Michel Delmas

Ethanolysis of rapeseed oil: Quantitation of ethyl esters, mono-, di-, and triglycerides and glycerol by high-performance size-exclusion chromatography

High-performance size-exclusion chromatography (HPSEC) was used to evaluate the influence of different variables affecting the transesterification of rapeseed oil (RSO) with anhydrous ethanol and sodium ethoxide as catalyst. The effect of temperature, ethanol/RSO molar ratio, catalyst concentration, and time can be interpreted by observing the variations of the reaction medium composition. HPSEC has made the quantitation of ethyl esters, mono-, di-, and triglycerides and glycerol possible. The best results for laboratory-scale reactions were obtained at 80°C with a 6:1 molar ratio of EtOH/RSO and 1% of NaOEt by weight of RSO.

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.

Dimethyl sulphide: the secret for black truffle hunting by animals?

The capacity of animals to detect underground black truffles ( Tuber melanosporum ) was studied by burying samples of 5α-androstenol, reported as a truffle pheromone, of Nature — Identical Black Truffle flavouring, and of solutions of the different volatile components previously identified in black truffles. Both trained truffle dogs and pigs detected exclusively the flavouring samples and the solutions of dimethyl sulphide which appeared to be responsible for the animals localization of black truffles.

Synthesis of Thiiranes from Epoxides in the Presence of Thiourea in a Weakly Hydrated Organic Medium

Abstract Reactivity of thiourea in the absence or in the presence of ethanol, towards several furanic, aromatic, aliphatic, and cyclic epoxides is studied. These results are compared to other ones obtained in the same conditions with another sulfured agent: KSCN.

New Synthesis of Substituted Difuryl or Dithienyl Methanes

Abstract New trisubstituted methanes derivatives are quantitatively and selectively obtained by condensation of 2-methylfuran or 2-methylthiophene with diverse aldehydes using macroporous ion-exchange resins as catalyst. Hydration rate of organic phase and sulfonic sites of catalyst determines a proper reaction progress.

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 Simplified Wittig Synthesis Using Solid/Liquid Transfer Processes: II - The Use Of K2CC3 for the synthesis of alkenes from aromatic and aliphatic aldehydes

Abstract Theinterest of solid-liquid transfer processes in the wittig reaction in the presence of solid sodium hydroxide shown recently (1).

Determination of peroxides and hydroperoxides with 2,2-diphenyl-1-picrylhydrazyl (DPPH). Application to ozonized ethylene vinyl acetate copolymers (EVA)

Abstract The compound 2,2-diphenyl-1-picrylhydrazyl (DPPH) is a stable free radical often used to determine the quantity and the decomposition rate constant of macroinitiators such as ozonized polymers. In fact, DPPH induces the decomposition of hydroperoxides and has no effect on the decomposition of peroxides. Consequently, the hydroperoxides are the only species determined by the method described in the literature. Consequently, the decomposition rate of ozonized polymers measured with this method is wrong. It may be an explanation due to the low activation energy and rapid decomposition rate always found by this method of assay. Using the selective deactivation of hydroperoxides we show that the hydroperoxides are the more numerous initiators in an ethylene vinyl acetate copolymer. They can initiate the polymerization of vinyl monomers. On the other hand, peroxides are in a minority and their decomposition simply carries away a slight degradation by chain scissions.

Oil and paper pulp from Cynara cardunculus: preliminary results

Abstract Cynara cardunculus , the primitive wild form of the artichoke, was used only as a forage. The analysis of the seeds and the stalks of this plant showed that both these parts could be used; the seeds for vegetable oil production and the stalks for paper pulp manufacturing. The first results showed that oil extracted from Cynara seeds has a similar composition as sunflower oil and the paper pulp obtained by chemical pulping of the stalks is of good quality.

Oxidation of rapeseed oil: Effect of metal traces

Traces of heavy metals in edible oils are known to have an effect on the rate of oil oxidation. In this investigation we studied the effect of trace metals by excluding instead of adding them. Three supports were used to fix trace metals: grafted cellulose, cationic resin and absorbent resin. Cationic resin and grafted cellulose allowed copper (Cu) and iron (Fe) to be fixed. The measurement of peroxide value and variation of linolenic acid with temperature indicate good oxidative stability of oil processed on cellulose and cationic resin. These results confirm the effect of metals, particularly Fe and Cu, on oil oxidation.