β-D-threo-(2-13C)-2-pentulofuranose | 132497-59-7

• 分子结构分类: 有机化合物 - 有机氧化合物
• 英文名称: β-D-threo-(2-13C)-2-pentulofuranose
• CAS: 132497-59-7
• 化学式: C₅H₁₀O₅
• 分子量: 151.12
• InChiKey: LQXVFWRQNMEDEE-MOFMDCFQSA-N

反应信息

• 作为反应物：
  描述：

  β-D-threo-(2-13C)-2-pentulofuranose 以 重水 为溶剂， 生成 α-D-threo-(2-13C)-2-pentulofuranose 、 keto-(2-13C)-D-xylulose
  参考文献：
  名称：

  Furanose ring anomerization: kinetic and thermodynamic studies of the d-2-pentuloses by 13C-n.m.r. spectroscopy

  摘要：

  The tautomeric compositions of D-erythro-2-pentulose (D-ribulose) and D-threo-2-pentulose (D-xylulose) in aqueous solution have been studied by 13C-n.m.r. spectroscopy at various temperatures using 2-13C-substituted compounds. The alpha-furanose, beta-furanose, and acyclic carbonyl (keto) forms were detected at all temperatures, whereas the acyclic hydrate (gem-diol) form was not observed. The percentage of keto form increased with increasing temperature, at the expense of the furanose forms. Thermodynamic (delta G0, delta H0, delta S0) and kinetic parameters for the interconversion of alpha- and beta-furanoses with the acyclic carbonyl form were determined and compared with those determined under similar conditions for the structurally-related aldotetrofuranoses. The ring-opening rate constant (kopen) measured by 13C saturation-transfer n.m.r. spectroscopy in 50mM sodium acetate (pH 4.0) at 55 degrees were as follows: beta-threofuranose (0.65 s-1) greater than alpha-erythrofuranose (0.51 s-1) greater than beta-erythrofuranose (0.37 s-1) approximately beta-threo-2-pentulofuranose (0.35 s-1) greater than alpha-threofuranose (0.25 s-1) greater than alpha-threo-2-pentulofuranose (0.20 s-1) approximately alpha-erythro-2-pentulofuranose (0.18 s-1) approximately beta-erythro-2-pentulofuranose (0.18 s-1). Within each structural type the pentulofuranose anomer having O-2 and O-3 cis (O-1 and O-2 cis in aldotetrofuranoses) opens faster than, or at a similar rate to, the alternative anomer having these oxygen atoms trans. Ring-closing rate constants (kclose), calculated from kopen and Keq, decrease in the order beta-erythrofuranose (15 s-1) greater than beta-threofuranose (12 s-1) greater than alpha-erythrofuranose (9.9 s-1) greater than alpha-threofuranose (6.2 s-1) greater than beta-threo-2-pentulofuranose (0.71 s-1) greater than alpha-erythro-2-pentulofuranose (0.38 s-1) greater than alpha-threo-2-pentulofuranose (0.13 s-1) approximately beta-erythro-2-pentulofuranose (0.13 s-1). Replacement of H-1 in aldotetrofuranoses by a hydroxymethyl group (i.e., conversion to 2-pentuloses) significantly decreases the ring-opening and ring-closing rate constants of furanose anomerization.

  DOI：

  10.1016/0008-6215(90)84001-b
• 作为产物：
  描述：

  α-D-threo-(2-13C)-2-pentulofuranose 以 重水 为溶剂， 生成 β-D-threo-(2-13C)-2-pentulofuranose 、 keto-(2-13C)-D-xylulose
  参考文献：
  名称：

  Furanose ring anomerization: kinetic and thermodynamic studies of the d-2-pentuloses by 13C-n.m.r. spectroscopy

  摘要：

  The tautomeric compositions of D-erythro-2-pentulose (D-ribulose) and D-threo-2-pentulose (D-xylulose) in aqueous solution have been studied by 13C-n.m.r. spectroscopy at various temperatures using 2-13C-substituted compounds. The alpha-furanose, beta-furanose, and acyclic carbonyl (keto) forms were detected at all temperatures, whereas the acyclic hydrate (gem-diol) form was not observed. The percentage of keto form increased with increasing temperature, at the expense of the furanose forms. Thermodynamic (delta G0, delta H0, delta S0) and kinetic parameters for the interconversion of alpha- and beta-furanoses with the acyclic carbonyl form were determined and compared with those determined under similar conditions for the structurally-related aldotetrofuranoses. The ring-opening rate constant (kopen) measured by 13C saturation-transfer n.m.r. spectroscopy in 50mM sodium acetate (pH 4.0) at 55 degrees were as follows: beta-threofuranose (0.65 s-1) greater than alpha-erythrofuranose (0.51 s-1) greater than beta-erythrofuranose (0.37 s-1) approximately beta-threo-2-pentulofuranose (0.35 s-1) greater than alpha-threofuranose (0.25 s-1) greater than alpha-threo-2-pentulofuranose (0.20 s-1) approximately alpha-erythro-2-pentulofuranose (0.18 s-1) approximately beta-erythro-2-pentulofuranose (0.18 s-1). Within each structural type the pentulofuranose anomer having O-2 and O-3 cis (O-1 and O-2 cis in aldotetrofuranoses) opens faster than, or at a similar rate to, the alternative anomer having these oxygen atoms trans. Ring-closing rate constants (kclose), calculated from kopen and Keq, decrease in the order beta-erythrofuranose (15 s-1) greater than beta-threofuranose (12 s-1) greater than alpha-erythrofuranose (9.9 s-1) greater than alpha-threofuranose (6.2 s-1) greater than beta-threo-2-pentulofuranose (0.71 s-1) greater than alpha-erythro-2-pentulofuranose (0.38 s-1) greater than alpha-threo-2-pentulofuranose (0.13 s-1) approximately beta-erythro-2-pentulofuranose (0.13 s-1). Replacement of H-1 in aldotetrofuranoses by a hydroxymethyl group (i.e., conversion to 2-pentuloses) significantly decreases the ring-opening and ring-closing rate constants of furanose anomerization.

  DOI：

  10.1016/0008-6215(90)84001-b

文献信息

• Xylose Isomerization with Zeolites in a Two-Step Alcohol-Water Process
  作者：Marta Paniagua、Shunmugavel Saravanamurugan、Mayra Melian-Rodriguez、Juan A. Melero、Anders Riisager

  DOI：10.1002/cssc.201402965

  日期：2015.3

  reaction pathway. The most active catalyst examined was zeolite Y, which proved more active than zeolite beta, ZSM‐5, and mordenite. The yield of xylulose obtained over H‐USY (Si/Al=6) after 1 h of reaction at 100 °C was 39 %. After water hydrolysis in the second reaction step, the yield increased to 47 %. Results obtained from pyridine adsorption studies confirm that H‐USY (6) is a catalyst that combines

  大孔沸石在两步甲醇-水工艺中有效地催化了木糖向木酮糖的异构化，从而显着提高了产品收率。反应途径涉及木糖异构化为木酮糖，其部分随后与甲醇反应形成甲基木酮糖苷（步骤1），然后在加水后水解以形成其他木酮糖（步骤2）。使用13进行的NMR光谱研究C标记的木糖证实了建议的反应途径。所考察的最具活性的催化剂是Y沸石，它被证明比β，ZSM-5和丝光沸石更具活性。在100°C下反应1小时后，在H-USY（Si / Al = 6）上获得的木酮糖收率为39％。在第二反应步骤中水水解之后，产率增加至47％。从吡啶吸附研究中获得的结果证实，H-USY（6）是一种结合了Brønsted和Lewis酸位的催化剂，并且可以在乙醇介质中将木糖异构化，从而在低温下形成木酮糖。所应用的沸石可商购获得。不含任何辅助四价金属，例如锡，钛或锆；有效地异构化木糖；容易再生；并且容易回收。