Classifications

• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C67/00—Preparation of carboxylic acid esters
  • C07C67/10—Preparation of carboxylic acid esters by reacting carboxylic acids or symmetrical anhydrides with ester groups or with a carbon-halogen bond
  • C07C67/11—Preparation of carboxylic acid esters by reacting carboxylic acids or symmetrical anhydrides with ester groups or with a carbon-halogen bond being mineral ester groups

Definitions

• U.S. Patent 3,413,336 refers in its introduction broadly to a number of known processes which it regards as presenting various difficulties.
• column 1, lines 55-61 it states: "It is also known to prepare aromatic dicarboxyl ic acid aryl esters by reacting the carboxylic acids with diaryl carbonates in the presence of catalysts. However, the process does not eliminate working with acid chlorides, since phosgene must be used in the preparation of the' diaryl carbonates.” It is to be noted that no specific reagents (other than phosgene), proportions, conditions, catalyst, or specific process is disclosed.
• the subject invention provides an improved and simplified process, which requires only a short reaction time, and which results in high yields of diphenyl isophthalate and diphenyl terephthalate in a purified state.
• the invention has a decided advantage over other processes used to produce diphenyl isophthalate and diphenyl terephthalate such as those which employ acid chlorides, those which employ phenyl acetates, and those which employ aromatic hydrocarbons such as ethyl benzene and xylene.
• diphenyl isophthalate and diphenyl terephthalate can be readily prepared by heating isophthalic acid or terephthalic acid with diphenyl carbonate in the presence of stannous oxide (SnO) as the catalyst at an elevated temperature of from about 250oC. to about 300°C. for about 30 minutes to at most about 2.5 hours depending on the temperature employed, removing the phenol formed in the resulting reaction during the heating period at atmospheric pressure, removing the excess diphenyl carbonate under vacuum, and recovering the diphenyl isophthalate or diphenyl terephthalate.
• SnO stannous oxide
• diphenyl carbonate any amount can be used, it is preferred to use at least a stoichiometric amount.
• An especially preferred mole ratio of diphenyl carbonate employed in the subject process to the isophthalic acid and terephthalic acid will range from about 6:1 to 3:1. Theory calls for a molar ratio of 2:1 and the process can be carried out at this ratio but yields and purity are lower when ratio is 2:1 or less.
• the stannous oxide (SnO) is employed in a catalytic amount, ranging from about 0.25 to about 0.5 mole percent based on the moles of isophthalic acid or the terephthalic acid employed.
• vacuum is preferably at about 1 mm. pressure.
• the removal of any excess diphenyl carbonate is preferably done by distillation at about 1 mm. at a temperature of about 140-180°C, and the diphenyl isophthalate and diphenyl terephthalate are preferably recovered by distillation at about 1 mm. at a temperature of about 250-270°C.
• the present invention relates to an improved process of producing diphenyl isophthalate and diphenyl terephthalate from isophthalic acid and terephthalic acid by reacting either of the aforesaid acids under certain conditions and recovering the aforesaid esters.
• isophthalic acid or terephthalic acid (1 mole), diphenyl carbonate (3 moles), and stannous oxide
• EXAMPLE 1 232 grams (1.08 moles) of diphenyl carbonate, 30 grams (0.18 mole) of isophthalic acid and SnO (0.12 grams, 0.5 mole percent based on the isophthalic acid) are charged into a 500 ml. flask equipped with a nitrogen inlet, mechanical stirrer, and distillation column. The mixture is heated to 280°C. for two hours under nitrogen sparge while removing the phenol formed in the reaction. During the heating period the phenol is removed at atmospheric pressure. The mixture is then distilled at 1 mm. pressure at 140°C. for removal of excess diphenyl carbonate and at 1 mm. pressure at 250°C. for recovery of diphenyl isophthalate.
• EXAMPLE 2 232 grams (1.08) moles of diphenyl carbonate, 30 grams (0.18 mole) of terephthalic acid and SnO (0.12 grams, 0.5 mole percent based on the terephthalic acid) are charged into a flask as described and equipped in Example 1. The mixture is heated to 280-290°C. for two hours under nitrogen sparge while removing the phenol formed in the reaction. During the heating the phenol is removed under atmospheric pressure. The mixture is the distilled at 1 mm. pressure at 140°C. to remove excess diphenyl carbonate, and at 1 mm. pressure at 250°C. to recover the diphenyl terephthalate. Substantial formation of diphenyl terephthalate is already evident after heating for 30 minutes.

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• Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)

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• 1981
  • 1981-07-07 WO PCT/US1981/000914 patent/WO1982000290A1/en not_active Ceased
  • 1981-07-07 JP JP56502531A patent/JPS57501032A/ja active Pending
  • 1981-07-14 EP EP19810105519 patent/EP0044509B1/en not_active Expired
  • 1981-07-14 DE DE8181105519T patent/DE3163979D1/de not_active Expired

Patent Citations (4)

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