多元醇: 新一代的能源平台？

 在基于生物质的新能源战略中,多元醇正在成为新一代的能源平台. 从纤维素出发,通过热裂解、催化裂化和酸水解加氢等反应能制得多元醇,再以多元醇为原料在较温和的条件下通过水汽重整和费托合成等方法合成燃料、化学品和氢气. 本文综述了多元醇经水汽重整制燃料油和化学品或经光解制氢气的进展,介绍了纤维素类生物质资源经催化氢化和水解加氢制多元醇的研究进展. 虽然简单地套用现有的工业技术就可以转化纤维素,但这些方法在效率、能耗、规模和环保等方面还存在诸多问题,有效提高纤维素利用率的新思路仍在期待之中. 虽然采用精心设计的工艺路线可以有效地转化多元醇,但离“简约、节能、方便可行和环境友好”的要求仍有一定的差距,“一步法”或“一锅法”在未来可能是催化学家仍需持续努力的方向.     

Titration calorimetric determination of the pairwise interaction parameters of glycerol,D-threitol,mannitol, and D-glucitol in dilute aqueous solutions

Enthalpic pairwise interaction parameters, h_jj, were determined by titration calorimetry at 25°C for dilute solutions of glycerol, D-threitol, manitol, and D-glucitol in water. The parameters for these and other polyols conform to the expression h_jj (J-kg^–1)=145+135n_OH–21.5n _OH ² –41.7 _dl ² -160.5n_dlld, where n_OH=n_C is the number of hydroxyl groups (carbon atoms), n_dl is the number of dl configuration of a vicinal pair of OH-groups, and n_dlld is the number of such configurations in the polyol molecules. A rationalization of this expression is given.     

~1H-NMR测定聚醚多元醇分子量——共聚醚和混聚醚分子量测定

本文研究了用~1H-NMR测定共聚醚和混聚醚数均分子量的方法.根据测得的与酯氢峰面积对聚合段相应峰面积积分比率计算分子量,测得数据与端基化学法测量分子量对照,所获结果令人满意.     

Didecarboxylative Iron‐Catalyzed Bidirectional Aldolization towards Diversity‐Oriented Ketodiol Synthesis

1,3‐Acetonedicarboxylic acid was selectively activated by Fe(acac)₃, providing a synthetic platform for rapid synthesis of keto‐3,3′‐diols. The bidirectional aldol reaction was efficient for challenging aliphatic aldehydes, providing a rapid route to potentially bioactive complex structures.     

Unexpected Fluorescence of Polyols and PEGylated Nanoparticles Derived from Carbon Dot Formation

Synthesis of nanoparticles in high‐boiling alcohols (so‐called polyol synthesis) and surface functionalization of nanoparticles with polyethylene glycol (so‐called PEGylation) in combination with certain heating are often accompanied with an intense fluorescence in the blue to green spectral range. Based on the polyol synthesis of Zn₃(PO₄)₂ nanoparticles and a critical consideration of the relevant experimental conditions—including the presence of nanoparticles, the role of dissolved metal salts (ZnCl₂, MgCl₂, KCl), the type of the polyol (DEG, GLY, PEG400), the temperature and time of heating (150–230 °C, 1–6 h)—we can correlate the observed fluorescence to the formation of carbon dots (C‐dots) stemming from thermal decomposition (i.e., dehydration and carbonization) of the polyol. Thus, the thermal decomposition of polyols results in C‐dots with a diameter of 3–5 nm at narrow size distribution. The formation of C‐dots is confirmed by transmission electron microscopy (TEM), high‐resolution TEM (HRTEM), X‐ray powder diffraction (XRD), Fourier‐transform infrared spectroscopy (FT‐IR), and fluorescence spectra.     

1,3-Polyol arrays via the stereoselective rearrangement of vinyl acetals

A series of 1,3-dioxanyl vinyl acetals were readily synthesized from the corresponding dioxanone by a reduction and in situ acylation followed by Petasis olefination. Treatment of these vinyl acetals with BF₃·OEt₂ results in an O to C rearrangement to form anti-3,5-dihydroxyketones while a mixture of Me₃Al and BF₃·OEt₂ provides the corresponding syn relationship via a stereoretentive rearrangement.     

Solute-solute-solvent interactions in dilute aqueous solutions. Microcalorimetric study of isomeric butanediols

The heats of dilution of butane-1,2-diol, butane-1,3-diol, and butane-1,4-diol and of their mixtures were determined at 25°C. The virial enthalpic coefficients of the excess enthalpies of the binary and ternary solutions were evaluated and compared with the literature data for isomeric mono- and polyols. The enthalpic pair interaction coefficients of isomeric diols are positive. The highest value is observed for butane-1,2-diol thus supporting the importance of steric and nearest neighbors effects in the hydration properties of isomeric compounds. Mixed enthalpic coefficients were also determined and discussed.     

Preparation of macrodiols and polyols by chopping high‐molecular‐weight aliphatic polycarbonates

High‐molecular‐weight poly(1,4‐butylene carbonate) (PBC) (M_n: 40,000?90,000) was prepared through the condensation polymerization of dimethyl carbonate (DMC) and 1,4‐butanediol (BD) in the presence of 0.05 mol % sodium alkoxide catalyst. The subsequent feeding of 15 mol % HOAOH, such as 1,6‐hexanediol, 1,5‐pentanediol, 1,4‐cyclohexanedimethanol, or 1,4‐benzenedimethanol and stirring at 190–150 °C converted the extremely thick high‐molecular‐weight polymer to low‐molecular‐weight macrodiols with GPC‐measured M_n ～2000. The analysis of the ¹H NMR spectra indicated that the –A– units and 1,4‐butylene units were randomly distributed in the resulting oligomers. The chopping of the high‐molecular‐weight PBC using either triols or tetraols such as glycerol propoxylate, 1,1,1‐tris(hydroxymethyl)ethane, or pentaerythritol also afforded macropolyols containing branched chains with GPC‐measured M_n ～2000. When the chopped polymers were genuine PBCs, the resulting macrodiols or polyols were in a waxy state at room temperature. However, permanently oily compounds were obtained when the chopped polymers were prepared using 0.90 mole fraction of BD admixed with various other diols. The macrodiols and polyols synthesized in this study may have potential applications in the polyurethane industry. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 1570–1580