Classifications

• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C63/00—Compounds having carboxyl groups bound to a carbon atoms of six-membered aromatic rings
  • C07C63/14—Monocyclic dicarboxylic acids
  • C07C63/15—Monocyclic dicarboxylic acids all carboxyl groups bound to carbon atoms of the six-membered aromatic ring
  • C07C63/16—1,2 - Benzenedicarboxylic acid
  • C07C63/22—Halides thereof
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C51/00—Preparation of carboxylic acids or their salts, halides or anhydrides
  • C07C51/58—Preparation of carboxylic acid halides
  • C07C51/60—Preparation of carboxylic acid halides by conversion of carboxylic acids or their anhydrides or esters, lactones, salts into halides with the same carboxylic acid part
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C51/00—Preparation of carboxylic acids or their salts, halides or anhydrides
  • C07C51/58—Preparation of carboxylic acid halides

Definitions

• the present invention relates to a process for the preparation of Phthalcicredi ⁇ chloride by reacting phthalic anhydride with a chlorinating agent (I) selected from the group of thionyl chloride and phosgene, in the presence of a cata- gate at a temperature of 80 to 200 0 C and a pressure of 0.01 to 10 MPa abs.
• a chlorinating agent (I) selected from the group of thionyl chloride and phosgene
• Phthalic acid dichloride is an important starting material in the production of plasticizers and synthetic resins. Furthermore, phthalic acid dichloride is also used as synthesis component in the production of active ingredients, such as, for example, pharmaceuticals and crop protection agents.
• Phthalic acid dichloride is generally prepared by reacting phthalic anhydride with suitable chlorinating agents.
• No. 2,051,096 describes the preparation of phthaloyl chloride by reacting phthalic anhydride with trichloromethane or tetrachloromethane in the presence of zinc chloride.
• This method has a number of disadvantages. For example, the use of chlorinated hydrocarbons from today's environmental perspective is rather problematic. In addition, said process requires a high reaction temperature of about 220 to 300 ° C.
• DE-A 20 36 171 teaches the preparation of phthaloyl chloride by reacting phthalic anhydride with trichloromethyl isocyanate dichloride in the presence of a Lewis acid, in particular zinc chloride, iron (III) chloride or aluminum chloride.
• a Lewis acid in particular zinc chloride, iron (III) chloride or aluminum chloride.
• a disadvantage of this method is the formation of stoichiometric amounts of Chlorcarbonylisocy- aniddichlorid and fumaric acid as coupling products, which are separated from the desired product phthaloyl chloride and dispose of consuming.
• the work-up of the resulting reaction mixture is complicated due to the use of metal cationic Lewis acids (see above).
• a common disadvantage of the abovementioned processes is the mentioned formation of stoichiometric amounts of coproduct which remains in the reaction mixture and which is separated from the valuable product phthaloyl chloride and is expensive to dispose of.
• thionyl chloride or phosgene is used as the chlorinating agent, this disadvantage does not occur, since only gaseous by-products are formed from the chlorinating agent, namely hydrogen chloride gas, sulfur dioxide or carbon dioxide, which are easily separated off.
• LP Kyrides J. Am. Chem. Soc. 59, 1937, page 206 to 208 also the preparation of phthaloyl chloride by reaction of phthalic anhydride with thio ⁇ nylchlorid in the presence of zinc chloride.
• the said process has at least the advantage over the above-mentioned processes that the chlorinating agent thionyl chloride to be used forms only gaseous by-products which are easy to separate off. Nevertheless, this method has significant disadvantages.
• N, N-dialkyl-formamides as catalyst results in the formation of amide hydrochloride adducts, so-called Vilsmeier adducts, by reaction with phosgene, which are ionic in nature and can therefore lead to problems due to solid precipitation in the subsequent distillation.
• the formed amide hydrochloride adducts can thermally decompose during the subsequent distillation and lead to contamination of the Wertpro ⁇ dukt phthalic acid dichloride.
• DE-A 40 06 370 discloses the general teaching for the synthesis of aliphatic, aromatic or araliphatic carboxylic acid chlorides from phosgene and the corresponding carboxylic acids or carboxylic anhydrides in the presence of dialkylated carboxamides and / or trisubstituted phosphine oxides and / or sulfides as phosgenation catalysts and in particular of dimethylformamide, dimethylacetamide and trioctylphosphine oxide.
• the object of the present invention was to find a process for the preparation of phthalic acid of high purity, which does not have the disadvantages mentioned above, only readily accessible and technically readily available starting materials and, if appropriate, only readily available and technically readily available auxiliaries / catalysts requires, and the educts to increase the space-time yield and to enable a technically less complex isolation of the desired product phthalic acid do not form predominantly remaining in the reaction mixture by-products.
• Fer ⁇ ner should be easily separable in the process to be found, the desired product phthaloyl chloride of any required excipients / catalysts and any resulting intermediates and by-products, any necessary auxiliaries / catalysts and their possible reaction products under the vorlie ⁇ ing conditions are not prone to solid precipitation as well as the disposal of any necessary auxiliaries / catalysts be possible without much effort. Furthermore, even under mild temperatures and pressures, the process to be found should lead to a high conversion of phthalic anhydride, a high selectivity to and a high yield of phthaloyl chloride, and in particular to have a high space-time yield.
• a process for preparing phthaloyl chloride by reacting phthalic anhydride with a chlorinating agent (I) selected from the group of thionyl chloride and phosgene, in the presence of a catalyst at a temperature of 80 to 200 0 C and a pressure of 0, 01 to 10 MPa abs, which is characterized in that is used as the catalyst (II) triphenylphosphine, triphenylphosphino or its mixture.
• a chlorinating agent (I) selected from the group of thionyl chloride and phosgene
• triphenylphosphine, triphenylphosphine oxide or mixture thereof used as catalyst (II) in the process according to the invention is characterized by the common structural formula (IIa)
• n 0 or 1.
• the amount of catalyst (II) to be used in the process according to the invention is generally from 0.05 to 25 mol%, preferably from 0.1 to 20 mol%, particularly preferably from 0.2 to 10 mol%, and very particularly preferably 0.5 to 5 mol%, based on the phthalic anhydride used.
• the chlorinating agent (I) used in the process according to the invention thionyl chloride or phosgene.
• the molar ratio of chlorinating agent (I) used is generally from 0.95 to 10, preferably from 0.95 to 5, particularly preferably from 0.98 to 3 and very particularly preferably from 1 to 2, based on the molar amount of phthalic anhydride used.
• phthalic anhydride the chlorinating agent (I), the catalyst (II) and any solvent to be used can be carried out in different ways and in a different order.
• the phthalic anhydride can be used, for example, melted or dissolved in an inert solvent. It is also possible to use part or all of the catalyst (II) in the phthalic anhydride, if appropriate in a countercurrent state. an additional inert solvent to solve and admit in this way.
• the addition of the chlorinating agent (I) is usually liquid when using thionyl chloride and usually gaseous when phosgene is used. Depending on that, it is also possible to add phosgene in liquid form. Furthermore, it is also possible in principle to dissolve a part or all of the catalyst (II) in the chlorinating agent, if appropriate in the presence of an additional inert solvent, and to add it in this manner. When thionyl chloride is used, it is preferable to dissolve part of the catalyst (II) therein and to supply it in this form to the phthalic anhydride.
• the catalyst (II) it may also be added separately, dissolved in the required amount of inert solvent.
• the process according to the invention is generally operated semicontinuously or continuously.
• phthalic anhydride is usually initially charged in a suitable reactor in a molten state or dissolved in an inert solvent, and the total amount of catalyst (II) or at least a part thereof is dissolved therein.
• the chlorination agent (I) which optionally contains the remaining amount of the catalyst (II) and optionally an inert solvent, is continuously added in accordance with the reaction progress.
• Suitable reaction apparatuses may in principle be all reaction apparatuses which are suitable for gas / liquid or liquid / liquid reactions, for example stirred tanks.
• Inert solvents are to be understood as meaning diluents which do not chemically react with the substances mentioned under the chosen conditions. Bevor ⁇ Trains t is one aromatic or aliphatic hydrocarbons, and phthalic acid dichloride (mp. 12 0 C). The latter has the advantage that hereby no further foreign substances are introduced into the process. If inert solvents are used, preference is given to those which have a higher boiling point than the chlorinating agent (I) used in order to avoid the boiling cooling and, moreover, for the sufficient separability of the phthaloyl chloride in the distillative workup. tion at a preferably at least 10 0 C lower boiling point, measured under normal pressure, as having phthalic anhydride.
• inert solvents are used Lö ⁇ which to ensure sufficient releasability of the Phthal Acidich- lorids preferably an at least 10 0 C higher boiling point, measured at atmospheric pressure, have as a phthaloyl chloride.
• Preferred hydrocarbons are monosubstituted or polysubstituted aromatic hydrocarbons, for example toluene, o-, m-, p-xylene, ethylbenzene, chlorobenzene or o-, m-, p-dichlorobenzene. Of these, very particular preference is given to o-, m- or p-xylene, chlorobenzene, o-, m-, p-dichlorobenzene or mixtures thereof.
• inert solvents are used in the reaction, their amount is generally up to 2000% by weight and preferably up to 1 to 1000% by weight, based on the total amount of the phthalic anhydride present and the phthaloyl dichloride formed.
• the reaction is preferably carried out with a mixture which, during the entire implementation of the reaction, contains> 80% by weight, preferably> 90% by weight and particularly preferably> 99% by weight, of phthalic anhydride, chlorinating agent ( I), catalyst (II) and intermediate, secondary and end products formed from these substances.
• the reaction is carried out in the absence of an additional solvent.
• the process according to the invention is carried out at a pressure of from 0.01 to 10 MPa abs, preferably from 0.05 to 5 MPa abs, more preferably from 0.09 to 0.5 MPa abs and very particularly preferably from 0.09 to 0, 2 MPa abs through.
• the process according to the invention leads at a temperature of 80 to 200 0 C, preferably from 100 to 180 0 C, particularly preferably from 120 to 160 0 C and most preferably from 130 to 16O 0 C.
• reaction solution obtained is generally left to react for a certain time, generally from 30 minutes to 6 hours under the reaction conditions.
• inert gas is then usually passed through under intensive mixing ("stripping").
• the reaction is generally worked up by the known methods.
• the desired phthaloyl chloride is isolated by fractional distillation.
• the catalyst (II) used triphenylphosphine or
• triphenylphosphine oxide can be recovered by distillation and used again.
• phthalic anhydride optionally dissolved in the distilled phthaloyl chloride by addition of a nonpolar solvent such as, for example, cyclohexane, petroleum ether or toluene and to separate off as a solid.
• a nonpolar solvent such as, for example, cyclohexane, petroleum ether or toluene
• the added solvent can then be distilled off again from the phthaloyl chloride.
• the desired amount of phthalic anhydride is added to a stirred tank with reflux condenser and heated about 130 to 160 0 C, so that a phthalic anhydride melt is present.
• About half of the desired catalyst (II) is added thereto with stirring.
• the addition of a liquid mixture of the thionyl chloride and the remaining catalyst (II) is started, the rate of addition being generally adjusted in such a way that the unconverted thionyl chloride boils slightly under reflux.
• reaction mixture After completion of the addition of the thionyl chloride / catalyst (II) mixture, the reaction mixture is left under further stirring for about 0.5 to 6 hours for post-reaction and then strips out residual sulfur dioxide with nitrogen. Finally, the reaction mixture is passed to a distillation column, in which first the excess thionyl chloride and then, preferably under vacuum, the phthaloyl chloride distilled off.
• the desired catalyst (II) is added thereto with stirring.
• the addition of thionyl chloride or phosgene is started, the rate of addition being generally adjusted in such a way that the unreacted thionyl chloride or phosgene boils gently under reflux.
• reaction mixture After completion of the addition of the chlorinating agent, the reaction mixture is left under further stirring for about 0.5 to 6 hours for post-reaction and then strips residual sulfur dioxide or carbon dioxide with nitrogen out. Finally, the reaction mixture is passed to a distillation column in which first the excess chlorinating agent and then, preferably under vacuum, the phthaloyl chloride are distilled off.
• the inventive method allows the production of high purity phthalic acid, only slightly accessible and technically readily available phthalic anhydride, thionyl chloride or phosgene as the chlorinating agent and triphenylphosphine or triphenylphosphine are used as catalyst and no, predominantly remaining in the reaction mixture by-products are formed.
• Fer ⁇ ner leads the found process even under mild temperatures and pressures to a high conversion of phthalic anhydride, a high selectivity and a high yield of phthaloyl and in particular to a high space-time yield.
• space-time yields of well above 60 g of phthaloyl chloride per liter of reaction volume and hour can be achieved.
• the valuable product phthaloyl chloride from the reaction tion mixture easily separated, the reaction mixture no danger of solid precipitation. If necessary, the catalyst (II) remaining in the bottom product during the subsequent product distillation can be recovered therefrom or disposed of together with the remaining bottom product or thermally recycled.
• the estimate is the formula
• KZA ⁇ phthaloyl chloride * reactor '* based.
• m Ph t h h aiklaredic iorid is the mass of formed phthalic acid dichloride in g, V Response or the estimated volume of technically meaningful for the specific reaction batch reactor and t is the reaction time in hours, including subsequent stirring.
• the obtained homogeneous reaction product (162 g) was first freed at 200 hPa abs (200 mbar abs) and 35 ° C of excess thionyl chloride and then distilled at 9 hPa abs (9 mbar abs) and 137 ° C.
• Examples 1 to 5 show that space-time yields in the range from 58 to 76 g / l-h can be achieved in the inventive use of thionyl chloride as the chlorinating agent and of triphenylphosphine or triphenylphosphine oxide as catalyst.
• Example 6 shows that space-time yields of well above 100 g / l-h can be achieved in the use according to the invention of phosgene as chlorination agent and of triphenylphosphine oxide as catalyst. It should again be emphasized at this point that the space-time yields according to the prior art (US Pat. No. 3,810,940 and DE-A 102 37 579) in the phosgenation of phthalic anhydride in the presence of N, N-dimethylformamide as a catalyst having 31 to 52 g / lh amount to only a fraction of the space-time yields of the method according to the invention.
• reaction effluent contained 97.9 GC area% phthaloyl chloride in addition to 2.1 GC area% unreacted phthalic anhydride, which corresponds to a yield of 97.9%.
• the estimated space-time yield was about 79 g / lh.
• Example 8 shows that a reaction temperature of 70 0 C for the reaction is unzurei ⁇ accordingly. In contrast, a very high conversion could be achieved in Example 7 at a reaction temperature of 126 ° C even in the presence of a solvent.
• Example 9 (Comparative Example)
• Example 9 clearly shows that the process conditions taught in US Pat. No. 3,810,940, including the catalyst, are absolutely unsuitable for achieving a high yield and a high space-time yield.
• reaction effluent contained only 19 GC area% phthalic acid dichloride in addition to 81 GC area% unreacted phthalic anhydride, which corresponds to a yield of only 19%.
• the estimated space-time yield was just once about 16 g / lh.
• Comparative Example 10 shows that the method according to the invention significantly depends on the type of catalyst used and, for example, a Tn-C 6 - to C 6 -alkylphosphine oxide leads to triphenylphosphine oxide to dramatically worse results.

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• 2004
  • 2004-11-26 DE DE102004057146A patent/DE102004057146A1/de not_active Withdrawn
• 2005
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