Abstract: Provided is a process for producing a plasticizer ester characterized by previously removing dissolved oxygen in a starting alcohol, and then subjecting an organic acid or its anhydride and the alcohol to an esterification reaction in the presence of an organic metal compound catalyst, which process can substantially reduce formation of coloring impurities and can easily provide a plasticizer ester having a low degree of coloring.Further, a plasticizer ester having a high volume resistivity can easily be obtained by adding an alkaline aqueous solution to a reaction product obtained by an esterification reaction to conduct neutralization of an unreacted acid and hydrolysis of the catalyst, further blowing a carbon dioxide gas to convert the residual alkali into a carbonate, recovering an excess alcohol, and then conducting purification through finefiltration using a filter aid or further in combination with adsorption treatment.

Abstract: A process for preparing crude dimethyl terephthalate, comprises oxidizing a mixture comprising para-xylene and methyl para-toluate, esterifying the oxidized mixture with methanol, separating the resulting crude ester into fractions. By separating the crude ester with a distillation column containing structured packing and using a lower bottom temperature, product yield is increased, and the process is made more economical.

Abstract: There is described a process for depolymerizing polyesters such as polyethylene terephthalate polyester to monomer components comprising esters such as dimethyl terephthalate and purifying the ester by sublimation, which purified ester can then be used to make virgin polyester.

Abstract: Processes for recovering 4,4'-dimethyl bibenzoate (DMBB) from byproduct streams of dimethyl terephthalate (DMT) production are disclosed. The byproduct streams are treated to produce an overhead stream which includes DMBB. In one aspect of the invention, the overhead product stream is added to an organic solvent under conditions sufficient to rapidly form a suspension of crystallized DMBB. In another aspect of the invention, the overhead is dissolved in an appropriate organic solvent and cooled to form a suspension of DMBB crystals in the solvent. A portion of the suspension is removed, and the remaining portion of the suspension centrifuged to recover DMBB crystals. In still another aspect of the invention, the overhead stream is treated with an organic solvent to form a slurry of DMBB crystals, and the resultant slurry thermally treated to increase the concentration of DMBB crystals therein while also solubilizing any organic contaminants.

Abstract: A process for the preparation of dialkyl tetrahalophthalates. A tetrahalophthalic anhydride or acid is dissolved in excess C.sub.1 -C.sub.18 alkanols. Residual sulfuric acid is removed by treatment with magnesium acetate or multiple water washes. The mass is esterified with a tetraalkyl titanate, and residual acidic components are removed by treatment with magnesium silicate. These treatments improve processability, production cycle time, product color, clarity and purity.

Abstract: There is described a process for depolymerizing polyethylene naphthalate polyester to monomer components which then can be used to make virgin polyester.

Abstract: An improved process for recovering depolymerization products from polymers such as polyesters, polyamides, and polyesteramides, especially when the starting polymer content is less than about 98%. The depolymerization and vapor phase recovery of monomers and other reaction products are conducted in the presence of a solid support.

Abstract: There is described a process for improving the yield of difunctional ester in a process of recovering monomer components from condensation-type polyester resins such as polyethylene terephthalate by converting terephthalyl monomers and oligomers present in ethylene glycol still bottoms to terephthalate diester, such as dimethyl terephthalate. This is accomplished by treating the terephthalyl monomers and oligomers with a mixture of an alcohol and an alkali metal hydroxide at a temperature up to the boiling point of the alcohol.

Abstract: There is described a process for the depolymerization of polyethylene terephthalate into component monomers at ambient pressure. Monomer solids that deposit during cooling, as part of the recovery operation, are removed using a scraped wall heat exchanger.

Abstract: A process for working up, by methanolysis, a residue fraction resulting from raw ester distillation in a DMT process is provided, the process involving:admixing the residue fraction with liquid or gaseous methanol, or both to give a reaction mixture;providing the reaction mixture to a reactor, wherein, prior to entry into the reactor, the reaction mixture is at a temperature of from 230.degree. to 265.degree. C.; andmethanolysing the reaction mixture in the reactor, wherein a bottom portion of the reactor is maintained at a temperature of from 230.degree. to 265.degree. C.

Abstract: Carboxylate protective groups, a process for their preparation, their coupling to a funcitonal group, and their useCarboxylates of polar, hydrophilic alcohols of the formula ##STR1## in which R is an unbranched or branched organic radical which contains, as polar members between aliphatic or araliphatic hydrocarbon bridges, ether oxygens, amine nitrogen groups or a mixture of ether and amine groups which can be incorporated into a cyclic structure, where the total length does not exceed 20 members and where, in the case of polyethylene glycol [(CH.sub.2 --CH.sub.2 --O).sub.n ], n indicates the number of the members and is defined as any integer, andR' is an aliphatic or araliphatic radical which has at least one functional group,are suitable as protective groups since they can be introduced selectively into functional groups of organic compounds and eliminated specifically by lipases.

Abstract: A method of removing dimethyl terephthalate (DMT) from a vapor stream. The vapor stream includes dimethyl terephthalate (DMT), methylhydroxyethyl terephthalate (MHET), glycols and methanol. A distillation column is held under an elevated pressure of 100 to 500 kPag and at a temperature of at least 85.degree. C. It has (i) a plurality of distillation trays; (ii) methanol liquid sprays between the trays; (iii) a main spray zone below the trays and (iv) a liquid pool of methanol in the bottom of the column. The vapor stream is directed into the distillation column, above the liquid pool and below the main spray zone, thereby forming a stream of liquid and vapor. The stream of liquid is directed away from the distillation column walls and into the liquid pool at the bottom of the column.

Abstract: There is described a process for the depolymerization of polyethylene terephthalate into component monomers using a reactor in which the polyethylene terephthalate is a discontinuous phase which contacts a continuous phase of superheated methanol vapor.

Abstract: An improved method for recovery of alkali metal or alkaline-earth metal terephthalate and of alkylene glycol, from polyalkylene terephthalate, in particular from polyethylene terephthalate (P.E.T.), alkylene glycol, in particular ethylene glycol produced in the form of vapor during the saponification reaction, initiated by the action of intensive kneading of polyalkylene terephthalate and the alkaline reagent at a temperature of 100.degree. to 200.degree. C. The alkylene glycol is recovered in gaseous form by entrainment by an inert gas or by extraction under low pressure. The alkaline terephthalate or alkaline-earth terephthalate is obtained in solid or powder form; it can easily be stored, transported and redissolved, in order to be purified and possibly transformed into terephthalic acid or ester.

Abstract: An improved process for recovering reaction products from polymers such as polyesters or polyamides, especially those having a desired polymer level below about 98%. The process involves depolymerization and vapor phase extraction of monomers in the presence of a solid support.

Abstract: A process for recovering dimethyl terephthalate (DMT) comprises the steps of: providing a dimethyl terephthalate stream including dimethyl terephthalate, glycols, and coordination compounds; acidifying the coordination compounds to disassociate the ligands from the metalions; separating the ligands from the metalions; separating the dimethyl terephthalate from the glycols; and recovering the dimethyl terephthalate. Additionally, the process may include the step of basifying the metalions to precipitate the metal; and recovering the metal.

Abstract: Provided is a method useful for separating and removing impurities such as cyclohexane dimethanol (CHDM) and other additives from their mixture with dimethylterehthalate (DMT), formed during a depolymerization process such as methanolysis of poly(ethyene terephthalate) (PET), poly(cyclohexyldimethylene terephthalate) (PCT), or copolyers of PET and PCT. The separation and removal of CHDM is accomplished via either melt or solution crystallization of the DMT following excess methanol removal (via distillation) of the methanolysis reactor products.

Abstract: The invention relates to a novel process for the preparation of terephthalic diesters and diols from polyesters. The process comprises depolymerization of the polyester in the presence of transesterification catalysts for said polyester and in the presence of an ester and subsequent transesterification of the reaction mixture to give the terephthalic diester by reaction with a monohydric alcohol. The novel process allows the starting components of polyesters to be recovered rapidly and under mild reaction conditions.

Abstract: Heating of polyvinyl chloride, in particular plasticizer-containing polyvinyl chloride, to a temperature of from 250.degree. to 500.degree. C. in the absence of oxygen gives a low-chlorine, carbon-containing residue, plasticizer and hydrogen chloride.

Abstract: A process for the titanate catalyzed preparation of plasticizers from polycarboxylic acids and alcohols which minimizes waste water and is energy efficient. The reaction product is treated with aqueous caustic and is then filtered using an absorbent medium which removes titanium, caustic, acid salts and water. The need for water washing is obviated, and the final plasticizer product has excellent properties.

Abstract: A method for recovering dimethyl naphthalene-2,6-dicarboxylate (DMN) from a mixture of dimethyl naphthalene-2,6-dicarboxylate (DMN) and dimethyl terephthalate (DMT), which comprises recrystallizing said mixture in a mixed medium of ethylene glycol and methanol, said mixed medium containing 10 to 60% by weight of ethylene glycol, and separating precipitated dimethyl naphthalene-2,6-dicarboxylate (DMN). According to this invention, DMN can be recovered with high yield from a mixture of DMN and DMT which is obtained from depolymerization of a mixed polymer of polyethylene-2,6-naphthalenedicarboxylate and polyethylene terephthalate.

Abstract: There is described a process and optimal conditions for depolymerizing polyester into its components and separating the components using apparatus comprising:a dissolver for receiving polyester,a reactor for depolymerizing polyester into components, anda rectifier for separating polyester components; the process comprising the steps of:a) adding polyester to the dissolver and combining it with melt from the reactor and liquid from the rectifier to reduce the chain length of the polyester,b) transferring reduced chain length polyester from the dissolver to the reactor,c) passing super-heated methanol through the reactor to depolymerize polyester into its constituent monomers;d) transferring depolymerization products from the reactor to the rectifier; ande) separating the depolymerization products in the rectifier into a vapor phase containing component monomers and a liquid phase containing higher molecular weight materials.

Abstract: A process for recycling by-products produced from a process for the manufacture of polyethylene terephthalate is disclosed. The process includes the steps of: (a) providing ethylene glycol distillation bottoms from an ethylene glycol recovery unit associated with the manufacture of polyethylene terephthalate, the bottoms containing an alkali metal organic salt produced during the manufacture of polyethylene terephthalate, the alkali metal organic salt being in excess of about 100 ppm of the bottoms; (b) stripping the alkali metal from the organic acid by use of a strong acid; and (c) depolymerizing the organic acid.

Abstract: A process useful for the recovery of terephthalic acid and ethylene glycol from poly(ethylene terephthalate) or its copolymers. The process is economical, beneficial to the environment and provides polymer grade terephthalic acid and ethylene glycol from post-consumer resin. The process is a six-step process including: (1) contacting a resin containing poly(ethylene terephthalate) with water at elevated temperature and pressure, (2) cooling the resulting mixture to provide a solid portion containing terephthalic acid and a liquid portion containing ethylene glycol, (3) recovery of the ethylene glycol from the liquid portion by distillation, (4) recovery of the terephthalic acid by heating the solid portion in the presence of water vapor at elevated temperature to produce a vapor containing terephthalic acid and water, (5) cooling terephthalic acid water vapor mixture to a temperature below the dew point of terephthalic acid and (6) collecting the polymer grade terephthalic acid.

Abstract: A process for recovering dimethyl terephthalate (DMT) is disclosed. The process includes the steps of: (a) providing a DMT stream, the DMT stream including DMT, catalyst, and ethylene glycol; (b) adding a solvent to the DMT stream, the solvent being immiscible with water and miscible with DMT; (c) adding water to the DMT stream; and (d) forming two phases, a first phase of the solvent and DMT, and a second phase of water, ethylene glycol, and catalyst.

Abstract: Process for isolating dimethyl 4,4'-biphenyldicarboxylate from residues of DMT production, which includes first distilling the residues at a pressure of at most 7 mbar at a boiler temperature from 200.degree. to 350.degree. C., subsequently treating the distillate which distills over in the range from 230.degree. to 270.degree. C. at a pressure of, for example, 0.2 mbar for from 10 to 60 minutes with 0.7 to 10 times the amount of an organic solvent at a temperature from 70.degree. to 180.degree. C., if required, separating the clear solution from undissolved components, cooling the removed clear solution to a temperature from 45.degree. to 65.degree. C. and allowing it to crystallize at this temperature, resulting in a suspension of dimethyl 4,4'-biphenyldicarboxylate crystals from which the crystals are isolated by washing one or more times with the same or a different solvent and by drying.

Abstract: There is described a process for avoiding dioxane formation during the depolymerization of polyester into glycol and ester components by passing superheated methanol through a reaction mixture containing polyester, oligomer and contaminants that are capable of forming sulfuric or halogen acids, the process comprising the step of adding sufficient base to neutralize any acid formed from the contaminants.

Abstract: Separation of ethylene glycol and diethylene glycol from dimethyl terephthalate is accomplished by distillation using methyl benzoate or the methyl ester of p-toluic acid as an azeotropic agent.

Abstract: Ester bonds are hydrolyzed in the conversion of substantially amorphous polyesters to their monomeric components, by being contacted with a mixture of (a) an alcohol, such as methanol, or glycol, (b) a polar aprotic solvent such as N-methyl-pyrrolidone or dimethyl sulfoxide and (c) an alkoxide or hydroxide such as sodium hydroxide.

Abstract: A process for the production of terephthalate diesters having the following formula (I). ##STR1## Substituents R and R' are the same or different and represent a straight chain, branched or cyclic aliphatic group, an aromatic group, an alkaryl group or an aralkyl group, each group having from 6 to 20 carbon atoms. The process involves reacting a terephthalate polyester with a high molecular weight alcohol or a mixture of high molecular weight alcohols each having from 6 to 20 carbon atoms, in the presence of a catalyst and recovering the desired compound according to formula (I). This process is particularly useful for recycling scrap terephthalate polyester products such as those produced from polyethylene terephthalate (PET), crystallized polyethylene terephthalate (CPET), glycol-modified polyethylene terephthalate copolyester (PETG), polybutylene terephthalate (PBT), polycyclohexanedimethylene terephthalate (PCT), as well as the acid- and glycol-modified copolyesters of PCT, respectively PCTA and PCTG.

Abstract: A process for recovering dimethyl terephthalate and ethylene glycol from a stream including aqueous ethylene glycol is described. Adding a dispersing agent to the stream renders it filterable, and a subsequent cooling of the stream containing the dispersing agent causes dimethyl terephthalate to precipitate in a form which can be removed by conventional filtration. The precipitated dimethyl terephthalate is of a quality and purity suitable for use in the manufacture of polyethylene terephthalate. A commercially valuable ethylene glycol stream is also recovered by the process.

Abstract: A process for obtaining a substantially pure enantiomer of an aryl-substituted aliphatic carboxylic acid is described. The process utilizes first an enantiomerically enriched mixture the of aryl-substituted aliphatic carboxylic acid obtained from kinetic resolution, diastereomeric crystallization or asymmetric synthesis processes. This enriched mixture is reacted with a base producing a salt that has the following properties:1) has at least one eutectic point;2) a composition that is not at the eutectic point; and3) a eutectic composition that is closer to the racemic composition than is the eutectic composition of said aryl-substituted carboxylic acid.Substantially pure, enantiomeric salt is separated, leaving a mother liquor comprising the solvent and aryl-substituted aliphatic carboxylic acid enriched in the other enantiomer.

Abstract: A process for preparing purified dimethyl-2,6-naphthalenedicarboxylate by the esterification of 2,6-naphthalenedicarboxylic acid is disclosed and which process provides for the efficient removal of the mono methyl ester of 2,6-naphthalenedicarboxylic acid produced during the esterification reaction.

Abstract: A process for preparing purified dimethyl-2,6-naphthalenedicarboxylate by the esterification of 2,6-naphthalenedicarboxylic acid is disclosed, and which process provides for the efficient removal of residual oxidation catalyst metals from the dimethyl-2,6-naphthalenedicarboxylate and efficient removal of particulate contaminants.

Abstract: A process for purifying crude 2,6-naphthalene dimethyl dicarboxylate (hereinunder referred to as 2,6-NDM) which comprises dissolving the crude 2,6-NDM into a C.sub.6 -C.sub.9 aromatic hydrocarbon, then contacting the solution of 2,6-NDM and the hydrocarbon with an hydrotalcite-like laminar crystalline compound and activated carbon, then carrying out thermal filtration of the solution, and then cooling the solution to separate 2,6-NDM crystal from the solution is disclosed.

Abstract: Acetic acid is recovered from the mother liquor used to oxidize para-xylene to terephthalic acid by adding at least one organic compound having a melting point below 140.degree. C. and an atmospheric boiling point above 230.degree. C.

Abstract: A method for stabilizing molten diesters of naphthalenedicarboxylic acids and stabilized naphthalenedicarboxylic acid diester compositions are disclosed.

Abstract: In the process for the purification of diemthyl terephthalate (DMT) by recrystallization from methanolic solution, the mother liquor containing the impurities, substantially the isomers DMI, DMO and aldehydes, is separated off and passed to a workup tank. The moist crystals are dried by melting with the evaporation of methanol. The mother liquor is then separated off by filtration, and the moist crystals obtained from the separation are washed before melting. The washing liquid is recycled together with a portion of the separated mother liquor into the recrystallization tank.

Abstract: A process for the production of terephthalate diesters having the following formula (I). ##STR1## Substituents R and R' are the same or different and represent a straight chain, branched or cyclic aliphatic group, an aromatic group, an alkaryl group or an aralkyl group, each group having from 6 to 20 carbon atoms. The process involves reacting a terephthalate polyester with a high molecular weight alcohol or a mixture of high molecular weight alcohols each having from 6 to 20 carbon atoms, in the presence of a catalyst and recovering the desired compound according to formula (I). This process is particularly useful for recycling scrap terephthalate polyester products such as those produced from polyethylene terephthalate (PET), crystallized polyethylene terephthalate (CPET), glycol-modified polyethylene terephthalate copolyester (PETG), polybutylene terephthalate (PBT), polycyclohexanedimethylene terephthalate (PCT), as well as the acid- and glycol-modified copolyesters of PCT, respectively PCTA and PCTG.

Abstract: A process for the production of aromatic esters or aromatic anhydrides with improved color properties is disclosed. This process comprises treating the aromatic ester or aromatic anhydride with an activated boric acid followed by fractionation.

Abstract: A process for the preparation of naphthalenecarboxylic acid esters in which a substituted naphthalene is oxidized with molecular oxygen in the presence of a heavy metal-based catalyst in a solvent comprising a lower aliphatic monocarboxylic acid to form a naphthalenecarboxylic acid and the resulting acid is then esterified. The esterified product is purified by washing, recrystallization, and distillation in that order. Heavy metals are recovered as carbonates from filtrates and washings obtained by seeparation of crude acid and ester products and by washing thereof.

Abstract: A method for producing an ester, which comprises reacting an organic acid or its anhydride with an alcohol in the presence of a catalyst of an organometallic compound, wherein an esterification reaction product containing the catalyst, is treated with a polyhydric alcohol.

Abstract: A process is disclosed for preparing polymeric plasticizers from polyethylene terephthalate which comprises reacting a trimellitic acid polyester ether with polyethylene terephthalate to prepare a nonlinear copolymer with hydroxyl functionality which is then reacted with a fatty acid of from 12 to 18 carbon atoms. The resulting composition has excellent properties as a polymeric plasticizer for polyvinylchloride resin.

Abstract: A method of recovering ethylene glycol and dimethyl terephthalate from scrap polyethylene terephthalate resins by dissolving the scrap in oligomers of the same monomers and passing methanol through the solution.

Abstract: A chiral two-phase system for resolution of racemic mixtures, or for separation of diastereomers, is disclosed. The system comprises two immiscible liquid phases and one or more enantioselectively binding chiral components, each of which is substantially in one of said phases.Also disclosed is a method for chiral resolution of racemic mixtures, or for separation of diastereomers. Use is here made of the fact that different enantiomers are partitioned differently between the phases in the above-mentioned two-phase system in that one of the enantiomers is selectively bound to one of the chiral components which is substantially in one of said phases.

Abstract: Solutions of crude isophthalic acid are purified by hydrogenation to provide purified isophthalic acid having a predetermined color scale b*-value or optical density.

Abstract: Solutions of crude isophthalic acid are purified by hydrogenation in the presence of a catalyst comprising two Group VIII noble metal-containing components.

Abstract: A process for the production of terephthalate esters having the following general formula (I). ##STR1## Substituents R and R' are the same or different and represent a straight chain or branched alkyl group having from 6 to 15 carbon atoms. The process comprises reacting a terephthalate polyester with a high molecular weight alcohol or mixture of high molecular weight alcohols in the presence of a catalyst and recovering the desired compound according to formula (I). This process is particularly useful for recycling scrap terephthalate polyesters such as polyethylene terephthalate and polybutylene terephthalate.

Abstract: A method for purifying a dimethyl naphthalene dicarboxylate produced from a naphthalene dicarboxylic acid which is in turn produced by the liquid phase oxidation of a dialkylnaphthalene or partially oxidized derivative thereof in the presence of a catalyst comprising a bromine-containing component and at least one of a cobalt- or manganese-containing component.

Abstract: A process for the formation and recovery of dialkyl naphthalene-2,6-dicarboxylates from poly-(alkylene naphthalene-2,6-dicarboxylate) polyesters. Alcoholysis of poly(ethylene naphthalene-2,6-dicarboxylate) in the presence of a transesterification catalyst on cooling yields solid dialkyl naphthalene-2,6-dicarboxylate which may be collected by filtration and further purified by recrystallization from xylenes. Novel alkyl hydroxyalkyl naphthalene-2,6-dicarboxylate compounds may be isolated from the filtrate and either reconverted to polyester or further alcoholized to dialkyl naphthalene-2,6-dicarboxylate.