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020302087

银虫 (小有名气)

[求助] 请教纤维素产物红外图谱

蓝色为纯微晶纤维素的红外
红色的纯微晶纤维素热解后的提纯产物,类似于左旋葡聚糖,但具体成分不祥,
现在想用红外看看他的结构,但多红外不懂,想请知道的同学帮忙看看红色谱图中800~1720之间的峰代表什么 ?

附件我文章的说明:The chemical structure of pyrolytic cellulose and cellulose was analyzed using FTIR. The infrared spectra are presented in Fig. 4. They were both characterized with dominant O-H stretching (3200-3500 cm-1) and C-H stretching (2850-3000 cm-1) corresponding to the aliphatic moieties. For cellulose, the O-H bending vibration frequencies at 1640 cm-1 demonstrated that the sample combined micro amount of water. The strong absorption peak at 1059 cm-1 should be the stretching vibration of C-O bond in cellulose, as well as the C-O bond in hemiacetal of pyranose [16, 17]. Compared with cellulose, the peaks at 2921 cm-1 and 2852 cm-1 indicated that there were paraffin waxes or its derivatives in the pyrolytic celluclose. The peaks at 1704 and 1621 cm-1 were C=O and C=C stretching, respectively, which resulted from the removal of water from cellulose by pyrolysis. It agreed well with the Py-GC/MS results which contained a large amount of paraffin waxes, ketones, carboxylic acids, and alkenes. C=C-H bending vibration in plane was at 800 cm-1. The stretching vibrations of C-O bond (1059 cm-1) and the typical values of β-D-glucoside (897 cm-1) were weaken.

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[ Last edited by 020302087 on 2012-3-19 at 13:16 ]
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celan

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从事NMR和有机结构鉴定40余年


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020302087: 金币+2, ★★★很有帮助 2012-03-20 14:33:08
The peaks at 1704 and 1621 cm-1 were C=O and C=C stretching, respectively。
这个判断可能是来自IR的基本知识,说服力不强。尤其是1704cm-1,这个强峰不给出可靠的解释的话,用IR表征热裂解成分是可以得到一些结构信息,但信息很有限。
建议测定GC-MS和NMR。
3楼2012-03-20 10:25:00
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