DE1643654C - Process for making bicyclo square bracket to 2,2,2 square bracket to oct 7 en 2,3,5,6 tetracarboxylic dianhy dnd - Google Patents

Description

ethers liquid at room temperature, carboxylic acid

amides and / or nitriles. Suitable additives for the catholytes are, for. B. dioxane, tetrahydrofuran, CiIykolmonomethyläther. Dimethylformamide or acetonitrile. According to application P 15 68 094.1-42, the procedure is analogous, optionally without a solvent but lead, cadmium, amalgamated as cathodes. Tin, thallium or bismuth or alloys at least two of the metals lead, mercury, silver, cadmium, tin, thallium and bismuth, in addition can be amalgamated, or pure cadmium. tin

From the German Auslegeschrift 1 234 211 it is known that one 3,6-endoäthyleno-l, 2,4,5-cyclohexanetetracarboxylic acid dianhydride (= Bicyclo- [2,2,2] -oct-7-en-2,3,5,6-tetracarboxylic acid dianhydride, BTA) by converting 3,5-cyclohexadiene-1,2-trans-dicarboxylic acid with maleic anhydride in the presence of acetic anhydride at temperatures from 50 to C receives. This method gives good results when the cyclohexadiene dicarboxylic acid

in this process increased to 100 ° C. The reaction mixtures obtained are worked up in the older processes preferably at low temperatures, especially below 30 C, so that

is extremely pure. If you have, for example, 30 or bismuth; this is the reaction temperature Cyclohexadiene-trans-dicarboxylic acid used by electrochemical reduction of o-phthalic acid has been manufactured, it requires careful,

expensive cleaning, e.g. B. by recrystallization ^ .i ^ .. * ..., ... "^ ... w— ■ -

from boiling water in the presence of activated carbon. 35 bearings of the educated 3.5

The troublesome impurities are dicarboxylic acids and should be avoided. It is now possible those that cannot be detected analytically, but by distilling off the ether or by which only becomes noticeable in the reaction with maleic anhydride through a reduction in yield do.

It has now been found that bicyclo- [2,2,2] -oct-7-ene-2,3,5,6-tetracarboxylic acid dianhydride can be obtained by reacting 3,5-cyclohexadiene-1,2-trans-dicarboxylic acid with maleic anhydride in the presence of “.... ^. "" -, .- ", anhydrides of low molecular weight alkanecarboxylic acids 45 acid anhydride. at temperatures of 50 to 150 ^° C., it is particularly advantageous if 3,5-cyclohexadiene-1,2-trans-dicarboxylic acid is first obtained in the anhydride of the low molecular weight alkanecarboxylic acid in the presence of active ones

em by distilling off the ether or Dilute the ether-, carboxamide- or nitrile-containing catholyte with mineral acids immediately to use the crude product obtained from the catholyte mixture without further additional purification.

Suitable anhydrides of low molecular weight alkanecarboxylic acids are, for. B. those of alkanecarboxylic acids with 2 to 4 carbon atoms, especially acetic acid

Of the adsorbents mentioned, some show a particularly favorable influence on the Implementation, e.g. B. the active carbons designated as R, TW, H, M or RU carbon. A characteristic

cooked by active, "», ".,. uw ^ n. ··· ».». !! omi> ui »mnui. umc>. iuuaiucri-

Coals with an inner surface of > 500 m ² / g, 5 ° sization of the coals is given in the following table of bleaching earth, silica gel, aluminum oxides or aluminum:

Activated carbon Inner surface Miners Ciesamtpor- designation Manufacturing m ² g Pore radius
Λ volume
cm'g R. Lignite activated with steam -600 -46 -1.4 TW Peat charcoal activated with steam -650 -74 -2.4 H Charcoal activated with steam -915 -57 -2.6 RU Acetylene black activated with steam -900 -25 -1.0 M. Lean coal activated with steam -735 -15 -0.5 Carboraffin Sawdust activated with zinc chloride -1320 -35 -2.4

When using R-, TW- and Η-carbon it is sufficient
an addition of 0.1 to 1 percent by weight,
based on 3,5-cyclohexadiene-1,2-dicarboxylic acid. at

for other active coals and other adsorbents, however, it is expedient to add 1 to 5 percent by weight the adsorbent, based on 3,5-cyclo-

hexadiene-1,2-dicarboxylic acid, apply. Remarkable is that the yield of BTA is reduced if the adsorbent is removed before the addition of the Maleic anhydride for dissolving 3,5-cyclohexadiene-1,2-dicarboxylic acid filtered off.

The process can be carried out either batchwise or continuously.

The 3,5-cyclohexadiene-l, 2-dicarboxylic acid is heated with the anhydride of low molecular weight alkanoic acid in the presence of the adsorbent to the reaction temperature, that is 50 to 150 ⁰ C, but preferably to reflux. One uses S ^ -Cyclohexadiene-l ^ -trans-dicarboxylic acid and that

usually in a molar ratio of 1: 1 to 1:10, in particular before. 1: 2 to 1: 7. and adds the adsorbent in the above-mentioned amount. After brief heating, e.g. B. about 5 to 10 minutes, filtered if necessary, the adsorbent and then gives the maleic anhydride, expediently in a molar ratio of 3,5-cyclohexadiene-1,2-dicarboxylic acid to maleic anhydride such as 1: 0.9 to 1: 1.5. especially 1: 1.0 to 1: 1.3, and holds that Reaction mixture for a further 10 to 20 minutes at the reaction temperature. After cooling, separate the precipitated solid components and washing with low molecular weight alcohols such as methanol, Acetone or water, the BTA formed is dried. In many cases, adsorbents are a problem further processing, e.g. B. in the reaction with alcohols for the production of plasticizers, not, so it is not necessary to separate it beforehand.

In the continuous procedure, 3,5-cyclohexadiene-1,2-dicarboxylic acid is heated with the corresponding amount of the anhydride of the low molecular weight alkanecarboxylic acid with the addition of the adsorbent and the suspension is pumped over a heating section into a stirred tank cascade consisting of two to three stirred vessels. The heating zone is kept at the reaction temperature. If acetic anhydride is used and temperatures between 130 and 138 C are maintained, residence times of 5 to 10 minutes are sufficient. Appropriate dwell times must be observed at other temperatures. If the adsorbent is removed before the addition of maleic anhydride, it is expediently filtered off before being fed into the stirred tank cascade. The amount of maleic anhydride corresponding to the cyclohexadiene dicarboxylic acid is fed in liquid form to the first stirred tank of the cascade. Depending on the size of the container, the throughput and stirring speed in the stirred tank cascade, residence times of 10 to 60 minutes have proven useful. Thorough mixing by vigorous stirring, if necessary by means of internals in the stirred tank, is advisable so that BTA which has formed and which has crystallized out is discharged evenly. The reaction temperature in the first stirred tank cascade is expediently kept at 130 to 140 ^° C., while in the last stirred tank it is expedient to cool to room temperature and thus achieve an almost quantitative precipitation of the BTA. BTA is processed as in discontinuous production.

example 1

l.-s a 1-1 four-necked flask fitted with a stirrer, thermometer. The reflux condenser and tube for adding solids are provided, 173.2 g of crude cyclohexa-3,5-diene-1,2-dicarboxylic acid (97% = 1 mol 100%), produced by electrochemical hydrogenation of o-phthalic acid in tetrahydrofuran-containing dilute sulfuric acid 0.85 g of R-carbon (0.5%, based on the crude acid) and 530 g of acetic anhydride (5 mol) heated to 135 ° C. under reflux with stirring. It heats up quickly, around 15 minutes. After a reaction time of 10 minutes, the reaction mixture is rapidly ^{cooled to ~ 100 to 120 °} C., and 107.5 g (1.1 mol) of maleic anhydride are added to the reaction solution. The reaction mixture is then boiled for 15 minutes under reflux

If the reaction is the reaction mixture with ice water cooled to -15 ° C and the precipitate filtered off. After washing with methanol, it becomes dried. By concentrating the filtrate to half the volume, only traces of BTA received. The yield of bicyclooctene dianhydride is 246 g (= 99.2% of theory); M.p .: 354.5 up to 355.5 ° C.

Example 2

The procedure is as in Example 1, but the reaction time is limited before the addition of maleic anhydride on 1 minute. The yield of BTA is 219 g (= 88.3% of theory).

Example 3

The procedure is as in Example 1, but the reaction time before the addition of maleic anhydride is extended on 60 minutes. The yield of BTA is 215 g (= 86.8% of theory).

Example 4

The procedure is as in Example 1, but before the addition of maleic anhydride, the R-charcoal is filtered off with the aid of a suction filter. After the addition of maleic anhydride to the filtrate, the reaction mixture is refluxed for 15 minutes. The yield of BTA is 239 g (= 96.4% of theory); M.p .: 355 to 356 ° C.
45

Example 5

If the reaction according to Example 1 is carried out for comparison in the absence of activated charcoal, so the yield of BTA is only 184.8 g (= 72.5% of theory); M.p .: 354 to 355 ° C.

If the R-carbon is only added to the reaction solution with the maleic anhydride, the yield of BTA is 206.5 g (= 83.3% of theory). 55

Example 6

In a 6-1 glass flask with a bottom valve, a Solution of 24.6 percent by weight cyclohexa-S.S-diene-1,2-trans-dicarboxylic acid (Raw material, 97%), 75.25 percent by weight acetic anhydride and 0.15 percent by weight TW carbon (= 0.75%, based on the dicarboxylic acid) presented and gently stirred to a Avoid settling of the charcoal (molar ratio of raw dicarboxylic acid to acetic anhydride = 1: 5). Via a 1-1 dropping funnel, 0.66 liters (~ 0.74 kg) of this mixture are added every hour with a metering pump through a heating section into a cascade consisting of

two notched 250 cm ³ -Rührkolben pumped. A double-jacket tube with a snake neck made of glass is used as the heating section. The temperature is 130 to 135 ° C. The heating takes place with glycerine from a thermostat, the volume of the heating zone is 110 cm ³ , and the residence time of the reaction mixture is 10 minutes.

Liquid maleic anhydride is fed into the first stirred flask with a heated metering pump in an amount of 113 g / hour. The reaction temperature in the cascade is 133 to 138 C. The flasks are equipped with reflux condensers. The volume of the reaction mixture in each of the two flasks is kept at about 100 to 110 cm ³ , so that the residence time in the cascade is about 20 minutes.

η KoIl

The second flask is followed by a cooling vessel in which the BTA-containing reaction mixture is added is cooled to 15 ° C with stirring. The precipitate is collected on a suction filter and with Methanol washed. Then the line BTA is dried; the melting point is 354.5 bis 356 C. With a throughput of 5.18 kg of dicarboxylic acid / acetic anhydride mixture (i.e. 1.275 kg raw dicarboxylic acid = 1.237 kg 100%) 1.8 kg BTA are obtained. The yield is 98.6% the theory.

The following table shows the results of examples which were carried out under test conditions as Example 6 are carried out, the TW carbon being replaced by other adsorbents

Adsorbent

Yield of BTA
in theory

H-Kohlc
0.75%

93.4

example

K)

0.75%
80.2

0.7

0.75%
85.1

81.3

1:

Carboraffin RU-coal M-coal I fuller's earth! ; -AI ₂ C),

85.7

Claims (1)

Claim: Process for the preparation of bicyclo [2 ^>, 2] -oct - 7 - ene - 2,3,5,6 - tetracarboxylic acid - dianhydride by reacting 3,5-cyclohexadiene-l ^ -transdicarboxylic acid with maleic anhydride in the presence of anhydrides Low molecular weight alkanecarboxylic acids at temperatures of 50 to 150 ⁰ C, characterized in that SS-cyclohexadiene-l ^ -trans-dicarboxylic acid in the anhydride of the low molecular weight alkanecarboxylic acid in the presence of active carbons with an internal surface of> 500 m ² / g. Whitening earth, silica gel, aluminum oxides or aluminum hydroxides or mixtures of such adsorbents are heated to the reaction temperature and only then is the maleic anhydride added. 3,5-Cyclohexadiene-1,2-trans-dicarboxylic acid can to use in pure form; however, it is an advantage of the process that it can be used as used in the electrochemical reduction of o-phthalic acid, e.g. B. after registration P 16 18 078.2-42 or according to application P 15 68 094.1-42 or according to the method of USA patents 2,477,579 and 2,477,580. According to application P1618 078.-2-42, 3,5-cyclohexadiene-1,2-trans-dicarboxylic acid is obtained by electrochemical hydrogenation of o-phthalic acid in dilute aqueous sulfuric acid nium hydroxides or mixtures of such Adsorp- 15 at temperatures up to 8O ⁰ C, especially below 70 ⁰ C, ttv.ιι., ιιΐιι ^ ι heated to uic ixcaMionsiemperaiur at Mromaicnten of 1 dis / um "unier use and only then the maleic anhydride is added Conventional cathodes with the addition of water miscible, inert under the reaction conditions.