Hoechst Celanese Corporation

Other

Daniel D Lindley

Thomas A Curtis

Timothy R Ryan

Thomas M Kenesson

Edward M De La Garza

Olan S Fruchey

Charles B Hilton

Edward G Zey

Mark R Rubino

Thomas H Shockley

B Frank Wood

Huh-Sun Chiou

Susan W Jahoda

John R Battler

Charles R Hilton

Joe S Trevino

A method is provided for purifying crude N-acetyl-para-aminophenol (APAP) containing color bodies or their precursors, the method comprising: a) forming a solution of the crude APAP; and b) subsequently contacting the solution with substoichiometric quantifies of an acetylating agent for a sufficient period of time to convert said color bodies or their precursors to substantially non-color bodies/stable, colorless substances; said quantities of acetylating agent provided is such that substantially none of the APAP is converted to other compounds.

Color control & stability in acetaminophen

A continuous process is disclosed for the acylation or alkylation of aromatic compounds in hydrogen fluoride. The aromatic compound is sufficiently insoluble in hydrogen fluoride that a two phase reaction medium forms. However, surprisingly, the product acylated or alkylated aromatic compound is soluble in hydrogen fluoride. The present invention particularly relates to use of a continuous, multi-stage process for carrying out the acylation or alkylation reaction. In the multi-stage process, the continuous phase can be either the hydrogen-fluoride rich phase or the aromatic compound-rich phase. The movement of the continuous phase relative to the non-continuous (dispersed) phase can be countercurrent or concurrent. The multi-stage process can be operated in a manner such that the aromatic compound feed to the reaction is entirely consumed or such that unreacted aromatic compound is recycled.

Process for acylation or alkylation of aromatic compounds in hydrogen

The present inventon pertains to a process for the preparation of omega-arylalkanoic acids of the genral formula

Process for the preparation of omega-arylalkanoic acids

A continuous process is provided for the production of 4'-isobutylacetophenone (4-IBAP) comprising feeding liquid hydrogen fluoride (HF) and an acetylating agent into an extractor-reactor to form a first, HF-rich phase containing the acetylating agent, feeding isobutylbenzene (IBB) to the extractor-reactor to form a second, IBB-rich phase which is contacted with said first, HF-rich phase in a manner such that the acetylating agent reacts with IBB to form 4-IBAP which is extracted into the first, HF-rich phase, and a light IBB-rich second phase containing the bulk of unreacted IBB, externally recycling said second, IBB-rich phase to the IBB feed point in combination with fresh IBB to make up for IBB consumed in the reaction and that and dissolved in the HF-rich phase, and withdrawing HF-rich phase containing 4-IBAP from the extractor-reactor.

Process for the production of 4'-isobutylacetophenone

A method is provided for separating hydrogen fluoride (HF) from a mixture comprising HF complexed with an aromatic ketone in which the keto carbon atom is directly bonded to an aromatic ring carbon atom, e.g., 4-isobutylacetophenone, by adding a carboxylic acid anhydride, e.g., acetic anhydride, to the mixture while maintaining the mixture at conditions sufficient to sustain a reaction between the anhydride and the HF to form the corresponding acyl fluoride, e.g., acetyl fluoride, and carboxylic acid, e.g., acetic acid, and separating the acyl fluoride from the mixture. The method is conveniently carried out in a stripping column near the top of which the mixture comprising aromatic ketone and HF is fed and below which the anhydride is fed. Between these feed points, the uncomplexed HF is stripped from the mixture, while below the anhydride feed point or points, the anhydride reacts with the complexed HF to form the acyl fluoride which is stripped from the mixture, and the carboxylic acid. The separation method may be integrated with the production of the aromatic ketone by the Friedel-Crafts acylation of an aromatic compound, e.g., isobutylbenzene with an acyl fluoride, a carboxylic acid anhydride, a free carboxylic acid, or a mixture of the foregoing reactants, using an excess of HF as catalyst, to produce the mixture comprising aromatic ketone and HF to be separated, and to which the separated HF and in some cases the acyl fluoride may be recycled.

Method for removing hydrogen fluoride from mixtures comprising aromatic

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Portland, TX, United States of America

Daniel D Lindley