Named rearrangements Beckmann

Zeolites have also been described as efficient catalysts for acylation,11 for the preparation of acetals,12 and proved to be useful for acetal hydrolysis13 or intramolecular lactonization of hydroxyalkanoic acids,14 to name a few examples of their application. A number of isomerizations and skeletal rearrangements promoted by these porous materials have also been reported. From these, we can underline two important industrial processes such as the isomerization of xylenes,2 and the Beckmann rearrangement of cyclohexanone oxime to e-caprolactam,15 which is an intermediate for polyamide manufacture. Other applications include the conversion of n-butane to isobutane,16 Fries rearrangement of phenyl esters,17 or the rearrangement of epoxides to carbonyl compounds.18... 

Of course, other reaction types have been also investigated more recently, such as the Beckmann rearrangement [247,277,278] or ethylbenzene disproportionation [279, 280], just to name a couple. In situ NMR methods are expected to play a vital role in the future science of heterogeneous catalysis. 

Beckmann, E. Chem. Ber. 1886, 89, 988. Ernst Otto Beckmann (1853—1923) was bom in Solingen, Germany. He studied chemistry and pharmacy at Leipzig. In addition to the Beckmann rearrangement of oximes to amides, his name is associated with the Beckmann thermometer, used to measure freezing and hoihng point depressions. Mazur, R. H. J. Org. Chem. 1961,26, 1289. 

The common name caprolactam comes from the original name for the Ce carboxylic acid, caproic acid. Caprolactam is the cyclic amide (lactam) of 6-aminocaproic acid. Its manufacture is from cyclohexanone, made usually from cyclohexane (58%), but also available from phenol (42%). Some of the cyclohexanol in cyclohexanone/cyclohexanol mixtures can be converted to cyclohexanone by a ZnO catalyst at 400°C. Then the cyclohexanone is converted into the oxime with hydroxylamine. The oxime undergoes a very famous acid-catalyzed reaction called the Beckmann rearrangement to give caprolactam. Sulfuric acid at 100-120°C is common but phosphoric acid is also used, since after treatment with ammonia the by-product becomes... 

Beckmann rearrangements that go with fragmentation are sometimes called anomalous or second-order1 Beckmann rearrangements. You should not use the second of these names and, in any case, Beckmann fragmentation is much better than either. 

Into this group fall the named oxidation rearrangement reactions which proceed with carbon-carbon bond cleavage and 1,2-transfer of an alkyl group to a heteroatom, such as the Baeyer-Villiger reaction (discussed in Chapter 5.1, this volume) and the Beckmann reaction (found in Chapter 5.2, this volume) of ketones, as well as the Hofmann reaction/Schmidt reaction/Curtius reanangement of carboxylic acid derivatives. The two examples discussed here involve related reactions of alcohols. 

ITQ-2 zeolite prepared by delamination of MCM-22 precursor, is formed by disordered individual sheets of crystalline zeolitic layers in where the Bronsted acid sites are of zeolitic nature and the vast majority of them aecessible to large molecules. The delaminated zeolite combines the acid characteristic of microporous zeolites with accessibility of the sites of mesoporous Al/MCM-41 and amorphous silica-alumina. The superior catalytic performance of delaminated zeolites compared to conventional zeolites and Al/MCM- 1 is examplified for reactions involving large reactant molecules, namely the preparation of dimethyl acetals, the Beckmann rearrangement of bulky cycloalkanone oximes and hydroxylation of aromatics. 

Beckmann rearrangement The chemical conversion of a ketone oxime into an amide, usually using sulphuric acid as a catalyst. The reaction, used in the manufacture of nylon and other polyamides, is named after the German chemist Ernst Beckmarm (1853-1923). 

An important molecular rearrangement of oximes to amides discovered by Ernst Otto Beckmann in 1886 and so named in his honor. The modem version uses one of the most powerful add reagents used in organic chemistry, triflic acid. 

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