Rhodia Operations

Rhodia Fiber & Resin Intermediates

Hubert Gayet

Denis Revelant

Martine Vibert

Bruno Heinisch

Philippe Leconte

Laurent Garel

Jean-Claude Le Thiesse

Jean-Claude Masson

Philippe Perrona

The invention relates to a natural vanillin, which is in the form of an amorphous solid of which the color, in ethanolic solution at 10% by weight, is less than or equal to 200 Hazen, preferably less than or equal to 100 Hazen.

Method for the purification of natural vanillin

The invention relates to a method for the purification of natural vanillin, comprising at least one step in which the natural vanillin is evaporated.

The invention relates to a method for producing at least one alkoxy-hydroxybenzaldehyde (AHBA) from at least one hydroxyphenol (HP), said method being characterized in that it comprises the formation of at least one alkoxyphenol (AP) and alkyl-alkoxyphenol (AAP) and the separation (S) of AP from AAP, said separation (S) being carried out prior to obtaining AHBA.

Method for producing alkoxy-hydroxybenzaldehyde that is substantially free of alkyl-alkoxy-hydroxybenzaldehyde

A method for separating and recovering an aromatic aldehyde from a mixture thereof that also contains tar and light and heavy impurities, includes feeding the liquid flow containing this mixture into an evaporator, vaporizing the mixture in order to separate, on the one hand, a gaseous flow containing the aromatic aldehyde, the light impurities, the heavy impurities that can be vaporized at the selected evaporation temperature and pressure and, on the other hand, a liquid flow essentially containing the tar, and recovering the aromatic aldehyde from the separated gaseous flow.

Separation of aromatic aldehydes

Separation and purification of hydroquinone from crude mixtures thereof essentially containing hydroquinone in combination with very small amounts of impurities including resorcinol and pyrogallol, include a topping distillation allowing the resorcinol to be removed as the distillation top product, and allowing a crude mixture essentially containing hydroquinone and the heavy impurities to be recovered at the column bottom, such mixture then being subjected to a bottoming distillation which allows the pyrogallol to be removed at the column bottom and allows hydroquinone in a purified form to be recovered at the column top.

Separation and purification of hydroquinone from crude mixtures thereof

Purified hydroquinone is prepared and formed from raw compounds essentially containing hydroquinone associated with very small quantities of impurities including resorcinol and pyrogallol, and includes a distillation purification step in which the resorcinol and pyrogallol are eliminated, directly followed by a step in which the purified hydroquinone is formed.

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Villeurbanne, France

Hubert Gayet