Acid chlorides oximes, hydrogenation

See Ethyl 2-formylpropionate oxime Hydrogen chloride Sulfuric acid Cyclopentanone oxime See other CATALYTIC IMPURITY INCIDENTS, OXIMES... 

The oxime 7, prepared from salicyl aldehyde, is converted with iV-chlorosuccinimide into the hydrox-amic acid chloride 8. From this, the nitrile oxide is obtained with KHCO3, which reacts regioselec-tively with styrene to give the 3,5-diaryl-4,5-dihydroisoxazole 9. Catalytic hydrogenation leads to the y -hydroxy ketone 10, which on acid-catalysed cyclodehydration gives the flavanone 11. 

Thebainone (Schopf), CigHjjOgN. This substance, which must be distinguished from Pschorr s thebainone (metothebainone of Schopf (see p. 248) ), is formed, along with the latter in the reduction of thebaine by stannous chloride in hydrochloric acid, and was isolated by Schopf and Hirsch. Its prior isolation by Pschorr, as confirmed by Morris and Small, has been referred to already. It crystallises with 0-5 HjO, has m.p. 151-2°, yields a hydriodide, m.p. 258-9°, methiodide, m.p. 223°, and an oxime, m.p. 185-6°. On catalytic hydrogenation it yields dihydrothebainone (LI), and can be degraded to 3 4 6-triacetoxyphenanthrene, m.p. 165-7°. On this basis formula (XLIX) is assigned to it. The mechanism of the formation of codeinone, thebainone and mefathebainone from thebaine is discussed by Schopf and Hirsch. ... 

On distillation with zinc dust the alkaloid gives an easily hydrogenated pyrrole base, and on dehydrogenation by platinised asbestos at 260-290 it yields (1) an amorphous dehydro-base, which forms an oxime and a methiodide, C17H23O4N. Mel, decomp. 227-8 , and contains a lactone and a methoxyl group, (2) a neutral pyrrole derivative, and (3) an acid giving a dark green colour with ferric chloride (1939). 

The preferred industrial method of carvone synthesis utilizes the selective addition of nitrosyl chloride to the endocyclic double bond of limonene. If a lower aliphatic alcohol is used as solvent, limonene nitrosochloride is obtained in high yield. It is converted into carvone oxime by elimination of hydrogen chloride in the presence of a weak base. Acid hydrolysis in the presence of a hydroxylamine acceptor, such as acetone, yields carvone [88]. 

The main renewable resource for L-carvone is spearmint oil (Mentha spicata), which contains up to 75% of this flavour chemical. There also exists a synthetic process for the manufacturing of L-carvone, which is based on (-t)-limonene, which is available as a by-product of the citrus juice industry as a major component of orange peel oil (Scheme 13.4). The synthesis was developed in the nineteenth century and starts with the reaction of (-t)-limonene and nitrosyl chloride, which ensures the asymmetry of the ring. Treatment with base of the nitrosyl chloride adduct results in elimination of hydrogen chloride and rearrangement of the nitrosyl function to an oxime. Acid treatment of the oxime finally results in l-carvone. 

In the nitrosation of ethyl isopropyl ketone (Preparation 2-4), acetyl chloride is used as a catalyst. While aqueous hydrochloric acid has also been used to catalyze this reaction, anhydrous hydrogen chloride or acetyl chloride evidently is more effective as far as the yield is concerned. To be noted here is that the greater yield is that of the true nitroso compound. However, the secondary carbon atom of the ethyl group is converted into an oxime on nitrosation. 

Reduction of isatin-3-oximes to the corresponding 3-aminooxindole has been carried out using stannous chloride in acetic acid51 or in hydrochloric acid.92 3-Aminooxindole has also been obtained by electrochemical reduction288 and catalytic hydrogenation.169 Reduction... 

Oximes of ketones undergo rearrangement (the Beckmann rearrangement) to amides under the influence of a variety of acidic reagents (e.g. sulphuric acid, hydrogen fluoride, acetic anhydride, phosphorus pentachloride, thionyl chloride, etc.). The process is illustrated by the conversion of benzophenone oxime to benzanilide in the presence of phosphorus pentachloride. 

P-Benzilmoitoxime. The a-oxime is converted into the /J-form by treatment with a solution of hydrogen chloride in benzene (CAUTION) (or ether) at room temperature. From benzene, solvated crystals which melt on rapid heating at about 65 °C are obtained. Removal of benzene of crystallisation in an oven at 50 °C and recrystallisation from carbon disulphide (CAUTION) yields pure /J-benzilmonoxime, m.p. 112°C. The product gives no colour change with aqueous-alcoholic copper acetate solution if it is contaminated with the a-form a greenish colour is produced. (Conversion of the a-form into the / -form may also be effected by boiling in benzene solution in the presence of animal charcoal, which presumably contains adsorbed acidic catalysts.)... 

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