E.i. Dupont De Nemours and Company

Suriyanarayan Dorai

James Arnold Schultz

Willard L Quon

Gary A Hida

Frank L Rawling, Jr

Gerfried Pruckmayr

Melvin Charles Baker

Kirk Matthew Schall

Marianne Marsi

Donald Truszkowski

An improved method for manufacturing diesters of polytetramethylene ethers involving the polymerization of tetrahydrofuran (THF) optionally with one or more comonomers (e.g., 3-methyl THF, ethylene oxide, propylene oxide, or the like) utilizing a solid acid catalyst (e.g., Nafion.RTM.) and a carboxylic acid with carboxylic acid anhydride (e.g., acetic acid with acetic anhydride) as molecular weight control agents wherein setting the pressure of the reactor while simultaneously achieving removal of the heat of reaction by operating under solvent/monomer evaporative reaction conditions effectively controls the reaction temperature. Such a process is useful in producing high purity commercial grade PTMEA that advantageously avoids problems caused by the high heat of reaction when such a process is scaled up to commercial level.

Method for manufacturing diacetate esters of polytetramethylene ethers

A method for converting the diester of a polyether polyol (e.g., the diacetate ester of polytetramethylene ether, PTMEA) to a corresponding dihydroxy polyether polyol (e.g., polytetramethylene ether glycol, PTMEG) involving reactive distillation wherein a diester of polyether polyol is fed to the top portion of the column along with an effective amount of at least one alkali metal oxide or alkaline earth metal oxide, hydroxide or alkoxide catalyst (e.g., sodium methoxide) and with a C.sub.1 to C.sub.4 alkanol (e.g., methanol) while simultaneously adding to the bottom of the reactive distillation column hot alkanol vapor to sweep any alkanol ester formed by alkanolysis of the diester of polyether polyol upwardly. Such a process is useful for achieving high levels of conversion PTMEA to PTMEG on a commercial scale with the overhead from the column being amenable to azeotropic separation of the methyl acetate and recycle of the methanol.

Alkanolysis of polyether polyol esters by reactive distillation

An improved method for recovering purified diesters of polytetramethylene ethers involving the polymerization of tetrahydrofuran (THF) optionally with one or more comonomers (e.g., 3-methyl THF, ethylene oxide, propylene oxide, or the like) utilizing a solid acid catalyst (e.g., Nafion.RTM.) and a carboxylic acid with carboxylic acid anhydride (e.g., acetic acid with acetic anhydride) as molecular weight control agents wherein after polymerization product recovery involves bulk flashing of unreacted THF and stripping of remaining THF, carboxylic acid and carboxylic acid anhydride (e.g., acetic acid and acetic anhydride) by use of superheated THF. Such a process is useful in producing high purity commercial grade PTMEA that advantageously avoids problems associated with the presence of high boilers when converting to PTMEG.

Method for recovering diacetate esters of polytetramethylene ethers

Polyether glycols, especially poly(tetramethylene ether) glycol (PTMEG) having a narrow molecular weight distribution of about 1.25 to 1.80, or dispersity of 1.05 to 1.90, are made by a process involving distilling the low molecular weight fraction in unit operations including at least one short-path distillation evaporator. Two short-path distillation evaporators, in series, are desirable if significant narrowing of the PTMEG is required. In these units, PTMEG is subjected to temperatures in the range of 270.degree.-400.degree. C. with the hold-up time varying between 10-200 seconds. The required vacuum to force the separation of the low molecular weight PTMEG varies between 0.001 mm and 1.0 mbar. PTMEG residue from the distillation unit is also characterized by its low water content and low concentration of oligomeric cyclic ethers.

Reducing molecular weight distribution of polyether glycols by

Polyether glycols, especially poly(tetramethylene ether) glycol (PTMEG) having a narrow molecular weight distribution of about 1.90 to 2.07, or dispersity of 1.50 to 1.90, are made by a process wherein the low molecular weight fraction in unit operations using at least one short-path distillation evaporator. In these units, PTMEG is subjected to temperatures in the range of 150.degree.-190.degree.C. with the hold-up time varying between 10-200 seconds. The required vacuum to force the separation of the low molecular weight PTMEG varies between 0.001 mm and 1.0 mbar. PTMEG residue from the distillation unit is also characterized by its low water content and low concentration of oligomeric cyclic ethers.

A process for reducing the molecular weight of polytetramethylene ether glycol without significant conversion of polytetramethylene ether glycol to tetrahydrofuran monomer is disclosed. The process involves a two-step procedure. The first step comprises reacting polytetramethylene ether glycol with a perfluoroalkyl carboxylic acid to form a perfluoroalkyl ester of polytetramethylene ether glycol. That ester is, in the second step, converted back to polytetramethylene ether glycol of reduced molecular weight by hydrolysis or alcoholysis.

Reduction of molecular weight of poly(tetramethylene ether) glycol

A process for forming polytetramethylene ether glycol having a number average molecular weight of 600 to 2,200 by contacting tetrahydrofuran with 5 to 50 wt %, based on tetrahydrofuran, trifluoromethane sulfonic acid monohydrate and water at 20.degree. to 75.degree. C. is disclosed.

Polymerization of tetrahydrofuran using trifluoromethane sulfonic acid

A process for polymerizing tetrahydrofuran to produce polytetramethylene ether glycol or ester-capped polytetramethylene ether glycol is disclosed. The reaction mass is carried out at 10.degree. to 80.degree. C. and preferably 20.degree. to 60.degree. C. In a preferred aspect of the invention, a mixture of acetic anhydride and acetic acid is present in the reaction mixture.

Preparation of polytetramethylene ether glycol using an acidic zirconia

A process for polymerizing tetrahydrofuran using a fluorinated resin containing sulfonic acid groups a trifluoromethane sulfonic acid as catalyst and a mixture of maleic acid and maleic anhydride as weight control agent. The product has the formula ##STR1## which can be hydrogenated to produce polytetramethylene ether glycol. The preferred molecular weight range of the polytetramethylene ether glycol is 600 to 4,000.

Polymerization of tetrahydrofuran using a fluorinated acidic catalyst

A catalyst and process for preparing it and its use in polymerizing tetrahydrofuran to produce polytetramethylene ether glycol ether are disclosed. The catalyst is a blend of a fluorinated resin containing sulfonic acid groups and a fluorinated resin containing carboxylic acid groups. The catalyst is partially dried to contain from 1,000 to 2,000 ppm water, so that when it is used to polymerize tetrahydrofuran, the product polytetramethylene ether glycol will have a number average molecular weight of from 250 to 4,000.

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Lockport, NY, United States of America

Suriyanarayan Dorai