Quantitative1H and13C NMR spectroscopies of cottonplant dioxane lignin

A comparative analysis has been made of the dioxane lignins of the stems, seedling shoots, and seed coats of the cotton plant. The ratio of p-hydroxyaromatic, guaiacyl, and syringyl units in the macromolecules of the lignins has been determined, and so have the amounts of functional groups and bonds. It has been established that the main difference between the dioxane lignins from seedling shoots and seed coats of the cotton plant, on the one hand, and the lignin from the woody stems, on the other hand is a lower content of syringyl and guaiacyl units in the former.Translated from Khimiya Prirodnykh Soedinenii, No. 6, pp. 798–808, November–December, 1994.     

Investigation of the dioxane lignin of the cotton plant

Summary 1. The dioxane lignins of the stems of cotton plants in the early vegetation period, DLA-I, and in the flowering period, DLA-II, have been investigated. Their developed semiempirical formulas have been established by elementary and functional-group analyses.2. The amounts of catechol structural units in cotton-plant dioxane lignins have been determined for the first time.3. The molecular-weight distribution of the dioxane lignins has been studied and it has been shown that they have high molecular weights (22,000–23,500).Institute of the Chemistry of Plant Substances, Academy of Sciences of the Uzbek SSR, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 80–83, January–February, 1976.     

Study of the lignin of a cotton plant of the variety S-6524

The dioxane lignin (DLA) has been isolated from ripe stems of a cotton plant of the variety S-6524, and its empirical formula and molecular mass have been determined. This DLA differed from the DLA of a cotton plant of variety 108-F by a lower degree of hydroxylation and a higher degree of substitution of the aromatic rings.Institute of the Chemistry of Plant Substances, Academy of Sciences of the Republic of Uzbekistan, Tashkent, FAX (3712) 62 73 48. Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 430–431, May–June, 1994.     

A study of the lignin of the sea island cotton plant of variety S-6030

The dioxane lignin has been isolated by Pepper's method with a yield of 9.5% on the Komarov lignin from the ripe stems of the sea island cotton plant of variety S-6030. The developed emperical formula has been calculated, the IR and UV spectra have been taken, and the molecular-mass distribution has been studied. The dioxane lignin is polydisperse. M_w=10,100, M_n=5350.Institute of the Chemistry of Plant Substances, Academy of Sciences of the Uzbek SSR, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 628–630, September–October, 1983.     

Dioxane lignin from shoots of the cotton plant of variety 108-F. I

The dioxane lignin has been isolated by Pepper's method from two-week shoots of the cotton plant of variety 108-F and has been separated into two fractions — insoluble and soluble in ether — DLA-A and DLA-B, respectively. It has been shown that in the early stage of development of the cotton plant a low-molecular-weight lignin with a low degree of methoxylation and distinctly different from the lignin from ripe stems of the same cotton plant is synthesized.Institute of the Chemistry of Plant Substances, Academy of Sciences of the Uzbek SSR, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 96–98, January–February, 1984.     

The lignin of the sea island cotton plant of variety S-6030 affected by fusarial wilt. I

A comparative study of the dioxane lignins isolated from healthy and wilt-affected cotton plant stems has shown thatFusarium fungi demethylate lignin and make it more oxidized than the lignin from healthy stems.Institute of the Chemistry of Plant Substances, Academy of Sciences of the Uzbek SSR, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 6, pp. 825–827, November–December, 1985.     

An investigation of the dioxane lignin of cotton bolls

Summary 1. Dioxane lignin has been isolated from mature stems of the cotton plantGossypium hirsutum by mild acidolysis in an atmosphere of nitrogen.2. Its expanded semiempirical formula has been established by elementary and functional analyses.3. The molecular-weight distribution of the dioxane lignin has shown that it consists of high-molecular-weight and low-molecular-weight fractions.Institute of the Chemistry of Plant Substances, Academy of Sciences of the Uzbek SSR. Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 645–648, September–October, 1974.     

A study of the structure of lignins of healthy and wilt-affected cotton plants of the variety Tashkent-1

Continuing a study of the dioxiane lignins of healthy and wilt-affected cotton plants of variety Tashkent-1 (DLCT) according to vegetation period, we have performed nitrobenzene oxidation and cleavage with sodium in liquid ammonia of the natural and isolated dioxane lignins. It has been established that in the wilt-affected samples of cotton-plant stems the amount of guaiacyl and syringyl structural units increases.Institute of the Chemistry of Plant Substances, Academy of Sciences of the Uzbek SSR, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 392–396, May–June, 1979.     

Lignin of the fine-fibered cotton plant of variety S-6030 affected by fusarial wilt. II

A comparative study of the products of cleavage by sodium in liquid ammonia of the dioxane lignins (DLAs) from healthy and fusarial-wilt-affected stems of the fine-fibered cotton plant of variety S-6030 and a study of the PMR spectra of both lignins has shown that the DLA from the healthy stems is more highly condensed than the DLA of the stems affected by wilt. The main structures of DNA wilt are of the guaiacyl type. In the DLA from the affected stems, the amount of p-coumaryl structures had increased, which confirms the demethylating action of fusarial wilt on cotton-plant lignin.Institute of the Chemistry of Plant Substances, Academy of Sciences of the Uzbek SSR, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 364–366, May–June, 1986.     

Influence of additions of anthraquinone on the alkaline hydrolysis of cotton-plant lignin

The action of catalytic amounts of anthraquinone on the alkaline hydrolysis of the stems and dioxane lignin of the cotton plant of the ssp.mexicanium has been investigated. It has been established that this leads to a substantial increase in the yield of low-molecular-weight hydrolysis products. Analysis of the monomeric fractions of the hydrolysis products by the GLC method has shown the presence in them of large amounts of substances with a p-coumaryl structure. This, and also the low level of syringyl derivatives, may be caused by the demethoxylation of the lignin under the conditions described.Institute of the Chemistry of Plant Substances, Academy of Sciences of the USSR, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 391–395, May–June, 1985.     

An investigation of the lignins of healthy and wilt-affected cotton plants of variety Tashkent-1 according to the vegetation periods

Summary 1. The dioxane lignins of healthy and wilt-affected cotton plants of variety Tashkent-1 have been isolated and have been studied comparatively in relation to the vegetation period. On the basis of elementary and functional analysis, semiempirical formulas of the dioxane lignins isolated (DLCT-I to -VII) have been determined and it has been established that the dioxane lignins isolated from the wilt-affected plants contain more OCH₃ groups per phenyl-propane structural unit than the lignins of healthy plants.2. The molecular-weight distributions of the dioxane lignins have been studied and it has been shown that all the dioxane lignins isolated are polydisperse, those of the affected plants to a greater degree.Institute of the Chemistry of Plant Substances, Academy of Sciences of the Uzbek SSR, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 260–264, March–April, 1978.     

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.     

A study of the lignin of the cotton plant of the subspeciesmexicanium

p-Hydroxybenzoic, vanillic, ferulic, and syringic acids, and also p-hydroxybenzalde-hyde and vanillin, have been found in an ethanol-benzene extract of the stems of cotton plants of the subspeciesmexicanium. The dioxane lignin (DLA) has been isolated by Pepper's method, the semiempirical formula of its phenylpropane structural unit and its molecular-mass distribution have been established, and its UV, IR, and PMR spectra have been recorded. The DLA has a comparatively low molecular mass and a lower degree of polydispersity than the dioxane lignin of the cotton plant of variety Tashkent-1, while the amounts of functional groups in them coincide, with the exception of a lower amount of carboxy groups in the DLA.     

A study of the dioxane lignin of the stems of the cotton plant of variety S-4880

The dioxane lignin (DLA) has been isolated from the ripe stems of a cotton plant of the variety S-4880 B by a modification of Pepper's method. The yield was 16.9% on the Komarov lignin. The semiempirical formula of a phenylpropane structural unit has been calculated on the basis of elementary and functional analyses. It has been established that the amount of the main functional groups in the DLA and in the lignins isolated from the varieties of 108-F and Tashkent-2 basically coincide, but the DLA investigated was appreciably more highly methoxylated. The IR, UV, and PMR spectra of the DLA have been taken. The molecular-weight distribution of the DLA has been investigated and it has been shown that is is poly-disperse and has a weight-average molecular weight of 7400. Nitrobenzene oxidation and cleavage with sodium and liquid ammonia of the isolated DLA has shown that guaiacyl structural units predominate in it.Institute of the Chemistry of Plant Substances, Academy of Sciences of the Uzbek SSR, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 430–434, May–June, 1987.     

Quantitative1H and13C NMR spectroscopies of cottonplant dioxane lignin

A comparative analysis has been made of the dioxane lignins of the stems, seedling shoots, and seed coats of the cotton plant. The ratio of p-hydroxyaromatic, guaiacyl, and syringyl units in the macromolecules of the lignins has been determined, and so have the amounts of functional groups and bonds. It has been established that the main difference between the dioxane lignins from seedling shoots and seed coats of the cotton plant, on the one hand, and the lignin from the woody stems, on the other hand is a lower content of syringyl and guaiacyl units in the former.     

Cleavage by sodium in liquid ammonia of kenaf lignins and the biological activity of the cleavage products

The natural lignin of kenaf stems and fractions of the dioxane lignin of kenaf stems isolated previously were cleaved by sodium in liquid ammonia in order to study their structure. It was established that the kenaf lignins consist of three types of structural units: p-coumaryl, guaiacyl, and syringyl, with a predominance of the guaiacyl types. An antioxidation activity of the monomeric products of the degradation of the kenaf lignins has been found.Institute of the Chemistry of Plant Substances of the Uzbek SSR Academy of Sciences, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 738–742, September–October, 1987.     

Cleavage of dioxane lignin of the cotton plant with thioacetic acid

Summary 1. It has been established that the dioxane lignin of mature cotton-plant stems is cleaved by thioacetic acid. About 3/4 of the bonds in the lignin are alkyl-aryl ether bonds and only 1/4 are C-C bonds.Institute of the Chemistry of Plant Substances, Academy of Sciences of the Uzbek SSR, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 4, pp. 505–507, July–August, 1978.     

A study of the dioxane lignins of Althaea nudiflora and A. rosea

Summary 1. The lignin has been isolated from the stems of the cotton plant of a late period of vegetation by the hydrochloric acid method. The elementary composition and functional groups have been determined. The mean composition for a C₆-C₃ structural unit has been determined.2. By the oxidation of a powder of the stems of the cotton plant with nitrobenzene in the presence of alkali it has been established that the hydrochloric acid lignin is more condensed than the DLA.Institute of the Chemistry of Plant Substances, Academy of Sciences of the Uzbek SSR. Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 648–650, September–October, 1975.     

Study of the lignin of a cotton plant of the variety S-6524

The dioxane lignin (DLA) has been isolated from ripe stems of a cotton plant of the variety S-6524, and its empirical formula and molecular mass have been determined. This DLA differed from the DLA of a cotton plant of variety 108-F by a lower degree of hydroxylation and a higher degree of substitution of the aromatic rings. Institute of the Chemistry of Plant Substances, Academy of Sciences of the Republic of Uzbekistan, Tashkent, FAX (3712) 62 73 48. Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 430–431, May–June, 1994.     

Investigation of the dihydroxylignin ofAlthaea rhyticarpa

Summary 1. The developed semiempirical formula for the dioxane lignin from the stems ofAlthaea rhyticarpa has been found from the results of elementary and functional analyses.2. It has been shown that the lignin consists of high- and low-molecular-weight fractions.3. It has been shown by the nitrobenzene oxidation method that p-coumaryl, guaiacyl, and syringyl structural units are present in the lignin.Institute of the Chemistry of Plant Substances, Academy of Sciences of the Uzbek SSR, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 242–246, March–April, 1976.