Reductive cleavage by sodium in liquid ammonia of the lignin of cotton-plant stems

Summary 1. The reductive degradation by metallic sodium and liquid ammonia of the lignin of green cotton-plant stems has confirmed the presence in them of three types of structural units: syringyl, guaiacyl, and p-hydroxycoumaryl.2. The preliminary sonication of the plant with ultrasound leads to a decrease in the amount of products containing methoxy groups in the aromatic nucleus, particularly syringyl structures.Institute of the Chemistry of Plant Substances, Academy of Sciences of the Uzbek SSR, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 643–646, September–October, 1976.     

Reductive cleavage by metallic sodium in liquid ammonia of cotton lignin

Twofold cleavage with sodium in liquid ammonia of the dioxane lignin and fourfold cleavage of the native lignin from cotton stems have shown that the uncleaved parts of lignin have molecular masses 2–4 times lower than the initial lignins and consist of 15–17 phenylpropane structural units.Institute of the Chemistry of Plant Substances, Uzbek SSR Academy of Sciences, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 412–416, May–June, 1989.     

Cleavage of the natural lignin of cotton-plant stems with thioacetic acid in the presence of anthraquinone

The influence of additions of catalytic amounts of anthraquinone on the stages of hydrolysis in the cleavage of natural lignin by thioacetic acid has been investigated. The degree of delignification does not change under these conditions, but the yield of low-molecular-weight cleavage products increases, which indicates a profound degradation of the lignin macromolecule. The qualitative and quantitative compositions of the monomeric fractions of cleavage products do not undergo appreciable changes in the presence of anthraquinone.Institute of the Chemistry of Plant Substances, Academy of Sciences of the Uzbek SSR, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 99–101, January–February, 1986.     

The structure of the xylan from cotton-plant stems

Summary The results of a study of the products of the hydrolysis and oxidative cleavage according to Barry of cotton-plant-stem xylan has shown that its main chain consists of 14--L-anhydroxylopyranose units. Each elementary link of the xylan contains 6–7 xylopyranose units and has two side chains formed by residues of D-glucose and D-glucuronic acid, which are attached in position 2 or 3 of the xylose units of the main chain.V. I. Lenin Tashkent State University. Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 305–308, May–June, 1973.     

Investigation of phenols prepared from aspen lignin by its decomposition with a solution of sodium in liquid ammonia

Summary The decomposition of aspen lignin with sodium in liquid ammonia gave a mixture of phenols, of which dihydroeugenol, 1-(4-hydroxy-3-methoxyphenyl)-1- and -3-propanols, and 1-(4-hydroxy-3,5-dimethoxyphenyl)propane were identified by paper chromatography.