Oximes s. Beckmann rearrangement

Beckmann rearrangement of cvc7ohexanone oxime. M.p. 68-70 C, b.p. I39 C/12 mm. On healing it gives polyamides. Used in the manufacture of Nylon[6]. Cyclohexanone oxime is formed from cyclohexane and niirosyl chloride. U.S. production 1978 410 000 tonnes, capryl alcohol See 2-octanol. caiH Uc acid See oclanoic acid. 

Ingredients. Nylon-6 is produced commercially from caprolactam [105-60-2] which is the most important lactam industrially. AH industrial production processes for caprolactam are multistep and produce ammonium sulfate [7783-20-2] or other by-products. Approximately 95% of the world s caprolactam is produced from cyclohexanone oxime [100-64-1] via the Beckmann rearrangement (144). The starting material for cyclohexanone can be... 

Activation of the Beckmann rearrangement of the enantiopure spirocyclic keto oximes (—)-(12) and (—)-(13) has been initiated with four acidic promoters.17 In two cases (PPE and PPSE), concerted [1,2]-shift of the anti carbon operates exclusively. This is not the case with PPA or Eaton s reagent, although optical activity is fully maintained in these ring expansions. 

Of the processes based on modification of the conventional route, only Stamicarbon s hydroxylamine phosphate oxime (HPO) process completely avoid all production of ammonium sulfate before the Beckmann rearrangement. The steps in the HPO process are listed below and shown in Figure 21.146, 264 ... 

These may be prepared by reduction of appropriate nitro compounds. The free amines are unstable, but can be isolated as the tin(IV) chloride double salts, and give stable acetyl derivatives. 2-Acetamidothiophene has been prepared by a Beckmann rearrangement of the oxime of 2-acetylthiophene (63AHC(l)l). 2-Aminothiophene hydrochloride was isolated in 84% yield when c/s-4-benzhydrylthiocrotononitrile was treated with hydrogen chloride gas in dry ether (equation 46) (69JHC147). 

The abnormal Beckmann rearrangement displayed by the oxime of 17-oxo-5a-androstan-3/3-yl acetate (248) to yield the 13,17-seco-nitrile (249) has provided the key step in a synthetic route to 17-oxo-18-nor-5a,13/8-androstan-3/S-yl acetate and its 13a-epimer.114 The reaction sequence is shown in Scheme 12. The 17-ketone (248) was converted via its oxime into the seco-nitrile in a yield of 52%. Treatment of the oxime by the more conventional toluene-p-sulphonyl chloride reagent... 

Current production of s-caprolactam is mainly based on the reaction of cyclohexanone with hydroxylamine and subsequent rearrangement of the intermediate oxime. Undesirable ammonium sulfate is co-produced well in excess of s-caprolactam, i.e., 0.9-2.9 kg in the oximation step and 1.5-1.8 kg in subsequent Beckmann rearrangement, for 1 kg of product. The salt, of little commercial value, is sold for use in fertilizers or can be incinerated for the recovery of sulfur (Figure 23). 

The chemistry of such bridged naphthalenes-benzomorphans and some related compounds has been reviewed previously.<1 3) The first synthesis of a benzomorphan was achieved by Barltrop(4) however, prior to that synthesis, Schopf,(5) in his investigations of the structure of morphine, had isolated the benzomorphan, 2, from a thionyl chloride-induced, second-order Beckmann rearrangement of dihydrocodeinone oxime, 1. Reinvestigation(5a,5b) of the Beckmann rearrangement and a study of the Schmidt reaction of 6-oxomor-phinans confirmed Schopf s work and led to the isolation of the anticipated lactam (2a). 

J. C., Beckmann rearrangements of Mannich base and related oximes, J. Chem. S[Pg.81]

Oximes of cyclojjentanone and cyclohexanone undergo the Beckmann rearrangement to cyclic amides from which amino acids may be obtained, e.g., S-aminovaleric acid (71-80%) and e-aminocaproic acid (92%). ... 

Dimethylaniline has been prepared by reduction of the corresponding nitro compound, either chemically or catalyti-cally. It has been prepared from 3,4-dimethylphenol by heating with ammonia, ammonium bromide, and zinc bromide from w-toluidine hydrochloride by alkylation with methanol at high temperatures from anhydro-4-amino-2-methylbenzyl alcohol by dry distillation from calcium hydroxide from 2-methyl-S-aminobenzyl alcohol by reduction with sodium from 2-methyl-5-nitrobenzyl chloride and 2-methyl-S-nitrobenzyl acetate by catalytic reduction from o-xylene by direct amination with hy-droxylamine hydrochloride in the presence of aluminum chloride and from 3,4-dimethylacetophenone by the Beckmann rearrangement of the oxime.i" The present method has been published. ... 

---