DE2019175A1 - Process for the production of butyl esters - Google Patents

Description

20t9175

Dit, iiro.r.wt7K * riiojnr -, - ■ '■ - ■ . ■ · .-: · "." ■■■ - ... «utrx cw ** #o ■■■ ;. ■ -.-.

dim * ing. σ, πγιλ ■ ^: ,, - ■■, ';"·Οιι" τχι "ιιιμτκαμκ"

i4

DBv IKO. D. BKHBBNS

1A-3?

BeBC hr β ibu η ^ to the patent application

Nippon Soda Company, Ltd, Shin ^ Ohtemaohi Building Ohtemachi, Chiyoda-Ku, (Tokyo /

"Process gup production of vöfl butyl esters"

■ Tert-butyl ester and butyl ester mixture, consisting of η-, selc, - and isobutyl ester "are separated and independent from each other in an economic way with good yields; from a best BB fraction (spent BB fraction) or G ^ fraction » which contains isoTautylenes and butenes, in two separate ones (one 2H | tU - ".>, .. Reactions produced, the first reaction being the one tert-butyl ester leads, below a temperature below 40 ° C and the second reaction, which gives a butyl ester mixture, at a temperature in the range between 60 and 120 ° C and is carried out under pressure. Under the remainder of the BB group one understands the remaining ^ unused praction after butadiene has been removed from a C ^ mixture, which is through thermal or catalytic cracking of a petroleum stream or by dehydration of C ^ paraffins or C ^ olefins, has been received.

The invention relates to a method for producing Butyl esters of organic acids and especially a process for the production of butyl esters from a residual BB praction or a similar starting material. :. ,

8A & OFIiGINAt.

2-1975

so?

Tert?, -Btttyl * eta £ and special ttrt * ~ sutyi * c6tate can be obtained by the reaction of awisschea tert-butyl alcohol and an acid anhydride such as esaige acid anhydride or ketene. This process is not really economical because it starts with expensive raw materials. Another common process for the discovery of tertiary butyl acetate consists in reacting acetic acid with pure isobutylene under pressure at relatively low temperatures in the presence of a suitable catalyst. There are many I ^ te ^ e in this field _; --un4-y ^ aehi »dfn ^^ A3 ^ eBv w» "| ^ taly8atii» ren.fiiid ^.

aue dei * O ^^ akii ^ dtci ^ iiit ^ voä eßleltliver. "

AAsorption separated and fewonnen weai ^ eii ima and that due this koaplissieyten separation process is proportional is expensive and whereby the manufacturing costs can not be significantly reduced. It was getting intense Investigations undertaken »for a, more economical process «Μ? Manufacture of te3Pt »-Butylestfti» su develop and this A new process has been developed that assumes a residual BB-Praction as raw material »The fiest BB-Fraktion remains as the remaining and unused fraction after Extracting butadiene from a C ^ gemiscti back that by thermal or catalytic cracking of a petroleum stream or by dehydration of CL paraffins or C 1-4 olefins · This residual BB fraction falls through the increasing induction of artificial butadiene rubber in increasing. The economic value of the rest of the BB faction however, it is small and only part of it was used as a chemical starting material and most of it as Fuel used up.

However, this remainder of the BB product does not only contain isobutylene, but also butene-1 and butene-2 and therefore, if the residual BB-J fraction is reacted with acetic acid,

009844/1998 BADOBlGiNAL

201917S

1A-37 807

other butyl ester isomers such as sec-butyl acetate along with tert-butyl acetate in the form of an ester mixture. The boiling points of the butyl ester isomers—— n-butyl acetate, sec-butyl acetate, isobutyl acetate and tert-butyl acetate - ■ - lie close together and a separation by fractional Distillation is troublesome.

Since the remainder of the BB fraction also has considerable amounts of Contains saturated hydrocarbons, result from a reduction in the yield due to the inert substances economic difficulties. '

Further intensive investigations were carried out and it was finally found that 'if the reaction between the residual BB fraction and acetic acid at a temperature of below 40 ° C in the presence of an acidic catalyst and im is carried out substantially under atmospheric pressure, the isobutylene in the remaining BB fraction is preferably carried out with acetic acid reacts and the butanes, butene-1 and butene-2 remain unchanged can be recovered from the reaction mixture. In this way, the tert-butyl ester can be produced selectively.

The product resulting from this process therefore contains essentially no other isomers and the purification operations can be easily carried out. Furthermore can the recovered fraction at elevated temperature and reacted with further organic acid under pressure to give a butyl ester mixture, "das consists essentially of sec-butyl ester. According to the process of the invention, the entire olefin content in the Residual BB fraction can be converted into butyl ester with unusually high yields in each case. If on the other hand the rest of the BB group reacted directly with the carboxylic acid compound according to the usual methods at elevated temperature

0098U / 1998

O am

1A-37 807

butene-1 and butene-2 are converted to the butyl ester, while most of isobutylene is not the carboxylic acid reacts, but polymerizes, reducing the yield based on the olefins in the remaining BB fraction is reduced. The process according to the invention can of course also be applied to other hydrocarbon mixtures which contain C ^ olefins, but the remainder BB fraction is a typical and economical starting material for this process.

The residual BB fraction used for the process according to the invention is obtained by removing butadiene from the so-called BB fraction, which is obtained exP by thermal or catalytic cracking of the gas content obtained in the fractional distillation of petroleum. ^UT $ ffi.s before processes for removing the butadiene from the BB fraction include the CAA process, in which a copper acetate-ammonia solution is used as the extractant, the furfural process, the acetonitrile process, the GPB process, and the dimethylformamide used, the UCC process, which uses dimethylacetamide, and the BASF process, which uses N-methylpyrrolidone »

The typical composition varies the residual BB-fraction ö ^e on the composition of the starting material and the time spent on the removal of the butadiene method lies in the following range:

propane 0 - 1 Propylene 0 - 5th n-butane 1 - 50 Isobutane 1 - 20th Butene-1 10 - 60 trans-butene-2 2 - 25th

- 5 -

09844/1998 BAD ORICHNAt

its 1 , 1A-37 807 ''' ^: - ■. ~ 5 ■ · ' cis-butene-2 0.1 - 25th Isobutylene -60 Butadiene - 5 ■

Other hydrocarbon mixtures than the Best-BB-Fraktian, which contain C ^ olefins and their composition in the above specified range can also be used in both liquid and gas forms.

The process according to the invention for the production of tert-butyl ester is generally carried out in such a way that the hydrocarbon mixture containing the C ^ olefins in the form of a Introduces gas into the carboxylic acid compound or its solution or by adding the carboxylic acid compound or its Adding solution to the liquid hydrocarbon mixture, where in both cases essentially under atmospheric pressure

and a temperature below 40 ⁰ C with stirring and in the presence of an acidic; Catalyst is working. The reaction temperature is kept in the range given above, taking into account the type of catalyst, the isobutylene content in the hydrocarbon mixture and the reaction time. considered. However, it is beneficial to keep the reaction temperature below 20 ° C. .

Although a lower Eeaktionstemperatur leads to a higher selectivity occurs below -20 ⁰ C, especially in the case of acetic acid, sometimes solidification of the carboxylic acid compound. Therefore, a reaction temperature of approximately ⁰ ° C. is used in commercial production. On the other hand, if the process is conducted so that the carboxylic acid is added to the hydrocarbon mixture containing the C 1-4 olefins, lower temperatures, such as about -15 ° C, can be used. In order to keep the temperature of the reaction mixture in the above range, the coolant is through a cooling jacket or

009844/1998

1A-57 807

■. ; ■■■. · ■ - ■■■■ ... -6 - -. ■ -

a cooling coil that surrounds the reaction vessel The reaction can be carried out under pressure, but higher pressure leads to a reduction in the yield and requires complicated equipment. The reaction time is generally between 1 and 5 hours and advantageously between 2 and 3 hours if one works intermittently: · "- ~ - ~ i. Although the reaction is carried out in more than 5 hours, the reaction rate is so slow not only unnecessary if there is sufficient cooling, but also results in poorer utilization of the equipment. If the process is carried out continuously, the fc response time can be further reduced and the unreacted Isobutylene cannot be used together with the others reacting components can be recovered and returned to the cycle. After the reaction has ended is, the unreacted constituents and the solvent, if any, can be removed from the reaction mixture by vacuum distillation and the tert-Butyl ester is produced in good yields after the unreacted carboxylic acid and moisture have been removed obtain. By condensing the constituents distilled off in vacuo, almost all of the butene-1 and butene-2, contained in the hydrocarbon mixture is recovered will.

If, in addition, a butyl ester mixture containing n-, sec- and isobutyl esters is to be prepared, the second reaction is carried out in such a way that the constituents recovered in the distillation are brought together with the carboxylic acid compound in an autoclave in the presence of an acidic catalyst and under pressure to a temperature in the range between 60 and 120 ⁰ C, preferably between 80 and 100 C, heated. A similar catalyst to that used for the preparation of the tert-butyl ester can also be used for this second reaction. The pressure used can vary within a wide range, but the reaction times are unusually long at low or atmospheric pressure er * - . 009844/1908 ■ -

1A-57 807

required and for commercial manufacturing processes

■ 2 pressures between 20 and 40 kg / cm are applied. A reaction temperature of more than 120 G ⁰ leads to the polymerization of butenes and a temperature below 60 ⁰ C are .from the other hand, very slow reaction rates. The reaction time for the second reaction, when working in individual batches, is between 1 and 6 hours and preferably between 2 and 3 hours. ν

Carboxylic acids which may be used for the inventive process are, inter alia, aliphatic mono- or polycarboxylic acids, such as acetic acid, propionic acid, butyric acid, i caproic acid, caprylic acid, capric acid, succinic acid, adipic acid and sebacic acid; cycloaliphatic carboxylic acids such as tetrahydrophthalic acid and aromatic carboxylic acids "such as benzoic acid, p-oxybenzoic acid, phthalic acid and trimellitic acid. The anhydrides of these acids can also be used along with an amount of water sufficient to cleave the ring.

In the process according to the invention for the preparation of the tert-butyl esters, the amount of the C. 1.05 and 1 mol of isobutylene are present per carboxyl group equivalent. Although a larger amount of isobutylene leads to higher yields of tert-butyl ester, based on the carboxylic acid used, it at the same time leads to a deterioration in the yield based on isobutylene used Excess of isobutylene is used or if the degree of conversion of isobutylene is kept low, the recovered C _x , fraction can be returned to the cycle.

009844/1998 '

ORIGIfSlAL BATHROOM

1A-37 807

If a butyl ester mixture containing sec-butyl ester is also prepared, the amount of carboxylic acid used for this second reaction should be chosen so that the ratio of 1-butene and 2-butene in the remaining CL fraction to the carboxyl groups in the The range is between 1.3 and 3.0. As in the preparation of the tert-butyl esters, better yields of the butyl ester mixture, based on the carboxylic acid, are obtained if an excess of the butenes is used. Since an excess of the butenes can be easily recovered without a part being lost through polymerization, a large excess of the butenes can be used in order to achieve high yields.

Acid catalysts which can be used for the process according to the invention include the usual catalysts as used for the reaction between acetic acid and butenes. Typical examples of this are concentrated sulfuric acid, silicic acid, phosphoric acid, polyphosphoric acid and boron trifluorido. The catalyst is used in an amount that varies depending on the type of catalyst and, for example. between 0.05 and 0.5 mol of sulfuric acid per mol of carboxylic acid "is _β An amount of more than 0.5 mol of catalyst is not favorable, as it can lead to dimerization of the butenes",

According to the process according to the invention, tert-butyl esters are produced selectively and economically in excellent yields by starting from the cheap starting material Eest-BB-Praktion. The resulting tert-butyl esters are not contaminated by other butyl ester isomers. there is no polymerization of isobutylene. »In addition, a mixture of n-, sec» and isobutyl esters can be prepared with good yields «. In this way, the useless residual BB fraction with a high

009844 / .1998
ßAD ORIGINAL

1A-37 80? ·.

Effectively converted into useful chemical products will. The invention is illustrated in more detail by the following examples.

Example 1

1st reaction - production of tert-butyl ester .

120 parts of acetic acid and 20 parts of concentrated sulfuric acid (98 %) were placed in a reaction vessel equipped with a gas inlet, a stirrer, a cooling jacket and a gas outlet connected to a condenser and a cooled trap. The temperature was maintained at 5 ° C by passing coolant through the jacket. 216 parts of residual BB fraction, of the composition given in Table I, were gradually passed over the course of 1.5 hours through the gas inlet into the liquid phase of the reaction vessel and the reaction mixture was then stirred for 10 minutes. The unreacted gas emerging from the reaction vessel was passed through the gas outlet into a condenser, where the unreacted CL mixture was collected as condensate. After the reaction had ended, a vacuum of 200 mmHg was applied to the reaction vessel in order to completely remove the unreacted CL portion from the reaction mixture. The volatile substances were collected in a refrigerated trap. 200 parts of water were then added to the residue in the reaction vessel with stirring and, after settling, the upper ester layer was removed from the lower water

* ■ "... ■" ■■

layer separated. Moisture contained in the ester layer was removed by anhydrous Glauber's salt and the dried ester layer was distilled. 197 * 4 parts of pure tert-butyl acetate were obtained. The yield, calculated on the acetic acid used, was 84.9 %. There were 113.8 parts of unconverted C 1-4 fraction (II), the composition of which is also given in Table I, in the

- 10 009844/1998

1A-37 807-10 condenser and the cooled trap recovered.

2nd reaction - production of a butyl ester mixture

55.7 parts of acetic acid, 18.6 parts of concentrated sulfuric acid and 114 parts of the recovered C ₁ , mixture (II) were placed in a corrosion-free autoclave equipped with a stirrer, a thermometer and a heater. The reaction was · within 4 h under stirring at a temperature of 90 ⁰ G and a pressure yon 30 kg / cm performed. After the reaction had ended, the again unreacted portion of the C ^ fraction was drawn off and collected in a cooled trap by means of a condenser. 100 parts of cold water were then added to the reaction mixture in the autoclave with stirring and, after it had settled, the upper ester layer was separated off, dried with anhydrous Glauber's salt and distilled. 92.3 parts of a butyl acetate mixture were obtained. The yield, based on the acetic acid used, was 85.4%. 50.5 parts of unreacted C 1-4 fraction (III), the composition of which is also given in Table I, were recovered in the condenser and the trap.

TABLE LE I back
happier
proportion of
(III) Rest-BB-
fraction
α) back
happier
proportion of
(II) 7.3 %
48.8
12.7
28.8
2 _S 4 Isobutylene
Butene-1
Butene-2
Butane
miscellaneous 54.5 %
24.8
12.5
7.2
1.0 16.4%
45.7
23.0
13.2
1.7

- 11 -

009844/1098

1A-37 807

- 11 - "■

Be is ρ ie 1 2 . '. "■"

1 «reaction - production of tert-butyl ester .

120 parts of acetic acid and 30 parts of concentrated sulfuric acid were placed in a similar reaction vessel to that shown in Example 1 has been described. 216 parts of the remainder of the BB promotion "Cl) were gradually introduced into the reaction vessel. Example 1 was used. One received 208 parts of tert-butyl acetate. The yield based on the acetic acid used was 89.5% · 108.3 parts of CL fraction (IV) having the composition shown in Table II were recovered.

2nd reaction - production of a butyl ester mixture

55 »7 parts of acetic acid, 18.6 parts of concentrated sulfuric acid and 108 parts of the recovered C ^ fraction (IV) were placed in an autoclave similar to that described in Example 1. The reaction was also carried out as in Example 1. 92.3 parts of butyl acetate mixture were obtained. The yield, based on acetic acid, was 86.1 %. 44.2 parts of C 1-4 fraction (V) with the composition shown in Table II were recovered.

Isobutylene

Butene-1

Butene-2

Butane

miscellaneous

TABLE II recovered recovered proportion of proportion of (V) (IV) 5.9 % 12.0% 44.8 47.9 14.2 24.2 32.9 13.9 - 2 _S 2 - 2.0

- 4P -

00-9-8AA / 19-98 BATH ORIGINAL

. 1A-37 807

Example 1 3.

1st reaction - production of tert-butyl ester

120 parts of acetic acid and 10 parts of boron trifluoride ethyl ether were placed in a similar reaction vessel as in Example 1. 216 parts of solid BB fraction (i) were gradually introduced into the reaction vessel. "The procedure was as in Example 1," 182 parts of tert-butyl acetate were obtained. The yield. based on the acetic acid used, was 78.3 %. 120.4 parts of C ^ fraction (VI) with the composition given in Table III were recovered.

2o Healction ° Production of a butyl es tergemis ehe s

55.7 parts of acetic acid, 4 parts Bortrifluoridäthylätherat and 120 parts of the recovered C ^ -Praktion (VI) were 'added to a similar autoclave as in Example 1. The procedure was as in Example 1' was obtained 82 "7 parts Birtjlacetatgemisciia Di yield © _s based on acetic acid, was 7635 % o 53.2 parts of 0 ^ fraction (VII) with the composition given in Table III were recovered.

T A B E L L E III

more relaxed, more recovered

Share share

(VI) '(VII)

21.7 % 5.8 %

1 . 43 _S 1. 51 ₉ 5

2 21.8 - 13 ₉ 5 " butanes. 12 _S 5 27 ₉ 1

1 ₉ 9 2.1

009844/19

. 1A-37 807

- 13
Example 4

120 parts of acetic acid and 40 parts of concentrated sulfuric acid were placed in a similar reaction vessel as in Example 1. 485Teile residual BB fraction (VIII) having the composition in Table IV were initiated h into the reaction vessel at a temperature of 20 ⁰ G within the second The procedure was as in Example 1, the gas withdrawn from the reaction vessel being introduced directly into the autoclave, which contained 60 parts of acetic acid and 20 parts of sulfuric acid. The second reaction was carried out within 3 h at a temperature of 11O ⁰ C and a pressure of

2
35 kg / cm. After the reaction had ended, the unreacted portion of the C ^ fraction was drawn off and collected in a condenser and a cooled trap. The products formed in the reaction vessel and the autoclave were combined and treated further as in Example 1. 293 parts of butyl acetate mixture were obtained and the overall yield, based on the acetic acid used, was 83.8%. 290 parts of the C 1-4 fraction were recovered.

TABLE IV

Remainder BB group Remaining BB promotion (VIII) (IX) Isobutylene 24.8 % 44.7 % Butene-1 13.0 .15.2 Butene-2 21.7 18.6 Butane 38.7 20.1 Butadiene 1.2 0.5 miscellaneous 0.6 0.9

.14 -

00984.4 / f 9.98

1A-37 80?

Be i s ρ i e 1 5

250 parts of residual BB fraction (IX) with a in.Tabelle IV given composition were placed in a similar Resktionsgefäß as in Example 1 and cooled to -20 ⁰ C. A mixture of 90 parts of acetic acid and 37.5 parts of sulfuric acid was gradually added over the course of 1 hour with stirring and the unreacted portion of the G ^ fraction flowing out of the gas outlet was continuously passed under pressure into an autoclave, which was 30 Parts of acetic acid and 15 parts of sulfuric acid. The reaction was carried out at L 100 ^° C. and a pressure of 30 kg / cm. After the end of the introduction of the O ₂ fraction into the autoclave, the reaction was carried out for a further 2 1/2 hours while stirring at the same temperature. The unreacted portion of the O 2 fraction was drawn off The reaction products formed in the autoclave were combined and treated further as in Example 1. 206 parts of butyl acetate mixture were obtained. The total yield ». based on the acetic acid used, was 88.5%. 120 parts of C ₂ fraction were recovered »

B e i a ρ i e l____jS -

"120 parts of acetic acid and 30 parts of phosphoric acid were placed in a similar reaction vessel as in Example 1. 216 parts of residual BB fraction (I) were gradually introduced into the reaction vessel -Butyl acetate *. Di® Yield ₈ based on the acetic acid _{9 used} was S2 ₉ 2 % _a 126 “5 parts G ^ fraction were

1A-57 807 - 15 example £

1st stage - production of tert-butyl ester

30 parts of phthalic acid, 7.2 parts of concentrated sulfuric acid and 30 parts of tetrahydrofuran were placed in an autoclave similar to that described in Example 1. 41 parts of liquefied residual BB fraction (I) were added. The reaction was under stirring at a temperature of 30 ⁰ C

ο
and a pressure of 20 kg / cm within 2 hours. The gas emerging during the reaction was passed through the gas outlet into a cooler and the unreacted portion of the C ^ fraction was collected as condensate. After the reaction had ended and the unreacted C _{/ 4} fraction had been removed in vacuo, the reaction mixture was neutralized with aqueous sodium carbonate. 18 _S 1 parts of di-tert-butyl phthalate could be extracted with ethyl ester. 16.5 parts of unconverted phthalic acid were recovered from the residue. The yield, based on the converted phthalic acid, was 80.3 % .30.4 parts of C ^ fraction (X) with that given in Table V. Composition were recovered.

2nd stage - preparation of a butyl ester mixture

18.5 parts of phthalic acid, 4.4 parts of concentrated sulfuric acid, 28 parts of tetrahydrofuran and 30 parts of the recovered 'C ^ fraction (X) were placed in a similar autoclave as given in example 1.

The second reaction was carried out with stirring at a temperature of 100 ^° C. and a pressure of 40 kg / cm over the course of 5 h. The reaction mixture was treated further as in the first reaction. 15 parts of dibutyl phthalate mixture are obtained. 5 »7 parts of unreacted phthalic acid

0098 ^ 4/1998

1A-37 807 - 16 -

were recovered. The yield, based on the converted phthalic acid, was 67.6%. 11.3 parts of unreacted C ₂ fraction were recovered.

V Isobutylene TABLE V recovered - Butene-1 recovered proportion of Butene-2 proportion of (XI) Butane (X) miscellaneous 29.7% 44.4 % 38.4 30.3 19.3 15.2 11.1 8.9 1.5 '1.2

Example B.

1. "Reaction - H preparation of tert-butyl ester

43.3 parts of n-caprylic acid ^ 6.0 parts of concentrated sulfuric acid and 86.5 parts of toluene were placed in a similar reaction vessel as in Example 1. 40 parts of Eest-BB-Prakt (I) were gradually introduced into the reaction vessel. Example 1 was used. It was neutralized with aqueous sodium carbonate, dried with anhydrous Glauber's salt and distilled * 44.4 parts of tert-butyl caprylate were obtained. M © Yield, based on the caprylic acid was 73 ^ 9 % m 24.1 parts of unreacted C ^ fraction (XI) with the composition given in Table V were recovered «

• 9844 / 1B9

11-37 807

- 17 -

2nd reaction - production of a butyl ester mixture

17.9 parts of caprylic acid, 2.5 parts of concentrated sulfuric acid, 36 parts of toluene, and 24.1 parts of the recovered G ₂ traction (XI) were placed in an autoclave similar to that in Example 1. Me second reaction was within 5i5 h "at a temperature of 100 ⁰ C and a pressure of 40 kg / cm performed. ' React Bas-ionsgeiiiisch was further treated similarly as in the first reaction. This gave 19.0 parts Butylcaprylatgemisch. The yield based on caprylic acid, was 76 "x 9 5%> 6 parts C ^ fraction were recovered...

Yer ^ example

120 parts of acetic acid and 30 parts of concentrated sulfuric acid were placed in a similar reaction vessel as in Example 1. 216 parts of residual BB fraction (I) were gradually in initiated the reaction vessel. The procedure was as in Example 1, with the exception that the temperature was increased to 600.degree was held.

After the reaction had ended, the reaction mixture was worked up as in Example 2. 137 parts of a were obtained oily substance. Gas chromatographic examination showed that this oily substance contained 20 parts of tert-butyl acetate (Yield, based on the acetic acid used, 8.6%), 27 parts of sec-butyl ester and considerable amounts of dimeric or polymeric isobutylene. 86 parts unreacted C ^ - Fraction (XII) with the composition given in Table VI was recovered.

4-8 parts of acetic acid, 16 parts of concentrated sulfuric acid and 86 parts of the recovered CL fraction (XII) were in

- 18 -

009844/1998
BADOWÖtNAL

807

an ätelieiiea autoclave me given in Example 1. The second reaction was carried out according to BaExample 2. ¹ You received dta? © !! Destillatioa 79 parts of butyl acetate mixture "The yield, Ibeso on acetic acid," was 85 ,? ' % * 40 parts of G ^ fraction (XIII), with the composition given in Table YI, were returned

! ABELLi ¥ 1

recovered recovered proportion of proportion of (HI) (XIII) Isobutylene - 5.8 % 5.0% Butene-1 51 * 2 42.5 Butene-2 ■ 23.3 15.0 Butane "■ '17.4- 35.0 miscellaneous ■ 2.3 2.5

PATEKTANSPEACH:

009844/1998

Claims (4)

DR.ING. F. WTIBSTHOFF 8 MUNICH SO DIPImINCCPIJT-S SCBWSIOXRSTBASSS S DR-KT-PECHSu fiX tkun »SSSBSl DR. ING. D. BBHKKNS iiuauixunmii PATENT LAWYERS trmaxMtttrjatwMT Jf B »ob« k 1A-37 - 19 - PATINTABLES Process for the preparation of tert-butyl esters, and optionally a mixture of butyl esters containing them, from an aliphatic hydrocarbon mixture containing isobutylene and n-butenes, with a carboxylic acid compound in the presence of an acidic catalyst, characterized in that the temperature is below 40 ° C and optionally converts the unreacted hydrocarbons in a 2nd process stage at a temperature between 60 and 120 ⁰ G and the tert-butyl ester or the ester mixture from the reaction mass in a known manner. 2) Method according to claim 1 »thereby geke η η show η et that the residual BB fraction is used as the aliphatic hydrocarbon mixture, which remains after removal of I butadiene from a C ^ -Fraction 5 on and n-butane 1-50 $ Isobutane 1 - $ 20 Butene-1 10-60 ^ trans-butene-2 2 - 25% tis-butene-2 1 - 25S ^ Isobutylene 5 - 60 # butadiene 0.1; - 3% Cx and Cc ^ ai parts 0 - 556 ea "uaalt. 3) Method according to claim 1 or 2, characterized in that - Mark rejects that stan act as an acidic catalyst 0G9844 / 1998 1A-37 807 Sulfuric acid, phosphoric acid, polyphosphoric acid, silica and / or boron trifluoride is used. 4) Method according to claim 1 to 3 $ characterized in that as. Carboxylic acid compound acetic acid or phthalic acid or their anhydrides used * · · · 009844/1998