Preparation of.alpha.-Halocarbonyl Compounds , Hive Chemistry Discourse


		lutesium (Newbee) 08-26-04 11:03 No 527532				Preparation of.alpha.-Halocarbonyl Compounds
						http://nr.stic.gov.tw/ejournal/ChiChemSociety/1997/EJ52-1997-309.tif A Convenient Halogenation Procedure for the Preparation of.alpha.-Halocarbonyl Compounds Cheng, Sheng-Fan ; Lin, Ching-Shan ; Liu, Lilian Kao Abstract. Except for substituted acetophenones (p-Y-C/sub 6/ H/sub 4/COCH/sub 3/, Y=H, Br, CH/sub 3/O), simple ketones,.beta.-ketoesters and 1,3-diketones reacted smoothly with a preformed homogeneous mixture of hydrochloric acid and potassium permanganate in acetonitrile to give moderate to good yields of the corresponding .alpha.-chlorocarbonyl compounds. Mixtures of .alpha.-chloro- and .alpha.,.alpha.- dichlorocarbonyl compounds were obtained for substituted acetophenones. Brominations proceeded similarly with higher yields when the hydrochloric acid was replaced with hydrobromic acid.



		Nicodem (Hive Bee) 08-26-04 12:33 No 527541				Halogenation of aromatics - Chinese method
						Good find Lutesium. When I needed an alpha-chloro-acetophenone I prepared it simply by bubbling chlorine trough the acetophenone in acetic acid, but it is very nice to know that in certain cases you can avoid the nasty Cl₂ gas. These papers by the same authors are also related: (the TIFFs are multipage type, if somebee can't open them I can change them into PDF and upload) Iodination with Potassium Permanganate/Hydroiodic Acid/Acetonitrile Reagent Chen, Jyh-An ; Lin, Ching-Shan ; Liu, Lilian Kao Journal of the Chinese chemical society 43(1), 1996, pp.95-99 http://nr.stic.gov.tw/ejournal/ChiChemSociety/1996/EJ52-1996-95.tif Abstract: Iodination of various aromatic amines proceeds smoothly with a preformed homogeneous mixture of hydroiodic acid potassium permanganate in acetonitrile. para- Substituted products were obtained in high yields (71-78%) within twelve hours at room temperature. With a slight modification of the permanganate, hydroiodic acid and substrate ratio, iodination of alkynes to vic-diiodoalkenes can be carried out at 60.degree.C in 65-87% yield. Reaction of Aromatic and Unsaturated Compounds with the Potassium Permanganate/HCl (HBr) Acetonitrile Reagent Liu, Lilian Kao ; Lin, Ching-Shan Journal of the Chinese chemical society 43(1), 1996, pp.61-66 http://nr.stic.gov.tw/ejournal/ChiChemSociety/1996/EJ52-1996-61.tif Abstract: Addition of hydrochloric or hydrobromic acid to a solution of potassium permanganate in acetonitrile produced a homogeneous mixture, which is suitable for laboratory chlorination or bromination, respectively. Aromatic compounds more reactive than alkylbenzenes can be chlorinated or brominated without additional catalyst. Alkenes and alkynes give the corresponding vicinal dihaloalkanes and vinyl halides. All reactions complete within two hours under mild condition (25-60.degree.C) with excellent to moderate yields. “The real drug-problem is that we need more and better drugs.” – J. Ott



		Kinetic (Hive Bee) 08-26-04 12:43 No 527547				Halogenations with HX and permanganate (Rated as: excellent)
						Edit: Aagh, you beat me to it Nicodem! How did you have these extra papers too?! At least I have them in PDF. Oh well, someone feel free to delete my post/Edit Great find lutesium! For a while I had been wondering whether this reaction would be possible. I would like to try something similar on propiophenone, with permanganate and a halide salt in glacial acetic acid. My idea was based on the Novel Bromination Method for Anilines and Anisoles Using Ammonium Bromide and H2O2 in Acetic Acid (../rhodium /aromatic.bromination.nh4br-h2o2.html). Here is the article in PDF, as well as two other related articles by the same authors (halogenation of arenes with the same permanganate-HX system) which I found a few weeks ago: *A Convenient Halogenation Procedure for the Preparation of alpha-Halocarbonyl Compounds* Sheng-Fan Cheng, Ching-Shan Lin and Lilian Kao Liu* Journal of the Chinese Chemical Society, 1997, 44, 309-312 Abstract Except for substituted acetophenones (p-Y-C₆H₄COCH₃, Y=H, Br, CH₃O), simple ketones, beta-ketoesters and 1,3-diketones reacted smoothly with a preformed homogeneous mixture of hydrochloric acid and potassium permanganate in acetonitrile to give moderate to good yields of the corresponding alpha-chlorocarbonyl compounds. Mixtures of alpha-chloro- and alpha,alpha-dichlorocarbonyl compounds were obtained for substituted acetophenones. Brominations proceeded similarly with higher yields when the hydrochloric acid was replaced with hydrobromic acid. Reaction of Aromatic and Unsaturated Compounds with the Potassium Permanganate/HCl (HBr) Acetonitrile Reagent Lilian Kao Liu* and Ching-Shan Lin Journal of the Chinese Chemical Society, 1996, 43, 61-66 Abstract Addition of hydrochloric or hydrobromic acid to a solution of potassium permanganate in acetonitrile produced a homogeneous mixture, which is suitable for laboratory chlorination or bromination, respectively. Aromatic compounds more reactive than alkylbenzenes can be chlorinated or brominated without additional catalyst. Alkenes and alkynes give the corresponding vicinal dihaloalkanes and vinyl halides. All reactions complete within two hours under mild condition (25-60°C) with excellent to moderate yields. Iodination with Potassium Permanganate/Hydroiodic Acid/Acetonitrile Reagent Jyh-AnChen, Ching-Shan Lin and Lilian Kao Liu* Journal of the Chinese Chemical Society, 1996, 43, 95-99 Abstract Iodination of various aromatic amines proceeds smoothly with a preformed homogeneous mixture of hydroiodic acid potassium pennanganate in acetonitrile. para-Substituted products were obtained in high yields (71-78%) within twelve hours at room temperature. With a slight modification of the permanganate, hydroiodic acid and substrate ratio, iodination of alkynes to vic-diiodoalkenes can be carried out at 60^oC in 65-87% yield.