Catalysts halogenation

Graves etaU US Patent 6,206,819 (March 27, 2001) Assignee Rohm and Haas Company Utility Acetyl Chlorination Catalyst 

Di-n-octylamine (0.021 mol), 37% HCl (0.062 mol), and cumene (40 g) were refluxed for 1 hour to remove water and then cooled to 120 °C. Thereafter, formamide (0.056 mol) was added and the reaction monitored by gas chromatography until completed. The mixture was cooled to ambient temperature, washed 3 times with 40 ml of water, the organic layer concentrated by vacuum distillation, and the product isolated as a yellow oil in 95% yield. 

The product from Step 1 (0.0074 mol), n-butyl ether (50 g), 2,6-trifluoromethyl-4-sec-butyl-3,5-di-carboxylic acid pyridine (0.146 mol) were heated to 95 °C and thionyl chloride (0.438 mol) added to the reaction pot over 3 hours. Both excess thionyl chloride and the reaction solvent were removed by vacuum distillation at 100 °C at 5mmHg. The product was isolated by vacuum distillation at 130 °C at l-2mmHg in 86.2% yield. 

Previously N-methylstearylamide was used as an acid halide catalyst using either thionyl chloride or phosgene (1). 

An alternative method for preparing the product of Step 1 is by the catalytic oxidation of tertiary amines using CUCI2 and either Nal or NH4I in an atmosphere of 500 psig oxygen 

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The halogen carriers or aromatic halogenation catalysts are usually all electrophilic reagents (ferric and aluminium haUdes, etc.) and their function appears to be to increase the electrophilic activity of the halogen. Thus the mechanism for the bromination of benzene in the presence of iron can be repre-sfflited by the following scheme ... 

Iodine monochloride [7790-99-0] ICl, mol wt 162.38, 78.16% I, is a black crystalline soHd or a reddish brown Hquid. SoHd ICl exists ia two crystalline modifications the a-form, as stable mby-red needles, d = 3.86 g/mL and mp 27.3°C and as metastable brownish red platelets, d = 3.66 g/mL, mp 13.9°C and bp 100°C (dec). Iodine monochloride is used as a halogenation catalyst and as an analytical reagent (Wij s solution) to determine iodine values of fats and oils (see Fats and fatty oils). ICl is prepared by direct reaction of iodine and Hquid chlorine. Aqueous solutions ate obtained by treating a suspension of iodine ia moderately strong hydrochloric acid with chlorine gas or iodic acid (118,119). 

Vaillancourt, F.H., Yeh, E., Vosburg, D.A. et al. (2006) Nature s inventory of halogenation catalysts oxidative strategies predominate. Chemical Reviews (Washington, DC, United States), 106, 3364—3378. 

F.H. Vaillancourt, E. Yeh, D.A. Vosburg, S. Garneau-Tsodika, C. Walsh, Nature s inventory of halogenation catalysts Oxidative strategies predominate, Chem. Rev. 106 (2006) 3364-3378. 

Year Natural Products Metal Halogen Catalyst Major Author Reference... 

Thus, at 372°C. and over the range of pressures and hydrogen to n-pentane ratios covered in the investigation, it appears that the proposed mechanism can account in large part for the observed kinetic data. However, Starnes and Zabor (S8) have proposed an alternative mechanism, based on their studies of n-pentane isomerization over platinum-alumina-halogen catalysts. They postulate that the paraffin is adsorbed on platinum sites with dissociation of a hydrogen atom, followed by polarization of the adsorbed species. 

Calculation of Conversion of 1-Methyl-2-Ethylcyclopentane to C Aromatic Isomers over Platinum-Alumina-Halogen Catalyst (K3) ... 

Vaillancourt EH, Yeh E, Vosburg DA, Gameau-Tsodikova S, Walsh CT (2006) Nature s Inventory of Halogenation Catalysts Oxidative Strategies Predominate. Chem Rev 106 3364... 

Use Printing and dyeing woolens, moth-proofing, halogenation catalyst. 

Haensel, V., inventor Universal Oil Products Company, assignee. "Alumina-platinum-halogen catalyst and preparation thereof." U.S. Patent 2,479,109. 7 pages. August 16, 1949. 

Bromine and iodine, because of their capacity to form mixed halogens, e.g., BrCl, BrFs, and ICl which have a low energy of activation, are excellent halogenation catalysts. In general, it can be stated that small quantities of iodine and bromine are frequently added along with other less costly chlorine carriers, and the literature records numerous examples of such halogenations. 

Incompatibilities and Reactivities Oxidizers, peroxides, halogens, catalysts for vinyl or ionic polymers aluminum, iron chloride, copper [Note Usually contains an inhibitor such as tert-butyl catechol.]... 

Somewhat less clear is the nature of catalysis by halogens and positive halogen compounds, such as I2 [176, 177], NBS [178], tetra-N-butylammonium tribromide [179], and hexamethylenetetramine-bromine complex [180]. These compounds would be expected to react with indoles by halogenations, generating the hydrogen halide as a by-product. Another halogenated catalyst, 2,4,6-trichlorotriazine, is believed to function by generation of HCl in the presence of moisture [181]. 

In most of reactions activated carbons act as halogenation catalyst or as oxidation catalyst. 

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