Chromatography of glycols. Regularities in the retention of C3−C6 branched glycols in gas-solid and gas-liquid chromatography

Summary Linear correlation between the major physico-chemical properties of glycols and their relative retention volumes measured by gas-solid (GSC) and gas-liquid (GLC) chromatography is shown. The coefficients of the linear regression equations describing the relationship between the relative retention volumes and the physico-chemical parameters (boiling point, density, etc.) are given. The values of the change in the free energy for the stationary phases studied are given as well as the increments of this change per −CH₂- and CH₃-group. The main factors determining the retention of branched glycols on Polysorb, Tween and poly(ethylene glycol) are shown to be the distance between the hydroxyl groups in their molecules, the presence of alkyl substituents and the type and the number of these substituents.     

DIBUTYLTIN DILAURATE-CATALYZED DIISOCYANATE COUPLING- GRAFTING OF POLY(ETHYLENE GLYCOL) ONTO NANO-SILICA SURFACE THROUGH A ONE-STEP PROCEDURE

Grafting polymer glycols onto nano-silica surface through one-step procedure was investigated. The major characteristic of this procedure is that all the materials and reagents (silica, PEG, TDI, DBTDL, solvent) required for grafting were added simultaneously into the reaction vessel. TDI and DBTDL were used as coupling agent and catalyst, respectively.The products were characterized by FTIR, TGA, elemental analyses and TEM, giving evidence for successful grafting of PEG. Possible mechanism of this grafting was studied and two grafting processes were proposed. The process through which the grafting proceeds depends on the reaction temperature. Effect of molecular weight of PEG on grafting was also investigated.     

Synthesis and Characterization of Surfactant PEG Macromonomers with Fluorocarbon End‐capped Groups and its Copolymers

Fluorocarbon (R_F) or hydrocarbon (R_H) end‐capped PEG macromonomers were prepared by coupling method. Several factors mat affect the synthesis were studied and optimum condition was obtained. The critical micelle concentrations (CMC) of these macromonomers were determined by fluorescence method. A new type of fluorocarbon‐containing hydrophobically modified alkali swellable/soluble copolymers were obtained by copolymerization of R_F or R_H alkyl endcapped PEG macromonomers with acrylic acid in organic solvent The preliminary researches on viscosity property of these copolymer solutions were conducted under different conditions, such as various macromonomer content in the copolymer, polymer concentration, shear rate, pH value and temperature. All the results proved that there existed a very strong hydrophobic association among hydrophobes in these copolymer solutions.     

Study on Phase‐Change Characteristics of PET‐PEG Copolymers

Polyethylene glycol (PEG) was selected as a phase‐change material (PCM) and the phase‐change fibers of its copolymers with polyethylene terephalate (PET), PET‐PEG, were successfully prepared by melt spinning. The PET‐PEG copolymers have solid‐solid phase change characteristics at 10–60°C without obvious liquid substance appearing, while PET/PEG blends will lose their phase‐change characteristics since the PEG of the blends may melt and leak under high temperature. By controlling the molecular weight and relavent proportion of PEG added, the phase‐change temperature range and the enthalpy can be adjusted.     

ISOTHERMAL CRYSTALLIZATION: THERMAL AND OPTICAL STUDY OF PEG

In this work, the solidification process and the crystal growth kinetics of polyethylene glycol 4000 (PEG4000) and polyethylene glycol 6000 (PEG6000) (molecular average weight 4000 and 6000, respectively) were characterized by thermal optical microscopy (OM) and differential scanning calorimetry (DSC). The growth rate decreased with increasing crystallization temperature. The kinetic rate constant was lower for PEG6000 than for PEG4000 (29,300 and 32,900 K², respectively). This behavior is related to the different number of folds (folding index n) of the crystal structures. From comparison of microscopy and calorimetry measurements, the kinetic rate constant values were higher by microscopy due to different melt histories, self-nucleation, and degree of entanglement.     

Oxetane synthesis via cyclisation of aryl sulfonate esters on polystyrene and PEG polymeric supports

The addition of suitably protected pentaerythritols to polymer supported sulfonyl chloride with subsequent alkoxide formation and intramolecular cyclisation to generate oxetanes is described. This convenient method for the preparation of oxetanes has several advantages over analogous solution phase reactions and the methodology is extended to the preparation and use of a novel PEG-sulfonyl chloride.     

A novel phosphate ligand used for the Rh-catalyzed hydroformylation of cyclohexene in a thermoregulated PEG biphase system

A novel phosphate ligand,tri-(methoxyl polyethylene glycol)-phosphate (TMPGPA),has been synthesized and used in the Rh- catalyzed hydroformylation of cyclohexene in a thermoregulated PEG biphase system.Under the optimized conditions, pressure=5 MPa (H_2:CO=1:1),P/Rh=10 (molar ratio),reaction time=4h and temperature=120℃,the conversion of cyciohexene and the yield of aldehyde are 99%.The catalyst retained in PEG phase can be easily separated from the organic phase containing product by simple phase separation and reused ten times without obvious loss in activity.     

强碱性条件下的相转移催化合成美多心安

以对甲氧乙基苯酚和环氧氯丙烷为原料，强碱KOH为催化剂，PEG400（聚乙二醇400）为相转移催化剂，通过醚化反应和胺化反应合成了美多心安。本工艺路线简单，原料易得，反应的整体收率达到50％。研究了不同反应条件对反应的影响。对中间体和目标产物进行了IR、^1HNMR、HPLC定性定量分析。确定了较好的合成反应条件。     

PEG6000溶液超声化学反应机理的初步研究

采用不同电功率的超声波处理了聚乙二醇(PEG6000)溶液。凝胶渗透色谱(GPC)分析超声处理后的PEG溶液发现,当超声电功率超过250W时,PEG分子量随超声波作用强度的增大而减少,随超声波作用时间的延长而增大;在电功率超过250W超声波作用下,傅立叶红外光谱(FT-IR)分析表明,组成PEG的单体没有明显改变,但是,羟基含量分析表明,PEG固体样品中的羟基含量有所减少。结合实验结果,根据高分子化学、有机化学和超声化学中相关理论对PEG超声化学反应机理进行了探讨,认为:当超声波作用于PEG溶液时,同时存在有PEG的缩水聚合反应和自由基降解反应,当频率为20-25kHz、电功率为250-600W的超声作用于PEG6000溶液时,缩水聚合反应占主导地位。