Lignin is subject to easy radiation-peroxidation. In the case of pine hydrochloric acid lignin, irradiation of 1.92 Megarads of γ-ray in air gave rise to 3×1019 peroxide per gram of lignin. When the peroxidized lignin was allowed to stand in air, the peroxide contents diminished in 25 days to 40%, which was, thereafter, invariable for 250 days. When styrene or methyl methacrylate was used as monomer in the grafting there was reaction of 36 parts of styrene or of 39 parts of methyl methacrylate to 100 parts of lignin, but it was not the case with ligninsulfonic acid. Up to 1.92 Megarads of dose amount applied, the peroxide concentration in lignin increased proportionally with the radiation period, but the grafting ratio indicated maximum value at the point of a peroxide content of 1.89×1019 per gram of lignin. When polystyrene branches propagated up to Pn of 100, the corresponding grafting ratio reached to 35 in the radiation-peroxidation method and 200 in the case of direct radiation method respectively. This means that. in the case of radiation-peroxidation method, the number of active centers for grafting is one-sixth compared with those which appeared in the direct radiation grafting. From the so far known structure of lignin and the experimental results obtained here, it is to be concluded that the peroxides produced in the lignin molecules by pre-irradiation were mostly hydroperoxide arising from C-H scission at tertiary carbon, and less in diperoxide.
High polymers are not homogeneous in that they consist of fractions with various chain lengths. It is said that there is some relation between the molecular weight distribution of adhesive polymer and adhesion. To obtain the basic information about this, we studied on the preferential adsorption about molecular weight of PVAc from benzen solution on wood and cellophane. The PVAc used in the experiment was prepared from mixture of two kinds of PVA which had different average polymerisation grade of 550 and 1750, acetylating the mixture by ordinary method into PVAc, and dialysing in methanol. The wood (40∼60 mesh red lauan powder) and cellophane foil (#300) were first swollen in water, and then replaced by means of solvent by ethanol and further by benzen, to obtain swollen adsorbents. The results of the experiment are as follows, on which discussions are made. (1) The intrinsic viscosity [η] of the supernatant PVAc solution from each sample increased initially and then decreased with duration of time in shaking, and even after the amount of PVAc adsorbed seemed to reach its equilibrium in its adsorption rate curve, the intrinsic viscosity of the remaining PVAc solution changed slowly with continued shaking. Therefore, it seems probable that the lower molecular weight fractions are adsorbed faster than the higher molecular weight fractions, but that the former are replaced by the latter upon longer periods of shaking. This initial selective adsorption of lower molecular weight fractions is thought to come from their easier diffusion in solution and deposition on solid surface, and the later replacement will be interpreted by the entropy effect. (2) From the studies of extraction and fractionation7), some different phenomena were found with respect to the preferential adsorption about molecular weight, between cellophane foil which has the geometrically simple surface and porous wood powder. In the case of cellophane, following the initial selective adsorption of lower molecular weight fractions, the adsorbed low molecular weight actions were replaced simply from their lowest parts by the high molecular weight fractions, while, in the case of porous wood powder, the initial selective adsorption of lower molecular weight fractions occurred, the migration of the adsorbed polymer into the macro pore or crack of adsorbent followed, and then the replacement of the adsorbed low molecular weight fractions by high molecular weight fractions proceeded. Furthermore, some of macro pore or crack in the adsorbent were inaccessible to larger molecule, and so the replacement merely occurred on a certain surface of wood where the higher molecular weight PVAc was also approachable.
An experiment was made by preparing milled wood lignin (Björkman lignin) from pine (Pinus densiflora Sieb. et Zucc.), beech (Fagus crenata Blume) and rice straw. The pyrolysis products of these lignin preparations were analyzed by pyrolysis gas chromatography. 0.5 to 3.0mg of the sample was inserted in the pyrolytic injector head and pyrolyzed at 500°(600°) in helium. The columns were operated at 124° or 160-180°. The following column packings were used: 30% silicone oil DC 550 on celite 545, 5% diethylene glycol succinate (DEGS) on Chromosorb W, and 5% Apiezon N on Chromosorb W. The pine milled wood lignin gave guaiacol, 4-hydroxy-3-methoxytoluene, 4-hydroxy-3-methoxyethylbenzene, 4-hydroxy-3-methoxystyrene, 4-hydroxy-3-methoxypropylbenzene, eugenol, cis-isoeugenol, trans-isoeugenol, vanillin, and acetovanillone. The beech milled wood lignin gave, in addition to those mentioned above, pyrogallol-1, 3-dimethylether, 4-hydroxy-3, 5-dimethoxytoluene, 4-hydroxy-3, 5-dimethoxyallylbenzene. At higher temperature, for example at 600°, on the pine lignin pyrogram, the peaks due to 4-hydroxy-3, 5-dimethoxytoluene and 4-hydroxy-3, 5-dimethoxyethylbenzene appeared, which suggest the presence of syringyl propane unit in the pine lignin structure. The rice straw milled wood lignin gave a remarkably large amount of 4-hydroxystyrene and 4-hydroxy-3-methoxystyrene in addition to the wood-lignin pyrolysis products. However, when pyrolyzed after alkaline hydrolysis, the yield of the characteristic products extremely decreased. This fact will support the view that these ingredients have been produced from decarboxylation of the p-coumaric acid and ferulic acid which are combined to the monocotyledonous lignin as ester.
A new natural sesquiterpenic hydrocarbon C15H26, named tentatively“Apitonene-1”, was isolated from the resin of Apitong timber, presumably Dipterocarpus gracilis, imported from the Philippines, by distillation followed by chromatography on silica gel impregnated with silver nitrate. Dehydrogenation with sulphur gave S-guaiazulene (II) showing hydroguaiazulenic skeleton of the hydrocarbon. The hydrogenation in acetic acid in the presence of Adams catalyst gave a saturated hydrocarbon C15H28 whose IR spectrum nearly coincided with that of guaiane (I). In ethanol, however, no hydrogenation occurred. The IR spectrum of the original hydrocarbon (Apitonene-I) showed the presence of isopropyl group (1381, 1364, 1172cm-1) and excluded the presence of double bond outside the ring system. The mass spectrum of the original and the dihydrocompound showed molecular weight 206 and 208 respectively and the presence of isopropyl and methyl groups. Although the position of unsaturation in the ring system remains undecided, we may estimate the gross structure of“Apitonene-1” either 4, 10-dimethyl-7-isopropyl-bicyclo [0, 3, 5]-deca-4-ene (IV) or 4, 10-dimethyl-7-isopropyl-bicyclo [0, 3, 5]-deca-10-ene (V) from the results of its NMR spectrum.