Classifications

• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C51/00—Preparation of carboxylic acids or their salts, halides or anhydrides
  • C07C51/16—Preparation of carboxylic acids or their salts, halides or anhydrides by oxidation
  • C07C51/27—Preparation of carboxylic acids or their salts, halides or anhydrides by oxidation with oxides of nitrogen or nitrogen-containing mineral acids
  • C07C51/275—Preparation of carboxylic acids or their salts, halides or anhydrides by oxidation with oxides of nitrogen or nitrogen-containing mineral acids of hydrocarbyl groups
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C2/00—Preparation of hydrocarbons from hydrocarbons containing a smaller number of carbon atoms
  • C07C2/86—Preparation of hydrocarbons from hydrocarbons containing a smaller number of carbon atoms by condensation between a hydrocarbon and a non-hydrocarbon
  • C07C2/862—Preparation of hydrocarbons from hydrocarbons containing a smaller number of carbon atoms by condensation between a hydrocarbon and a non-hydrocarbon the non-hydrocarbon contains only oxygen as hetero-atoms
  • C07C2/867—Preparation of hydrocarbons from hydrocarbons containing a smaller number of carbon atoms by condensation between a hydrocarbon and a non-hydrocarbon the non-hydrocarbon contains only oxygen as hetero-atoms the non-hydrocarbon is an aldehyde or a ketone
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C51/00—Preparation of carboxylic acids or their salts, halides or anhydrides
  • C07C51/54—Preparation of carboxylic acid anhydrides
  • C07C51/56—Preparation of carboxylic acid anhydrides from organic acids, their salts, their esters or their halides, e.g. by carboxylation
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C2527/00—Catalysts comprising the elements or compounds of halogens, sulfur, selenium, tellurium, phosphorus or nitrogen; Catalysts comprising carbon compounds
  • C07C2527/02—Sulfur, selenium or tellurium; Compounds thereof
  • C07C2527/053—Sulfates or other compounds comprising the anion (SnO3n+1)2-
  • C07C2527/054—Sulfuric acid or other acids with the formula H2Sn03n+1

Definitions

• This invention relates to a novel process for preparing 3,4,3',4 , -benzophenonetetracarboxylic dianhydride (BTDA) which comprises condensing an impure ortho-xylene mixture with acetaldehyde in contact with an acid catalyst to obtain an impure 1,1-bis (3,4-dimethylphenyl)ethane (DXE) mixture oxidizing the DXE mixture with nitric acid to obtain a mixture of carboxylic acids from which by crystallization and dehydration substantially pure BTDA is recovered.
• BTDA 3,4,3',4 , -benzophenonetetracarboxylic dianhydride
• ortho-Xylene as well as other isomeric xylenes, are readily obtained from petroleum crudes through catalytic reforming or cracking as part of a C 8 aromatic stream.
• a typical C 8 aromatic distillate fraction from a refinery stream has the following composition:
• a C 8 aromatic distillate fraction as defined in Table I, is separated into relatively pure components using a combination of molecular sieve adsorption, fractionation and isomerization steps.
• para-xylene and ethylbenzene are sorbed, leaving a raffinate of ortho- and meta-xylene.
• the sorbed components are desorbed with diethylbenzene, which is recovered by fractionation and ethylbenzene is separated from para-xylene in a second adsorption step.
• the sorbed para- xylene. is desorbed with toluene, which is recovered by fractionation.
• the raffinate from each of the adsorption steps contain desorbent, which is recovered by fractionation.
• the ortho- and meta-xylene mixture is isomerized to obtain additional para-xylene and the isomerizate is fractionated to remove light ends and to recover a crude ortho-xylene fraction.
• a typical crude ortho-xylene fraction so obtained will have the following composition:
• the crude (or impure) ortho-xylene fraction so recovered requires no further purification for the synthesis of phthalic anhydride, since the other components present which are not converted to phthalic anhydride are degraded during the vapor phase oxidation to carbon dioxide and water.
• an ortho-xylene fraction of higher purity for example, greater than 99 per cent, typically 99.7 per cent or better, the crude fraction is subjected to further distillation under more closely controlled and more efficient conditions involving additional expense.
• the three isomers so obtained are next to impossible to separate from each other either at the hydrocarbon stage or after oxidation with nitric acid to acids. Therefore, after dehydration, an isomeric mixture of dianhydrides is obtained.
• the dianhydride product so produced to be a low-melting solid, having a melting point around 150°C., with the various dianhydride isomers exhibiting varying degrees of reactivity, and the properties of polymers produced therefrom, particularly polyimides, to be unacceptable.
• Equation I is only about 98 to 99 per cent efficient, the net loss of condensation product would be on the order of 11 to 12 per cent. This would then make this reaction as in ⁇ efficient as if the DXM mixture defined above, produced by the reaction of substantially pure ortho-xylene and formaldehyde, had been used in the process for producing BTDA.
• the resulting mixture is main ⁇ tained at a temperature of about 5° to about 60°C, prefer ⁇ ably about 10° to about 30°C, and a pressure of about 0 to about 200 pounds per square inch gauge (about atmospheric to about 13.6 kilograms per square centimeter), preferably about atmospheric pressure, for a period of about five minutes to about five hours, preferably about five minutes to about 60 minutes.
• aqueous phase is separated from the organic phase, for example, by decanta-tion and the organic phase is neutralized, for example, using aqueous sodium hydroxide.
• the organic phase is then subjected to distillation to strip off unreacted ortho-xylene there ⁇ from, followed by distillation of the desired DXE mixture used herein.
• the nitric acid oxidation of a DXE mixture is also old and well known, as for example, in U.S. Patent No. 3,078,279 to McCracken et al.
• the DXE product obtained above is subjected to oxidation with nitric acid having a concentra-tion of about 5 to about 70 per cent, preferably about 20 to about 40 per cent.
• the amount of nitric employed, determined as the molar ratio of 100 per cent nitric acid relative to the total components in the charge, is about 8.0 to about 17.0, preferably about 8.0 to about 12.
• the residence time re-quired for the oxidation can be from about one minute to about 48 hours, preferably about 10 minutes to about two hours.
• the reaction product is permitted to cool down, preferably to room temperature, until a solid crystalline precipitate is formed. This may require, for example, from about 4 to about 24 hours.
• the crystals so obtained, substantially pure BTA, are separated from the liquid in any convenient method, for example, filtration.
• the dehydration of BTA to BTDA is also known, as for example, in said U.S. Patent No. 3,078,279.
• the BTA crystals can be dehydrated, for example, at a temperature of about 110° to about 320 o C, preferably about 150° to about 280oC., in a vacuum oven for about one-half to about 24 hours, preferably about one to about 16 hours to obtain the sub-stantially pure BTDA.
• the autoclave was sealed, heated to 140°C, at which point 720 grams of 54 per cent aqueous nitric acid was introduced over a period of three hours and then an additional 720 grams of 54 per cent aqueous nitric acid over a period of one hour. The temperature was then raised to 175°C. and an additional 720 grams of 54 per cent aqueous nitric acid was added over a period of one hour. The reaction was continued for an addition-al hour after the last addition of nitric acid.
• the pressure relief device was arbitrarily set to maintain a pressure below 1000 pounds per square inch gauge (68 kilograms per square centimeter) during the reaction.
• the autoclave was cooled to atmospheric (ambient) temperature, depressured to atmospheric pressure and the completely homogeneous solution (pale yellow in color) was withdrawn.
• a weighed one-half gram sample of the product solution was taken to dryness in a rotary evaporator and analyzed by gas liquid chromatography for the BTA con ⁇ tent. From this data the analytical yield of the product was determined.
• the total filtrate was allowed to stand undis ⁇ turbed for three hours, resulting in the crystallization of solids. Filtration, washing with a minimum amount of water and drying in a vacuum oven at 75°C. for six hours resulted in the recovery of 390 grams of BTA, corresponding to a yield of 73 per cent..
• Example II Example I was repeated except that 354 grams of the impure ortho-xylene mixture defined in Table III was used in place of the substantially pure ortho-xylene of Example I.
• Example II was repeated except that at the end of the third addition of nitric acid the reaction was continued for an additional two hours instead of one hour.
• Example II was repeated using 354 grams of aromatic feed containing 88 weight per cent of DXE, (derived from 95 weight per cent ortho-xylene) seven weight per cent ortho-xylene and five weight per cent of compounds boiling higher than DXE.
• the BTA isolated via crystallization amounted to 320 grams (76 per cent yield) .
• One-third of the total nitric acid was added at 140°C. over 3.7 hours and the remaining two-thirds at 175°C. over 1.75 hours. Reaction was stopped after holding for one hour under final conditions.
• Example V shows the unexpected results obtained operating in accordance with the process defined and claimed herein.
• Example I wherein a substantially pure ortho-xylene was used the desired BTA, precursor for BTDA, was obtained in 73 per cent yield.
• Example II, III and IV wherein an impure ortho-xylene mixture was used in an otherwise identical process, the yields were practically identical to the yield obtained in Example I.
• EXAMPLE V In order to determine whether or not the BTDA produced herein would be just as acceptable commercially as BTDA prepared from analytical grade ortho-xylene, it was deter ⁇ mined to carry out the highly-sensitive polyimide test. Accordingly, a sample of the BTA produced in Example II was melt dehydrated in a vacuum oven at 270°C. for one hour to obtain BTDA. A polyimide film was prepared from the resulting BTDA and tested as follows.
• a solution of 10.0 g. (0.05 mol) of 4, 4 '-diaminophenyl- ether in 115 cc. of water-free dimethylacetamide was prepared in a 250 cc. flask fitted with a stirrer, powder addition apparatus and a glass tube for sample removal for measurement of viscosity. The flask was closed to the atmosphere to exclude moisture. Over a two hour period 16.4 g. (0.0509 mol) of powdered BTDA was added with stirring. There was an exothermic reaction but the temperature was maintained below 40°C. by the controlled addition of the dianhydride to avoid conversion of polyamic acid to polyimide. The viscosity of the solution increased to Gardner K at the end of the reaction. The solution contained about 20 weight per cent polyamic acid.
• a film of this solution was cast on sheet Mylar (polyethylene terephthalate) using a Bird applicator set at 10 mils (0.25 mm.) .
• the film was dried one-half hour at 150 o C., in a circulating air oven.
• the resulting self-supporting film was stripped from the Mylar and was placed on a metal plate with metal strips holding the film in place.
• the final cure was completed step-wise from 200° to 300°C. by increasing the temperature over a period of about one hour with 300°C. maintained for one-half hour.
• the resulting film of about 1 mil (0.025 mm.) thickness was clear, yellow and transparent.

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• Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Engineering & Computer Science (AREA)
• Oil, Petroleum & Natural Gas (AREA)
• Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
• Furan Compounds (AREA)
• Macromolecular Compounds Obtained By Forming Nitrogen-Containing Linkages In General (AREA)

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• 1978
  • 1978-07-03 US US05/921,571 patent/US4173573A/en not_active Expired - Lifetime
• 1979
  • 1979-05-25 JP JP50091879A patent/JPS55500471A/ja active Pending
  • 1979-05-25 WO PCT/US1979/000367 patent/WO1980000149A1/en not_active Ceased
  • 1979-06-06 EP EP79301079A patent/EP0007694B1/en not_active Expired
  • 1979-06-06 DE DE7979301079T patent/DE2965134D1/de not_active Expired
  • 1979-06-25 CA CA000330492A patent/CA1117959A/en not_active Expired
  • 1979-06-29 MX MX178305A patent/MX152459A/es unknown

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