Mercuric oxide, hydrolysis

Acid amides have weakly amphoteric properties, and thus give salts such as CjHsCONHj.HCl with strong acids, and salts of the type C HsCONHNa with strong bases. These compounds have to be prepared at low temperatures to avoid hydrolysis, and are difficult to isolate. The mercury derivatives can, however, usually be readily prepared, because mercuric oxide is too feebly basic to cause hydrolysis of the amide, and the heavy mercuric derivatives crystallise well. 

Difluoroethanol is prepared by the mercuric oxide cataly2ed hydrolysis of 2-bromo-l,l-difluoroethane with carboxyHc acid esters and alkaH metal hydroxides ia water (27). Its chemical reactions are similar to those of most alcohols. It can be oxidi2ed to difluoroacetic acid [381-73-7] (28) it forms alkoxides with alkaH and alkaline-earth metals (29) with alkoxides of other alcohols it forms mixed ethers such as 2,2-difluoroethyl methyl ether [461-57-4], bp 47°C, or 2,2-difluoroethyl ethyl ether [82907-09-3], bp 66°C (29). 2,2-Difluoroethyl difluoromethyl ether [32778-16-8], made from the alcohol and chlorodifluoromethane ia aqueous base, has been iavestigated as an inhalation anesthetic (30,31) as have several ethers made by addition of the alcohol to various fluoroalkenes (32,33). Methacrylate esters of the alcohol are useful as a sheathing material for polymers ia optical appHcations (34). The alcohol has also been reported to be useful as a working fluid ia heat pumps (35). The alcohol is available ia research quantities for ca 6/g (1992). 

Mercuric Acetate. Mercuric acetate/7ti(9(9-27-7/, Hg(C2H202)2, is a white, water-soluble, crystalline powder, soluble in water and many organic solvents. It is prepared by dissolving mercuric oxide in warm 20% acetic acid. A slight excess of acetic acid is helpful in reducing hydrolysis. 

Guaiacols. Cresote, obtained from the pyrolysis of beechwood, and its active principles guaiacol [90-05-1] (1) and cresol [93-51-6] (2) have long been used ia expectorant mixtures. The compounds are usually classed as direct-acting or stimulant expectorants, but their mechanisms of action have not been well studied. Cresol is obtained by the Clemmensen reduction of vanillin (3), whereas guaiacol can be prepared by a number of methods including the mercuric oxide oxidation of lignin (qv) (4), the ziac chloride reduction of acetovanillone (5), and the diazotization and hydrolysis of o-anisidine (6). 

The more generally known mercuric oxide-mercuric chloride hydrolysis 2 may also be used, and in the present case it gives a yield of about 90%. The reductive desulfurization of Part E is also based on the work of Mukaiyama.12 It is clearly superior to Raney nickel desulfurization, which gives only 36-45% of 3-benzylindole. 

The iodine atom in the monoiodide may be replaced by other groups and, by reaction with silver salts, for example, As(CF3)2CN (b.p. 89 5°) and As(CFg)2SCN (b.p. 116—118°) are readily prepared. Reaction of the monoiodide with mercury gives the cacodyl As2(CF3)4 (b.p. 106 to 107°), while with mercuric oxide the oxide As2(CF3)40 (b.p. 95—97°) is formed. The chemistry of these substances has not yet been studied in detail, but it is noteworthy that hydrolysis of the perfluorocacodyl gives both fluoroform and fluoride, which parallels the observations made on the diphosphine. 

Alternative methods for removing 1-propenyl groups under non-acidic conditions have been reported these include reaction with alkaline potassium permanganate solution,204,205 ozonolysis followed by alkaline hydrolysis,204 205 treatment with a mercuric chloride-mercuric oxide reagent,206,207 and treatment with palladium on activated charcoal in a hydroxylic solvent containing a trace of an acid.2070 The last procedure is a combined isomerization-hydrolysis, but the isomerization step may be independently achieved by omission of the acid.2070,2076... 

Mercury fulminate crystallizes from water as a yellow coloured product containing H20 (Shishkov [19]). It was believed at first that the yellow colour is due to the presence of mercuric oxide resulting from the hydrolysis of the fulminate. It is now considered that this colour should be ascribed to the formation of products not fully defined and partly to the mercuric salts of metafulminuricacid (p. 134).Furthermore on boiling in water, the hydrolysis of mercury fulminate may be fairly extensive. 

Hydrolysis of the oxazolidinone 236 gave the corresponding amino alcohol, which without isolation was coupled with the sugar 4-isothiocyanate 2653 to provide the thiourea 452 (Scheme 67).105 Cyclization of 452 to the isourea 453 was carried out with yellow mercuric oxide, and the resulting oxazoline 453 was debenzylated to give... 

Oxidative hydrolysis of 2-aeyl-l -dithiane derivatives. A study of the hydrolysis of 2-acyl-1,3-dithianc derivatives by mercuric chloride (HgCl ) has been published. However, hydrolysis of 2-acyl-l,3-dithianes is slow. In this case use of N-haiosuccini-mide reagents is recommended. Either N-bromo uccinimide or N-chlorosuccinimidc-silver nitrate is suitable for oxidative hydrolysis of 1,3-dithiane derivatives. The N-halosuccinimide reagents are useful for hydrolysis of 2-acyl-1,3-dithianes to 1,2-dicarbonyl compounds. 

Of from allyl iodide mercuric oxide (Refs 1 3). Diallylether is also obtd, along with other products, by hydrolysis of allyl chloride in a glass-packed tube (Ref 4). Niederl et al ( Ref 2) reported that diallylether reacted with m-cresol, in the presence of a small quantity of 804, with explosive violence Refs Beil 1, 438 [477] U883I 2) J.B. Niederl et al, JACS 53, 3393-94 (I931) 3) Thorpe 1(1937), 258... 

For the hydrolysis step, for example (13) - (14), Corey used mercuric chloride-mercuric oxide in aqueous methanol, while Brook used a modification of Wolfrom s procedure (1, 654, ref. 14), using acetone-benzene-water as solvent. For volatile ketones, Brook prefers DMSO-water as the solvent system. 

---