaining acetoacetic acid alkyl ester and the unreacted AC- and AV-ester is obtained.
A corresponding procedure is of co~lrse foll~red with pure (that is,not containing acetoacetic acid alkyl ester) AC-ester or AV-ester or a mixture thereo~.
Appropriately, the alcohol which was employed in the preparation of the acetoacetic acid alkyl ester from diketene is used in the reaction of an AC-ester/AV-ester/
acetoacetic acid alkyl ester mixture obtained as men-tioned. In the preparation ol methyl acetoacetate this alcohol is methanol, for ethyl acetoacetate ethanol etc The AC-ester ~nd AV-ester components to be reacted have an alkoxy group which corresponds to the alcohol employed in the diketene reac~ion. Methyl acetoacetate there-fore contains acetoxycrotonic acid methyl ester and acetox-yvinylacetic acid methyl ester as acco~panying components; the homologous compounds behave correspondingl~.
2 52 8 Basic21ly, ho~rever~ an alcohol which does not correspond to the carbalkoxy group of these esters may also be used for the reaction of the AC-ester and the AV-ester.
Thus, for example, acetoxycrotonic acid methyl ester and -acetoxyvinylacetic acid methyl ~ester may be directly reacted ~ th butanol.
A reaction time of fro~ 4 to 6 hours has proved to be the most favorable. In this time, an extensive conversion takes place. This amounts to 65 to 95%
under the c~nditions i~dicated. After reaction has taken place, the reaction mixture is worked up, prefer-ably together wi~h the crude product formed in the reac-tion of diketene with an alcohol, and a complete conver-sion of the AC-ester and the AV-ester is therefore not required in the process according to the invention and is even inexpedient for reasons o~ cost efficiency.
The ~lorkirg-up of the crude product mantionedg resulting from the reaction of diketene with an alcohol, is thus simplified b~j coupling with the process according to the inven~ion: after the separation o~ the high-.. . . . . . .. . . .. ..
boiling compounds and low-boiling compounds from th~ crude _ . . . . . .. . . . . ........................ .. ..
product, onl~ the main portion of ~he acetoace~ic acid alkyl ester is distilled off (instead of distilling it off as far a~ possible, as hitherto~ and the remaining portion, togelher with AC- and A~-esters, is employed in the process according to the invention For the process a~ccording to the invention, a mixture which contains as high a portion as possible of AC- and AV-esters is preferably employed Such a .:
~ - ~
:~.5;~5;~8 mix~ure is obtained from ihe bottom of the column in which the distillation for the purification of the aceto-acetic acid alkyl ester, after separation of the high_ ..
boiling compounds and low-boilin~ compcunds, is carried out. The concentration o~ acetoacetic acid alkyl ester is, in this case, between 20 and 80% by weight, preferably 40 to 50% by weight. However, even in the case of substantially higher va~ues, the reaction pro-ceeds without difficulties Basically, all aliphatic alcohols ~'nich co-ntain 1 to 5 carbon atoms a~e suitable as t'he alcohol component in ~he process according io t~e invention. The carbon chain can be straight-chain or branched and the alconol can be a primary, secordary or tertiary alcohol; further, 1~ unsaturated alcohols can also be used Thus, for example, the follo~ing alcohols may be used as reaction partners: methanol, ethanol, propan-1-ol, propan-2-ol, butan-1-ol, butan-2-ol, 2-methyl-propan-1-ol, 2-me~hyl~
propan-2-ol, pentan-l-ol, pentan-2-ol, pen-tan-~-ol, 2-methyl-butan-4-ol, 2-methyl-butan-3-ol, 2-methylbu~an-2-ol, 2-methylbutan-1-ol, 2,2-dimethyl-propan-1-ol and prop-l-en-3-ol. Primary alcohols are preferred~ in particular me~hanol and ethanol.
The two follcwing embodiments ol -the prccess according to the i~vention are particularly favorable:
.. . ... . . . . . . . . . . .. . ..
- 'a) High-boiling compounds and low-boiling compcunds _ . . . ~ ...... . . ....... .. . .. . . ... . .
and subseauently the main portion of the methyl aceto-acetate are separated off from the crude product ~Jhich has formed in the contin~ous preparation of methyl ~ 2 52 8 acetoacetate fro~ diketene and methanol 3-Acetoxy-crotonic acid methyl ester, 3-acetox~-vinylacetic acid methyl ester and the remainder of the methyl acetoacetate is obtained as the botiom product. This bottom pro-duct is reacted with methanol according to the inventionto give methyl acetoacetate-. The product obtained in this reaction is co~bined with the crude product men-tioned above (from the con~inuous reaction of diketene and methanol to give methyl acetoacetate) and is w~orked up ~rith this crude product to give pure methyl aceto-acetate.
b) Hlgh-bolling compounds and low-bolllng compounds _ . _ . _ . .. . . ..... . ... .. . . _ . _ ... . .. . .. . . .. _ . .
- ænd subsequently the ~in portion of the ethyl aceto-acetate are separaied off from the cLude produc~ w~ich 15 has formed in ~he con~inuous preparation of ethyl ;
acetoacetate ~rom diketene and ethanol. 3-Acetoxy-crotonic acid e~hyl ester, 3-acetoxyvinylacetic acid ethyl ester and the remairLder of the ethyl acetoacetate areobiained as the bo~tom product. This bottom pro-duct is reacted ~i'h ethanol according to the invention to give ethyl acetoacetate. The product obtained in this reaction is combined ~.ith the crude ~roduct ~en-tioned above (from the continuous reac~ion of diketene and ethanol to give ethyl acetoacetate) and is worked u~ with this crude product to give pure ethyl aceto-- - acetate.
The followin~ examples illustrate the process according to the inNen~ion:
.~'' ' ' ' .
:
52~i2~
_ 9 _ .
- Exam~le 1 50 g of a mLxture of the fol'owing composition were employed: 53.07' by ~igh~ of methanol, 45 ~ by weight of 3-acetoxycrotonic acid methyl ester (cis- and - 5 trans-forms) and 3-acetoxyviny:Lacetic acid methyl ester, 0.60~' by weight of methyl acetoaceiate and 0.5% by ~reight of other middle- and high-boiling compounds. ~his mix-_ . . _ . . . . . . . . ........... . . . .. . .. . ture was heated in an autoclave to 170C for 6 hours~
-a pressure of 11.3 oars being established at the end of the reaction. The reaction mixture ~as again - analy7ed a er it had cooled do~m, g~ving the following composition: 67.2 ~ by weight of low-boiling compounds . _ . _ . . . .. . . .. ... . . . . .. . . _ . . . ...
(for the most par~ methyl acet~te and m~thanol), 31.4%
by weight of methyl acetoacetate, 1 4% by ~eight of ace~ox-ycrotQnic acid meth-yl ester and acetoxyvinylacetic acid methyl ester and 0.29S by ~reight of other middle-... . ... . . _ .. . .. ..
and high-boiling compo~ds.
... . . . . .. . .. . . . ~
Example 2 50 g of a mixture of the follo~g composition ~Jere employed: 53.6~/c by ~eight of methanol, 25.0% by weight of methyl acetoacetate and 2l.4ob by ~Jeight of 3-- acetoxycrotonic acid methyl ester ~cis and trans) and ~acetoxyvinylacetic acid methyl ester. This mixture ~las heated in an autoclave to 170C for 6 hours, a pres-2~ sure of 10.8 bars being established at the end of the reaction. A sample of ~he reaction mixtl~re ~ad ~he - followi~ composition aft~er it had cooled down: 57.~b _ . , . . . ... .. . . , . .. . . . . . . . _ _ ..... . . . . ... _ .
by weight of low-boiling com~ounds (for the most part .... . .
methyl acetate and methanol), 35.7% by w~ight o~ methyl .~'' ' ' .
, ;2S28 acetoacetate, 6.1% by weight of 3-acetoxycrotonic acid methyl ester and 3-acetoxyvinylacetic acid methyl ester and 0.3% by ~reight of other middle-and high-boiling . .
- compounds.
.. . . . ... _ .~
~ _xGm~le 3 50 g of a mixture of the ~ollowdng composition - were employed: 51.3% by weight of ethanol, o.goh by ~leight of ethyl acetoaceta~e, 47 5% by weight of 3-acetoxycroton-- ic acid ethyl ester (cis and trans) and 3-acetoxyvinyl-acetic acid ethyl ester, and 0.3% by weight of other middle- and high-boiling compounds. This mixture was .. .. . . . ..
heated in an autoclave to 170C for 6 hours, a pressure of 10.1 bars being esta~lished at the end of the reac- .
tion. The reaction mixture had the follo~ing compo-sition after it h~d cooled down: 67 0% by ~reight of lo~r-.. . . .. . . . . .. . . .. ...
boiling compo~mds (for the most part ethyl acetate and ethanol), 30.5% by ~reight of ethyl acetoacetate, 1~9% by ~;eight of 3-acetoxycrotonic acid ethyl ester and 3-ace~oxyvinylacetic acid ethyl ester9 and 0.6q~ by ~rei~ht of other middle- and high-boiling compounds.
_, _ . . .. . . . _ Exæm~le 4 10~ g of a mixture of the follo~ing composition ere employed: 44.~ by weight of ethanol, 25.7% by weight o~ ethyl acetoacetate, 30.1% by weight of 3-acetoxycrotonic acid ethyl ester (cis and trans) and 3-acetoxyvinylacetic acid ethyl ester, and O.~,S by ~Jeight . . .
o~ other middle- and high~boiling co pounds. ~his mi~-- ture ~ias heated in an autocl~ve to 170C lor 6 hours, a pressure of 9.7 bars being established at the end ~1 . .
~, .
~.
- . . .
of the reaction. A sample of reaction mlxture had the following compos~tion after it ha~ cooled do~Jn 53.1 % by weight of low-boiling compounds (for the most part ethyl acetate and ethanol), ~5.4% by weight o~ ethyl acetoacetate, 10.6~' by weight of 3-acetoxycrotonic acid ethyl ester and 3-acetox~rvinylacetic acid ethyl ester, and 0.9% by ~Jeight of other middle- and high~boiling compounds.
... . . . .
.~ '- ' , .:
: , ~ .
Thus, for example, acetoxycrotonic acid methyl ester and -acetoxyvinylacetic acid methyl ~ester may be directly reacted ~ th butanol.
A reaction time of fro~ 4 to 6 hours has proved to be the most favorable. In this time, an extensive conversion takes place. This amounts to 65 to 95%
under the c~nditions i~dicated. After reaction has taken place, the reaction mixture is worked up, prefer-ably together wi~h the crude product formed in the reac-tion of diketene with an alcohol, and a complete conver-sion of the AC-ester and the AV-ester is therefore not required in the process according to the invention and is even inexpedient for reasons o~ cost efficiency.
The ~lorkirg-up of the crude product mantionedg resulting from the reaction of diketene with an alcohol, is thus simplified b~j coupling with the process according to the inven~ion: after the separation o~ the high-.. . . . . . .. . . .. ..
boiling compounds and low-boiling compounds from th~ crude _ . . . . . .. . . . . ........................ .. ..
product, onl~ the main portion of ~he acetoace~ic acid alkyl ester is distilled off (instead of distilling it off as far a~ possible, as hitherto~ and the remaining portion, togelher with AC- and A~-esters, is employed in the process according to the invention For the process a~ccording to the invention, a mixture which contains as high a portion as possible of AC- and AV-esters is preferably employed Such a .:
~ - ~
:~.5;~5;~8 mix~ure is obtained from ihe bottom of the column in which the distillation for the purification of the aceto-acetic acid alkyl ester, after separation of the high_ ..
boiling compounds and low-boilin~ compcunds, is carried out. The concentration o~ acetoacetic acid alkyl ester is, in this case, between 20 and 80% by weight, preferably 40 to 50% by weight. However, even in the case of substantially higher va~ues, the reaction pro-ceeds without difficulties Basically, all aliphatic alcohols ~'nich co-ntain 1 to 5 carbon atoms a~e suitable as t'he alcohol component in ~he process according io t~e invention. The carbon chain can be straight-chain or branched and the alconol can be a primary, secordary or tertiary alcohol; further, 1~ unsaturated alcohols can also be used Thus, for example, the follo~ing alcohols may be used as reaction partners: methanol, ethanol, propan-1-ol, propan-2-ol, butan-1-ol, butan-2-ol, 2-methyl-propan-1-ol, 2-me~hyl~
propan-2-ol, pentan-l-ol, pentan-2-ol, pen-tan-~-ol, 2-methyl-butan-4-ol, 2-methyl-butan-3-ol, 2-methylbu~an-2-ol, 2-methylbutan-1-ol, 2,2-dimethyl-propan-1-ol and prop-l-en-3-ol. Primary alcohols are preferred~ in particular me~hanol and ethanol.
The two follcwing embodiments ol -the prccess according to the i~vention are particularly favorable:
.. . ... . . . . . . . . . . .. . ..
- 'a) High-boiling compounds and low-boiling compcunds _ . . . ~ ...... . . ....... .. . .. . . ... . .
and subseauently the main portion of the methyl aceto-acetate are separated off from the crude product ~Jhich has formed in the contin~ous preparation of methyl ~ 2 52 8 acetoacetate fro~ diketene and methanol 3-Acetoxy-crotonic acid methyl ester, 3-acetox~-vinylacetic acid methyl ester and the remainder of the methyl acetoacetate is obtained as the botiom product. This bottom pro-duct is reacted with methanol according to the inventionto give methyl acetoacetate-. The product obtained in this reaction is co~bined with the crude product men-tioned above (from the con~inuous reaction of diketene and methanol to give methyl acetoacetate) and is w~orked up ~rith this crude product to give pure methyl aceto-acetate.
b) Hlgh-bolling compounds and low-bolllng compounds _ . _ . _ . .. . . ..... . ... .. . . _ . _ ... . .. . .. . . .. _ . .
- ænd subsequently the ~in portion of the ethyl aceto-acetate are separaied off from the cLude produc~ w~ich 15 has formed in ~he con~inuous preparation of ethyl ;
acetoacetate ~rom diketene and ethanol. 3-Acetoxy-crotonic acid e~hyl ester, 3-acetoxyvinylacetic acid ethyl ester and the remairLder of the ethyl acetoacetate areobiained as the bo~tom product. This bottom pro-duct is reacted ~i'h ethanol according to the invention to give ethyl acetoacetate. The product obtained in this reaction is combined ~.ith the crude ~roduct ~en-tioned above (from the continuous reac~ion of diketene and ethanol to give ethyl acetoacetate) and is worked u~ with this crude product to give pure ethyl aceto-- - acetate.
The followin~ examples illustrate the process according to the inNen~ion:
.~'' ' ' ' .
:
52~i2~
_ 9 _ .
- Exam~le 1 50 g of a mLxture of the fol'owing composition were employed: 53.07' by ~igh~ of methanol, 45 ~ by weight of 3-acetoxycrotonic acid methyl ester (cis- and - 5 trans-forms) and 3-acetoxyviny:Lacetic acid methyl ester, 0.60~' by weight of methyl acetoaceiate and 0.5% by ~reight of other middle- and high-boiling compounds. ~his mix-_ . . _ . . . . . . . . ........... . . . .. . .. . ture was heated in an autoclave to 170C for 6 hours~
-a pressure of 11.3 oars being established at the end of the reaction. The reaction mixture ~as again - analy7ed a er it had cooled do~m, g~ving the following composition: 67.2 ~ by weight of low-boiling compounds . _ . _ . . . .. . . .. ... . . . . .. . . _ . . . ...
(for the most par~ methyl acet~te and m~thanol), 31.4%
by weight of methyl acetoacetate, 1 4% by ~eight of ace~ox-ycrotQnic acid meth-yl ester and acetoxyvinylacetic acid methyl ester and 0.29S by ~reight of other middle-... . ... . . _ .. . .. ..
and high-boiling compo~ds.
... . . . . .. . .. . . . ~
Example 2 50 g of a mixture of the follo~g composition ~Jere employed: 53.6~/c by ~eight of methanol, 25.0% by weight of methyl acetoacetate and 2l.4ob by ~Jeight of 3-- acetoxycrotonic acid methyl ester ~cis and trans) and ~acetoxyvinylacetic acid methyl ester. This mixture ~las heated in an autoclave to 170C for 6 hours, a pres-2~ sure of 10.8 bars being established at the end of the reaction. A sample of ~he reaction mixtl~re ~ad ~he - followi~ composition aft~er it had cooled down: 57.~b _ . , . . . ... .. . . , . .. . . . . . . . _ _ ..... . . . . ... _ .
by weight of low-boiling com~ounds (for the most part .... . .
methyl acetate and methanol), 35.7% by w~ight o~ methyl .~'' ' ' .
, ;2S28 acetoacetate, 6.1% by weight of 3-acetoxycrotonic acid methyl ester and 3-acetoxyvinylacetic acid methyl ester and 0.3% by ~reight of other middle-and high-boiling . .
- compounds.
.. . . . ... _ .~
~ _xGm~le 3 50 g of a mixture of the ~ollowdng composition - were employed: 51.3% by weight of ethanol, o.goh by ~leight of ethyl acetoaceta~e, 47 5% by weight of 3-acetoxycroton-- ic acid ethyl ester (cis and trans) and 3-acetoxyvinyl-acetic acid ethyl ester, and 0.3% by weight of other middle- and high-boiling compounds. This mixture was .. .. . . . ..
heated in an autoclave to 170C for 6 hours, a pressure of 10.1 bars being esta~lished at the end of the reac- .
tion. The reaction mixture had the follo~ing compo-sition after it h~d cooled down: 67 0% by ~reight of lo~r-.. . . .. . . . . .. . . .. ...
boiling compo~mds (for the most part ethyl acetate and ethanol), 30.5% by ~reight of ethyl acetoacetate, 1~9% by ~;eight of 3-acetoxycrotonic acid ethyl ester and 3-ace~oxyvinylacetic acid ethyl ester9 and 0.6q~ by ~rei~ht of other middle- and high-boiling compounds.
_, _ . . .. . . . _ Exæm~le 4 10~ g of a mixture of the follo~ing composition ere employed: 44.~ by weight of ethanol, 25.7% by weight o~ ethyl acetoacetate, 30.1% by weight of 3-acetoxycrotonic acid ethyl ester (cis and trans) and 3-acetoxyvinylacetic acid ethyl ester, and O.~,S by ~Jeight . . .
o~ other middle- and high~boiling co pounds. ~his mi~-- ture ~ias heated in an autocl~ve to 170C lor 6 hours, a pressure of 9.7 bars being established at the end ~1 . .
~, .
~.
- . . .
of the reaction. A sample of reaction mlxture had the following compos~tion after it ha~ cooled do~Jn 53.1 % by weight of low-boiling compounds (for the most part ethyl acetate and ethanol), ~5.4% by weight o~ ethyl acetoacetate, 10.6~' by weight of 3-acetoxycrotonic acid ethyl ester and 3-acetox~rvinylacetic acid ethyl ester, and 0.9% by ~Jeight of other middle- and high~boiling compounds.
... . . . .
.~ '- ' , .:
: , ~ .
Claims (7)
OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A process for the preparation of an acetoacetic acid alkyl ester in which a 3-acetoxycrotonic acid alkyl or alkenyl ester, a 3-acetoxyvinylacetic acid alkyl or alkenyl ester or a mixture thereof is reacted in the liquid phase at a temperature of from 50 to 250°C with an aliphatic alcohol which contains 1 to 5 carbon atoms, the alcohol being employed in an at least equimolar quantity.
2. A process as claimed in claim 1 in which the alkyl or alkenyl groups of the 3-acetoxycrotonic acid alkyl or alkenyl ester, or the 3-acetocyvinylacetic acid alkyl or alkenyl ester are straight-chain or branched and contained 1 to 5 carbon atoms.
3. A process as claimed in claim 1 in which the alcohol contains the same alkyl or alkenyl group as the 3-acetoxycrotonic acid alkyl or alkenyl ester or the 3-acetoxyvinylacetic acid alkyl or alkenyl ester.
4. A process as claimed in claim 1, claim 2 or claim 3 in which a primary aliphatic alcohol is employed.
5. A process as claimed in claim 1, claim 2 or claim 3 in which methanol or ethanol is employed as the aliphatic alcohol.
6. A process as claimed in claim 1, claim or claim 3 in which 3-acetoxycrotonic acid alkyl or alkenyl ester and 3-acetoxyvinylacetic acid alkyl or alkenyl ester are employed in mixtures with an acetoacetic acid alkyl or alkenyl ester, all three esters having the same alkyl or alkenyl group and the portion of the acetoacetic acid alkyl or alkenyl ester in the mixture being 40 to 50% by weight.
7. A process as claimed in claim 1, claim 2 or claim 3 in which a reaction is carried out at a temperature of from 100 to 200° C.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE19803024535 DE3024535A1 (en) | 1980-06-28 | 1980-06-28 | METHOD FOR THE PRODUCTION OF ACETIC ACID ALKYL ESTERS |
| DEP3024535.3 | 1980-06-28 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1152528A true CA1152528A (en) | 1983-08-23 |
Family
ID=6105883
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000380711A Expired CA1152528A (en) | 1980-06-28 | 1981-06-26 | Process for the preparation of acetoacetic acid alkyl esters |
Country Status (4)
| Country | Link |
|---|---|
| EP (1) | EP0043088B1 (en) |
| JP (1) | JPS5738748A (en) |
| CA (1) | CA1152528A (en) |
| DE (2) | DE3024535A1 (en) |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2900311A (en) * | 1952-10-11 | 1959-08-18 | Union Carbide Corp | Purification of acetoacetic esters by distillation |
-
1980
- 1980-06-28 DE DE19803024535 patent/DE3024535A1/en not_active Withdrawn
-
1981
- 1981-06-23 DE DE8181104851T patent/DE3161956D1/en not_active Expired
- 1981-06-23 EP EP81104851A patent/EP0043088B1/en not_active Expired
- 1981-06-26 JP JP9845281A patent/JPS5738748A/en active Granted
- 1981-06-26 CA CA000380711A patent/CA1152528A/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| EP0043088A1 (en) | 1982-01-06 |
| DE3024535A1 (en) | 1982-01-28 |
| EP0043088B1 (en) | 1984-01-18 |
| DE3161956D1 (en) | 1984-02-23 |
| JPH0251891B2 (en) | 1990-11-08 |
| JPS5738748A (en) | 1982-03-03 |
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