Rapid and Simple Method of Monoacylation of Polyols by β‐Ketoesters Using Microwave Irradiation

Abstract

Polyols undergo rapid selective transesterification with β‐ketoesters upon microwave irradiation in solvent‐free and catalyst‐free conditions to form monoesters.     

Polyurethanes from polyols obtained by ADMET polymerization of a castor oil‐based diene: Characterization and shape memory properties

The acyclic diene metathesis polymerization (ADMET) of 1,3‐di‐10‐undecenoxy‐2‐propanol, a castor oil based diene, is reported. 10‐Undecenol was used as renewable comonomer to end‐cap polymer chains and limit the molecular weight. The poly ols obtained in this way were reacted with 4,4′‐methylenebis(phenylisocyanate) (MDI) to yield a series of amorphous and semicrystalline polyurethane networks. The thermal stability and the thermomechanical and mechanical properties of these thermosets have been studied and showed good shape memory properties for the semicrystalline polymer. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Study of transaldolase deficiency in urine samples by capillary LC-MS/MS

Transaldolase (TAL) is a key enzyme of the pentose phosphate pathway (PPP). TAL deficiency is a newly recognized cause of liver cirrhosis. We have developed an ion-pair LC separation combined with negative ion electrospray MS/MS detection method to assess PPP metabolites in urine samples from TAL-deficient mice. Sedoheptulose 7-phosphate (S7P), C5-polyols D-arabitol and D-ribitol, and 6-phosphogluconate (6PG) levels were markedly increased in urine of TAL-deficient mice with respect to those of wild-type and heterozygote littermates. The detection limits of S7P, D-arabitol, and 6PG were 0.15 +/- 0.015 pmol, 3.5 +/- 0.41 pmol, and 0.61 +/- 0.055 pmol, respectively. The limit of quantitation was 0.4 +/- 0.024 nmol/ml for S7P, 1.6 +/- 0.11 nmol/ml for 6PG and 10 +/- 0.7 nmol/ml for D-arabitol. Additional metabolites, hexose 6-phosphates (m/z 259), D-ribose 5-phosphate and D-xylulose 5-phosphate (m/z 229), D-fructose 1,6-diphosphate (m/z 339), C6-polyols (m/z 181) and GSSG (m/z 611), that have been positively identified in mouse urine, showed similar levels in control and TAL-deficient mice.     

Ring‐opening polymerizations of propylene oxide by double metal cyanide catalysts prepared with ZnX2 (X = F,Cl, Br,or I)

Polymerizations of propylene oxide were carried out with double metal cyanide (DMC) catalysts based on Zn₃[Co(CN)₆]₂. Through the control of the type and amount of ZnX₂ (X = F, Cl, Br, or I) during the preparation of the catalyst, the catalytic activity, induction period, and unsaturation level in the polyether polyols could be tuned. The DMC catalysts were characterized by X‐ray photoelectron spectroscopy, infrared spectroscopy, and X‐ray powder diffraction. In general, ZnBr₂ was the most effective zinc halide with respect to the properties of the resulting polymers as well as the activity and induction period. The average rates of polymerizations of DMC catalysts prepared with ZnCl₂, ZnBr₂, and ZnI₂ were 889, 1667, and 784 g of polyoxypropylene/g of catalyst h, respectively, with induction periods of about 53, 5, and 60 min, respectively, at 115 °C. The DMC catalysts produced polyoxypropylenes with an ultralow unsaturation level (0.0025–0.0057 mequiv/g) and a narrow molecular weight distribution (1.07–1.42) without high‐molecular‐weight tails; this resulted in a low viscosity (962–3950 cP). According to the results collected from catalyst characterizations and polymerizations, the active sites of DMC‐catalyzed polymerization had mainly coordinative characters. The presence of free anions accelerated the ring‐opening procedure and thus enhanced the propagation rate and shortened the induction period. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 4393–4404, 2005     

Kinetic evaluation of polyol production by three-phase catalytic hydrogenation of saccharides

Kinetic evaluations were accomplished in a discontinuous three-phase reactor for saccharose, glucose and fructose hydrogenations at 373, 393 and 413 K, and 24 atm. Selectivities attained values in the order of 99.05%. Langmuir-Hinshelwood models based on heterogeneous mechanisms were proposed and the optimization and kinetic quantification of the process were performed.This revised version was published online in December 2005 with corrections to the Cover Date.     

Metal-ligand cooperation in the catalytic dehydrogenative coupling (DHC) of polyalcohols to carboxylic acid derivatives

Several polyols, which are easily available from sugars through biochemical conversion or hydrogenolytic cleavage, are directly converted into carboxylic acids and amides. This efficient dehydrogenative coupling process, catalyzed by a rhodium(I) diolefin amido complex, is an attractive approach for the production of organic fine chemicals from renewable resources. This method tolerates the presence of several hydroxy groups and can be extended to the direct synthesis of lactams from the corresponding amino alcohols under mild conditions.     

Graft‐Copolymer‐Based Approach to Clear,Durable, and Anti‐Smudge Polyurethane Coatings

Clear anti‐smudge coatings with a thickness of up to tens of micrometers have been prepared through a graft‐copolymer‐based approach from commercial precursors. The coatings repel water, diiodomethane, hexadecane, ink, and an artificial fingerprint liquid. In addition, they can be readily applied onto different substrates using different coating methods. These coatings could find applications in protecting hand‐held electronic devices from fingerprints, windows from stains, and buildings from graffiti.     

MOR负载的自还原型双功能催化剂用于催化纤维素氢解制乙二醇的研究

以丝光沸石分子筛(MOR)为载体,以高温生物碳源分解产物H2或CO为还原剂,采用等体积浸渍法制备自还原型双功能催化剂Ni-W/MOR,不经过还原过程直接将其应用于纤维素水相氢解制备低碳乙二醇的研究。考察了催化剂的煅烧温度、活性金属含量配比对纤维素转化率和目标产物收率的影响。结果表明,催化剂的煅烧温度在773 K为宜;XRD表征结果说明,催化剂中活性金属结晶度和晶体的种类与催化剂的配比有关;TEM照片可直观地说明,采用上述方法制备的催化剂中活性金属在载体上具有较好的分散性,粒径均小于20 nm。当Ni、W含量分别为10%和15%,煅烧温度为773 K,反应条件为513 K、5.0 M Pa、2 h时低碳多元醇总收率为56.92%,其中,乙二醇收率为52.30%。