Carboxymethyl potato starch was synthesized using ethanol as solvent by single and multi - step processes, and the products were analyzed with infra -red spectra, X-ray diffractogram, thermogravimetric analysis, scanning electronic microscopy, 13C -NMR and UV scanner. Results; DS of 0.75 and RE of 75% is the record of the single - step process, while DS of 1.06 and RE of 35.3% is that of the multi - step process. The microstruc-ture of the starch produced dramatically varies after the carboxymethylation; the crystallization degree decreases greatly and thermal stability increases. The substituent occurs mainly at C - 2 and C - 6 while the substituent of C - 3 is neglectable. The transmission of visible light of the carboxymethyl starch solution is much better than the original potato starch.%以乙醇为溶剂通过单步反应和多步反应制备了羧甲基马铃薯淀粉,并采用红外光谱、X-衍射、热重分析、扫描电镜、~(13)C核磁共振、紫外扫描对产品进行了分析.单步反应时取代度可以达到0.75,反应效率75%,多步反应时取代度可以达到1.06,反应效率35.3%.分析显示:淀粉微观结构发生了显著变化,结晶度大幅下降,热稳定性上升,取代位点主要分布在C-2、C-6位点上,C-3位点取代度很小,产品溶液在可见光区的透光性相对于原淀粉有极大提高.
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