Title of Invention: Process for the preparation of aromatic compounds containing a heterocyclic system
Abstract: Process for the preparation of aromatic compounds containing a heterocyclic system, having general formula (II): ##STR1## which comprises reacting catechol, optionally substituted, with a methylene dihalide in a basic environment and in the presence of a solvent medium consisting of N-methylpyrrolidone.
Detailed Description: Part PAR: Some illustrative but non-limiting examples are provided for a better understanding of the present invention and for its embodiment.
Part PAC: EXAMPLE 1
Part PAR_2: 650 g of NMP (6.5 moles) and 173 g of K.sub.2 CO.sub.3 (1.25 moles) are charged into a 1,000 cc reactor equipped with a stirrer, condenser and phase separator, thermometer and two distributors, one of which with a plunged pipe immersed in the reaction mixture. The suspension obtained is then heated to 130.degree. C.
Part PAR_3: At this temperature, the feeding is initiated over a period of 4.5 hours of 110.11 g (1 mole) of catechol in the molten state.
Part PAR_4: The methylene chloride is fed in continuous contemporaneously, by means of the distributor with a plunged pipe immersed in the reaction mixture, and this feeding is continued for a further two hours after the feeding of the catechol has finished and in such a quantity as to maintain an abundant reflux at the reaction temperature.
Part PAR_5: The methylene chloride, after condensation and separation of the water, is recycled in the same reaction mixture.
Part PAR_6: The total reaction time at a temperature of 130.degree. C. is about 6.5 hours.
Part PAR_7: The reaction mixture is cooled to room temperature for filtration and elimination of the filtered solid.
Part PAR_8: The solution, after filtration, is evaporated from the methylene chloride present and then distilled at reduced pressure in a rectifying column obtaining a pure fraction of MDB of 116.62 g (boiling point: 110.degree. C. at 100 torr).
Part PA1: Catechol conversion: 100%. PA1 Selectivity to MDB: 95.5%. PA1 Catechol conversion: 100%. PA1 Selectivity to MDB: 94.5%. PA1 Catechol conversion: 100%. PA1 Selectivity to MDB: 90.1%. PA1 Catechol conversion: 100%. PA1 Selectivity to MDB: 94.0%. PA1 Conversion of 4-methylcatechol: 100%. PA1 Selectivity to methylenedioxytoluene: 93.5%. PA1 Conversion of 3,4-dihydroxybenzaldehyde: 100% PA1 Selectivity to 3,4-methylenedioxybenzaldehyde: 93.5%.
Part PAC_2: EXAMPLE 2
Part PAR_9: The same procedure is carried out as in example 1, charging 1.5 moles of K.sub.2 CO.sub.3 (207 g). After filtration of the salts and distillation of the MDB, 115.4 g of pure product are obtained.
Part PAC_3: EXAMPLE 3
Part PAR_10: The same procedure is carried out as in example 2, but operating at a temperature of 120.degree. C. After distillation, 110 g of pure MDB are obtained.
Part PAC_4: EXAMPLE 4
Part PAR_11: The same procedure is carried out as in example 1, charging 1.1 moles of K.sub.2 CO.sub.3 (152 g). After filtration of the salts and distillation of the MDB, 114.79 g of pure MDB are obtained.
Part PAC_5: EXAMPLE 5
Part PAR_12: The same procedure is carried out as in example 1, charging 4-methylcatechol instead of catechol. After distillation in a stream of vapour with water, 127.3 g of pure 3,4-methylenedioxytoluene are obtained.
Part PAC_6: EXAMPLE 6
Part PAR_13: The same procedure is carried out as in example 1, charging 3,4-dihydroxybenzaldehyde in a solution of NMP instead of catechol. At the end of the reaction after separation by distillation under vacuum (residue of 10 mmHg) 141.6 g of pure 3,4-methylenedioxybenzaldehyde are obtained.
Part PAC_7: EXAMPLE 7 (COMPARATIVE)
Part PAR_14: The same procedure is carried out as in example 1 except that the NMP solvent is substituted with an equal quantity of sulfolane.
Part PAR_15: At the end of the reaction a 100% conversion is obtained but with a reduction in the selectivity to 80%.
Part PAC_8: EXAMPLE 8 (COMPARATIVE)
Part PAR_16: The same procedure is carried out as in example 1 except that the NMP solvent is substituted with an equal quantity of dimethylformamide and the temperature is reduced to 100.degree. C.
Part PAR_17: At the end of the reaction a 100% conversion is obtained but with a reduction in the selectivity to 80%.
Part PAR_18: The text and examples of the present invention have been deliberately limited to N-methylpyrrolidone as this is the most convenient and available among N-alkylpyrrolidones. Other alkyl or cycloalkyl pyrrolidones are obviously included in the scope of the present invention.


{'bibliographic_information': "{'Patent Number': '059361034', 'Series Code': '9', 'Application Number': '0709131', 'Application Type': '1', 'Art unit': '163', 'Application Filing Date': '19980504', 'Title of Invention': 'Process for the preparation of aromatic compounds containing a heterocyclic system', 'Issue Date': '19990810', 'Number of Claims': '8', 'Exemplary Claim Number(s)': '1', 'Assistant Examiner': 'Solola; Taofiq A.', 'Primary Examiner': 'Richter; Johann'}", 'source_file': './grant/1999/pftaps19990810_wk32.txt', 'source_data': 'USPTO-Grant'}