Acetoxime, preparation

In order to prepare pure acetoxime (Note 4), the procedure is modified in the following way After neutralizing the solution of acetoxime formed after the addition of acetone, the oily layer is separated and the aqueous solution shaken with two or three 150-cc. portions of benzene. The oil and benzene solutions are mixed, the water thereby thrown out is removed, and the oil fractionally distilled with the use of a column, the portion boiling 133-136° being collected as pure acetoxime. This product, which weighs 420-480 g., solidifies in the receiver to colorless needles melting at 60-61°. The foreruns and aqueous liquors are best distilled with steam and the distillate converted into hydroxylamine hydrochloride as above, whereupon 75-90 g. of pure salt is obtained. 

The salt was repeatedly precipitated by alcohol and dissolved in water. A similar or identical salt having the constitution SP(OH)2(ONH4) was prepared by the action of phosphorus pentasulphide on acetoxime in carbon disulphide solution. The part insoluble in CS2 was extracted with alcohol, boiled and crystallised from cold water in monoclinic prisms.7... 

A series of predominantly ID assemblies have been prepared by Aakeroy and co-workers using silver(I) ions [50], which have a tendency to adopt a linear two-coordinate geometry (i.e. AgLj building blocks, cf. VII, XVII, XVIII). These assemblies are obtained with ligands L = pyridine-4-carboxamide (isonicotinamide) [50a], pyridine-3-aldoxime [50b] and pyridine-3-acetoxime [50b], when using... 

Oximes add hydrogen cyanide to form a-hydroxylaminonitriles. The yields are greatly improved by substituting a sodium cyanide-phosphate buffer for liquid hydrocyanic acid, as in the preparation of a-hydroxyl-aminoisobutyronitrile (67%) from acetoxime. ... 

I) Preparation of Oximes. (1) Acetoxime. Dissolve 1 g of hy-droxylamine hydrochloride in 2 ml of water. Add 3 ml of 20 per cent sodium hydroxide solution (or 0.6 g of solid sodium hydroxide dissolved in 2 ml of water). Add 2 ml of acetone, cork securely, and shake vigorously for one minute. Allow to stand overnight. If crystals do not appear, seed with a minute amount of the oxime, and allow to stand for some time. Filter the crystals with suction and allow to dry. Place in a tube or bottle immediately. 

When sulfuryl amide or imidodisulfamide is heated with strong sodium hydroxide solution, the sodium salt of amidosulfonic acid results. The free acid itself may be prepared in various ways for example, from urea and sulfuric acid, from many adducts of sulfur trioxide and ammonia, from hydroxylammonium salts and sulfur dioxide, or from SO and acetoxime. Amidosulfonic acid, which is colorless and melts at 205° with decomposition, has, as Baumgarten supposed (13), the structure (LXXXVII). 

Sulfamic acid, NH2SO3H, is an ammonoaquosulfuric acid in which one of the hydroxyl groups of sulfuric acid has been replaced by the isosteric amido group. It is prepared commercially by the interaction of fuming sulfuric acid and urea. This method is not readily adaptable to laboratory preparation on a small scale. Consequently, the sulfur dioxide-hydroxylamine reaction is recom-mended.H Sulfamic acid may also be obtained by the action of sulfur dioxide upon certain compounds which yield hydroxylamine such as acetoxime. The recommended procedures are modifications of older processes and involve the use of sulfur dioxide under pressure upon aqueous solutions of hydroxylammonium salts and compounds yielding hydroxylamine. 

An attempt to reproduce synthesis of 0-vinyl oximes according to the protocol [326] from oximes and acetylene (generated in situ from calcium carbide) in aqueous medium has led to pyridines instead of the expected products [174], For example, 2,4,6-trimethylpyridine in -10% yield is prepared from acetoxime (Scheme 1.150). 

The condensation of sulphamide and diethyl oxalate produces 3,4-dihydroxy-1,2,5-thiadiazole 1,1-dioxide as the dipotassium salt in high yield. The free acid (177) is an excellent precursor for the preparation of other functional derivatives, and for building up fused ring systems incorporating the 1,2,5-thiadiazole 1,1-dioxide structure (see below). The two isomeric benzothiadiazole acetoximes (178) and (179) undergo the Beckmann reaction, resulting in the fission of their carbocyclic ring. This provides an effective synthesis of novel ajS-unsaturated 1,2,5-thiadiazoles (180 X = COaH, Y = CR=CHCN X =... 

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