Yves Le Bigot

Formic acid pulping of rice straw

Abstract Rice straw pulping with formic acid was studied for different temperatures, cooking times and acid concentrations. Delignification percentage of approximately 85% with a pulp yield of 44.4% was obtained under relatively mild cooking conditions (temperature, 100°C; cooking time, 60 min; formic acid concentration, 90%). Pulp chemical and mechanical properties were comparable with those found for pulp obtained in basic environments. However, the advantage of this technique compared with cooking in basic environments is that most of the silicon derivatives remain in the pulp.

A new procedure for the destructuring of vegetable matter at atmospheric pressure by a catalyst/solvent system of formic acid/acetic acid.Applied to the pulping of triticale straw

Abstract The selective separation of cellulose, hemicelluloses and lignin of triticale straw is achieved, at atmospheric pressure, using a mixture of formic acid/acetic acid/water. The chemical and mechanical characteristics of the obtained pulp are good. The majority of the silica derivatives are retained in the pulp because of the acidic cooking conditions. The cooking agents are easily recyclable without combustion of the cooking liquor. The lignin and sugars are also isolated. This method of cooking the vegetable matter provides paper pulp which is very well suited to a TCF bleaching sequence. Use of this sequence produces bleached pulps of very satisfactory chemical and optical characteristics.

A preliminary study on polyhydrazides incorporating furan moieties

Solution and interfacial polycondensation of difuranic dihydrazides with aromatic or aliphatic dicarboxylic acid dichlorides led to the corresponding polyhydrazides which were characterized in terms of structure and average chain length. Their conversion to the corresponding polyoxadiazoles was also examined. Model compounds were prepared to facilitate the synthesis and the characterization of the polymers.

Synthesis of New bis-Iminocoumarins by Schmidt Reaction Catalyzed by Ion-Exchange Resins

Abstract A new synthetic route to bis-iminocoumarins is proposed which involves the synthesis of iminocoumarins from reaction of 2-hydroxybenzaldehydes with arylacetonitriles and their coupling with aromatic diamines. Ion-exchange resins were used as catalysts in both steps of this synthesis. The reaction parameters were varied and obtained using Amberlyst 15 resin in cyclohexane at 80°C.

Reaction de wittig en milieu heterogene solide-liquide : transformation directe des aldehydes phenoliques naturels en alcenes

Abstract New alkenylphenols can be obtained directly, without protecting the phenol group from the condensation reaction between phenolic aldehydes and various phosphonium salts in the presence of potassium carbonate in protic and aprotic media, using a solid-liquid phase transfer.

Synthesis of New Iminocoumarins Bearing Parabanic Moieties

Abstract The synthesis of novel substituted 3-p-nitro-phenyliminocoumarins and corresponding N-ureaiminocoumarins is described. The condensation of these materials with oxalyl chloride leads to the corresponding N-parabanic iminocoumarins, which have not previously been described, in moderate or good yields and high selectivity. The structures were characterized by Fourier transform infrared, 1H and 13C NMR, and elemental analysis.

Biomass as a source of chemicals. III — synthesis of new tetrasubstituted 1, 3-dioxacyclohexanes

Abstract New 1,3-dioxacyclohexane derivatives were obtained from aldehydes originating from biomass. The two reaction steps involved the Wittig reaction, using a solid-liquid phase transfer process, and the Prins reaction in the presence of ion-exchange resins as catalysts.

Electron ionization mass spectrometry of difurfuryl diamines

Electron impact mass spectrometry (ei-ms) has aided the structural characterization of a novel series of synthetic difuranic diamines and permitted the comparison with a previous study employing electrospray ionization mass spectrometry. As expected, the molecular radical ion was inexistant in this series of compounds and the fragmentation routes of the molecular radical ion were governed either by homolytic cleavage of the radical R2• or by heterolytic loss of NH3 to give their respective base peaks.