Being used for drug modification, the multi-arm single molecular weight polyethylene glycol active derivative provided herein can effectively improve the solubility, stability, and immunogenicity of the drugs, improve the absorption of the drugs in vivo, prolong the half-life of the drugs, and increase bioavailability, enhance efficacy, and reduce toxic and side effects of the drugs. A gel formed from the multi-arm single molecular weight polyethylene glycol active derivative provided herein can be used for the preparation of controlled release drugs so as to prolong the action time of the drugs, thereby reducing the number of administrations and improving patient compliance.

Provided is a method capable of yielding high-purity 1,3-butylene glycol having a very low content of a low boiling point component and a high initial boiling point, with a high recovery ratio. A reaction crude liquid containing 1,3-butylene glycol is subjected to product distillation to yield purified 1,3-butylene glycol, through dehydration including removing water by distillation and performing high boiling point component removal including removing a high boiling point component by distillation. A method for producing 1,3 butylene glycol, the method including: distilling a charged liquid having a water content of 1.2 wt.% or less in a product column for use in the product distillation under a condition of a reflux ratio of greater than 0.1; distilling off a liquid in which a low boiling point component is concentrated from above a charging plate; and extracting 1,3-butylene glycol from below the charging plate.

The present disclosure relates to the technical field of hexanediol production, and provides a production method and a production device of high-purity 1,6-hexanediol. A dipic acid and a C.sub.6 mixed alcohol are mixed to conduct esterification to obtain a product feed liquid including an adipic acid diester, and the high-purity 1,6-hexanediol is obtained through hydrogenation reduction and distillation. In addition to being used as a reaction raw material, the C.sub.6 mixed alcohol further acts as a water-carrying agent; water produced by the esterification is removed by azeotropy, thereby promoting a smooth reaction process to realize the esterification without a catalyst. The method does not need the catalyst during esterification, and the subsequent hydrogenation reduction can be directly conducted with no complicated post-treatment procedure required after the esterification. In addition, the method has simple preparation steps, recyclable C.sub.6 mixed alcohol, less wastewater production, desirable environmental protection, and high product purity and yield.

The present disclosure relates to the technical field of hexanediol production, and provides a production method and a production device of high-purity 1,6-hexanediol. A dipic acid and a C.sub.6 mixed alcohol are mixed to conduct esterification to obtain a product feed liquid including an adipic acid diester, and the high-purity 1,6-hexanediol is obtained through hydrogenation reduction and distillation. In addition to being used as a reaction raw material, the C.sub.6 mixed alcohol further acts as a water-carrying agent; water produced by the esterification is removed by azeotropy, thereby promoting a smooth reaction process to realize the esterification without a catalyst. The method does not need the catalyst during esterification, and the subsequent hydrogenation reduction can be directly conducted with no complicated post-treatment procedure required after the esterification. In addition, the method has simple preparation steps, recyclable C.sub.6 mixed alcohol, less wastewater production, desirable environmental protection, and high product purity and yield.

An improved process for the recovery of high-purity ethylene-oxide water feed streams to EO purification and MEG reaction units when both are operating in EO plants that incorporate EO Stripper bypass technology, by installing a second lights stripper to exclusively degasify the diluted EO feed to the MEG reactor, thus permitting the use of additional bypassed (gasified) EO absorbate as the diluent and resulting in a substantial increase in the total amount of EO absorbate that can bypass the EO Stripper.

An improved process for the recovery of high-purity ethylene-oxide water feed streams to EO purification and MEG reaction units when both are operating in EO plants that incorporate EO Stripper bypass technology, by installing a second lights stripper to exclusively degasify the diluted EO feed to the MEG reactor, thus permitting the use of additional bypassed (gasified) EO absorbate as the diluent and resulting in a substantial increase in the total amount of EO absorbate that can bypass the EO Stripper.

A high-purity 1,3-butylene glycol product that is colorless and odorless (or almost colorless and odorless), unlikely to cause coloration and odor over time, and/or unlikely to cause an acid concentration increase over time when the product is left in a state containing water is provided. A 1,3-butylene glycol product containing 1,3-butylene glycol, wherein, after the 1,3-butylene glycol product has been kept at 180° C. for 3 hours in air atmosphere, at least one of contents of compounds represented by the following Formula (A) or (B) is less than 8 ppm. In the following formula, R.sup.1 to R.sup.4 are the same as or different from each other, and each of R.sup.1 to R.sup.4 is a hydrogen atom, an alkyl group which has from 1 to 4 carbon atoms and may be substituted with a hydroxy group, or an alkenyl group which has from 2 to 4 carbon atoms and may be substituted with a hydroxy group.

A method for producing neopentyl glycol comprising a step of perforning a hydrogenation reaction by injecting a hydroxypivaldehyde (HPA) solution and hydrogen into a hydrogenation reactor, and a step of adjusting the content of H.sub.2O contained in the hydroxypivaldehyde solutionto 6.0% by weight or less before the hydroxypivaldehyde solution being injected into the hydrogenation reactor.

A method for producing neopentyl glycol comprising a step of perforning a hydrogenation reaction by injecting a hydroxypivaldehyde (HPA) solution and hydrogen into a hydrogenation reactor, and a step of adjusting the content of H.sub.2O contained in the hydroxypivaldehyde solutionto 6.0% by weight or less before the hydroxypivaldehyde solution being injected into the hydrogenation reactor.

Provided is a polycarbonate polyol used as a raw material of a polyurethane that has an excellent balance of flexibility, mechanical strength and solvent resistance. The polycarbonate polyol includes structural units derived from a polyhydric alcohol and has a hydroxyl value of 20 to 450 mg KOH/g. The polyhydric alcohol includes: a diol (A) containing not less than 70% by weight of a specific oxyalkylene glycol (A1); and a trihydric to hexahydric branched alcohol (B) having 3 to 12 carbon atoms. In the polycarbonate polyol, structural units derived from the branched alcohol (B) is contained in an amount of 0.005 to 5.0% by mole in the structural units derived from the polyhydric alcohol. A ratio of a structural unit (X1) represented by the following Formula (X1) in the structural units derived from the branched alcohol (B) is not higher than 50% by mole. ##STR00001##