N-Hydroxy Compounds as New Internal Standards for the 31P-NMR Determination of Lignin Hydroxy Functional Groups
N-Hydroxy Compounds as New Internal Standards for the 31P-NMR Determination of Lignin Hydroxy Functional Groups
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DOI：
10.1515/hf.2001.047
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发表时间：
2001-04
期刊：
影响因子：
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通讯作者：
M. Zawadzki;A. Ragauskas
中科院分区：
文献类型：
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作者：
M. Zawadzki;A. Ragauskas
TMDP（2-chloro-4，4，5，5-tetramethyl-1，3，2-dioxaphosphorane）是一种非常有效的标记羟基的试剂，作为31 P-NMR活性亚磷酸酯衍生物（图1）。TMDP衍生化/31 P-NMR光谱已有效地用于分析硫酸盐法制浆（Ahvazi et al. 1998; Froass et al. 1998）和各种漂白操作（Froass et al.1996; Wang et al. 1997; Sun and Argyropoulos 1996; Sun and Argyropoulos 1995）过程中木质素结构的变化。通常，选择环己醇作为TMDP/31 P-NMR方法的内标物（Granata和Argyropoulos 1995）。根据我们的经验，我们发现环己醇亚磷酸酯产物偶尔会与衍生的脂肪族和酚类木质素结构重叠（图2，也参见Zawadzki和Ragauskas 1999）。胆固醇也被用作内标物（Smit等人，1997），但不幸的是，亚磷酸酯产物的化学位移与环己醇的化学位移非常相似（表1）。显然，当研究显示分散的脂肪族和酚亚磷酸酯区域的木质素样品时，基线分辨的内标物将是有用的。已知TMDP与含有不稳定氢的各种杂原子官能团反应;例如，OH、CO2 H、NH和SH（Wroblewski等人，1988）。由于TMDP反应性的范围，我们已经研究了由各种底物产生的亚磷酸酯反应产物。在本文中，我们提出，N-羟基化合物可能是有用的新的内标物的TMDP/31 P-NMR分析分离的木质素。
TMDP (2–chloro–4,4,5,5–tetramethyl–1,3,2–dioxaphospholane) is a very powerful reagent for tagging hydroxy groups as the 31P-NMR active phosphite derivative (Fig. 1). TMDP derivatization/ 31P–NMR spectroscopy has been effectively applied to analyze lignin structural changes during kraft pulping (Ahvazi et al. 1998; Froass et al. 1998) and various bleaching operations (Froass et al.1996; Wang et al. 1997; Sun and Argyropoulos 1996; Sun and Argyropoulos 1995 ). Usually, cyclohexanol is selected as an internal standard for the TMDP/31P–NMR method (Granata and Argyropoulos 1995). In our experience, we have found that occasionally the cyclohexanol–phosphite product overlaps with derivatized aliphatic and phenolic lignin structures (Fig. 2, also see Zawadzki and Ragauskas 1999). Cholesterol has also been used as an internal standard (Smit et al. 1997), but unfortunately, the chemical shift for the phosphite product is very similar to that of cyclohexanol (Table 1). Clearly, an internal standard that is baseline resolved would be useful when investigating lignin samples displaying disperse aliphatic– and phenolic–phosphite regions. TMDP is known to react with a variety of heteroatom functional groups containing labile hydrogen; for example, OH, CO2H, NH, and SH (Wroblewski et al. 1988). Because of the range of TMDP reactivity, we have investigated the phosphite reaction products arising from a variety of substrates. In this paper, we propose that N-hydroxy compounds may be useful new internal standards for TMDP/31P–NMR analysis of isolated lignins.