天然棕色棉纤维色素光谱学特性及其化学结构初步推断

在纯化棕色棉纤维色素的基础上，测定了天然棕色棉纤维色素的紫外-可见光谱（UV光谱）、红外光谱（IR光谱）以及分析了pH值、浓度、诊断试剂对天然棕色棉纤维色素UV光谱的影响，发现天然棕色棉纤维色素UV光谱随着pH值和浓度不同而变化，诊断试剂对纤维色素UV光谱也有影响，但并不符合黄酮类化合物对诊断试剂的反应规律，红外光谱的主要吸收波数是3554、3477、3414、3289、1638、1618、1386、1073、617、478cm^-1。结合化学性质鉴定，以及和已知的白色棉种皮色素比较。初步推断棕色棉色素的化学结构，认为棕色棉纤维中的色素是由单宁物质氧化形成的醌类化合物。最后解释了棕色棉纤维具有颜色是因为棉纤维发育后期缩合单宁接触空气后氧化的结果。

Preliminary Deductions of the Chemical Structure of the Pigment Brown in Cotton Fiber

We aimed to determine the features of ultraviolet and infrared spectra of the pigment brown in natural cotton fiber, analyze the effects of pH values and concentrations, diagnose reagents in the ultraviolet spectra, and identify the chemical properties of the pigment. We first purified the brown pigment for use in all experiments. The ultraviolet spectra varied with pH values and concentrations and was influenced by diagnosed reagents. However, the effects of diagnosed reagents were not the same as those of flavones. The infrared spectra showed the wave numbers 3 554, 3 477, 3 414, 3 289, 1 638, 1 618, 1 386, 1 073, 617, and 478 cm^-1. The chemical features and purification methods of the brown pigment were compared with those of the pigment in the seed coat of white conventional cotton, studied by Halloin in 1982, revealing similarities between the two pigments. Thus, the brown pigment in natural cotton fiber is a quinone compound from tannin oxidation at the end of fiber development.