Alkaline decomposition

Exchange of hydrogen in alkaline solution was reported by Franke and M5nch and subsequently confirmed but attributed to exchange of phosphite formed by alkaline decomposition. A study by proton nmr methods reports simple first-order dependence on the concentrations of HjPOJ and OD. At 25°C and H = 2.0, the rate parameters are k = (6.0+0.7)10 l.mole . sec ( a = 18.9 0.5 kcal.mole ). Reaction of D2POJ and OH has k = (1.92 0.1)10 l.mole sec ( a = 18.7 kcal.mole ). It is suggested that there may be general base catalysis, from qualitative observations of the effect of phosphate. 

In alkaline solutions, hypophosphite decomposes slowly, liberating hydrogen 

The kinetics of this reaction have been studied for 1-6 M NaOH from 60-90°C and it is reported to be first order in hypophosphite but second order in hydroxide ion, viz. 

Hence it has been concluded that the rate-determining step involves removal of the two phosphorus-bound protons. The energy of activation (24 kcal.mole ) decreases with increasing alkalinity, probably due only to a salt effect. The decomposition has also been examined in the presence of nickel and cobalt, which apparently introduce heterogeneous catalysis . 

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C7H6O4. Crystallizes with IH2O m.p. 199" C. It occurs in the free state in the onion and other plants is a constituent of one group of tannins, and is a product of the alkaline decomposition of resins. 

Decomposition with Bases. Alkaline decomposition of poUucite can be carried out by roasting poUucite with either a calcium carbonate—calcium chloride mix at 800—900°C or a sodium carbonate—sodium chloride mix at 600—800°C foUowed by a water leach of the roasted mass, to give an impure cesium chloride solution that is separated from the gangue by filtration (22). The solution can then be converted to cesium alum [7784-17-OJ, CS2SO4 Al2(S0 2 24H20. Extraction of cesium from the poUucite is almost complete. Solvent extraction of cesium carbonate from the cesium chloride solution using a phenol in kerosene has also been developed (23). 

Since alkaline decomposition of p-toluenesulfonylhydrazones of steroid 12-ketones leads directly to 14(13 I2) jr e >-13(17)-enes whereas solvolysis of 12j5-mesylates gives mixtures of 13(18)- and 13(17)-enes, the former approach is preferred for the preparation of C-nor-D-homosteroids. If the particular system under consideration is not stable to base at elevated temperatures, the milder solvolysis method could be used. Either approach starts with a 12-oxygenated steroid. Additional base-stable functional groups should be compatible under the conditions for the rearrangement process. 

One of the first reports involving vinyl diazonium ions and possible vinyl cations is the work of Newman and co-workers (107) on the alkaline decomposition of 3-nitroso-2-oxazolidones, 132. When an aqueous suspension or... 

Scheme VIII. Alkaline Decomposition of 3-Nitroso-2-oxazolidones.

More recently, such vinyl cations generated by the alkaline decomposition of 3-nitroso-2-oxazolidones have been trapped by halogens to give vinyl halides as products (108). It has been suggested that unsaturated carbenes, RjC=C , may be the intermediates in the basic decomposition of 132 (109). Indeed, when 132 (Ri=R2=CH3, R3=H) was treated with lithium ethoxide in the... 

Figure 4. Isokinetic relationship in the coordinates log versus log k, with k, at three different temperatures alkaline decomposition of Malachite-Green-like dyestuffs (186, 187).

Reactions of Phosphonium Salts.- Interest continues in the effects of solvent on the rate of alkaline decomposition of phosphonium salts. It has now been shown that, in the respective reactions of hydroxide ion and methoxide ion with tetraphenyl-phosphonium bromide in mixtures of DMSO and methanol, the rates of the reactions increase as the proportion of the dipolar aprotic... 

Butyl diazoacetate has been prepared by the present method, by alkaline decomposition of /-butyl N-nitroso-N-acetylgly-cinate/ and by diazotization of /-butyl glycinate.7... 

Trimethylsilyldiazomethane, as a stable and safe substitute for hazardous diazomethane, is useful both as a reagent for introducing a Cj-unit and as a C-N-N synthon for the preparation of azoles. Many methods are described in the literature for the preparation of trimethylsilyldiazomethane, including the trimethylsilylation of diazomethane (7-74S), the alkaline decomposition of N-nitroso-N-(trimethylsilylmethyl)amides (25-61%) and the diazo group transfer reaction of trimethylsilylmethyllithium with p-toluenesulfonyl azide (38%). The present modified diazo group transfer method appears to be the most practical, high-yield, and large scale procedure for the preparation of... 

Hydroxylamine is unstable as a free base. It is prepared from hydroxylamine hydrochloride, NH20H HC1, which is obtained by electrolytic reduction of ammonium chloride solution. The hydrochloride undergoes alkaline decomposition to hydroxylamine, which is collected by vacuum distdlation. 

Reaction of phenyl isocyanates with phenylsulfonamides, and the alkaline decomposition to the diphenylureas [97]. 

The alkaline decomposition of 2-(N-nitroso)acetamido-2-deoxyhexoses provides a preparatively useful route to acetylenic sugar derivatives.217a,217b... 

The most extensive quantitative examination of the alkaline decomposition of nitrocellulose has been carried out by Kenyon and Gray [48]. 

There are several other examples of the use of indene derivatives as a source of isocoumarins. Alkaline decomposition of the cyclic peroxide (507), produced by ozonolysis of indene itself, yields a phenylacetaldehyde (57JA3165). Treatment of these aldehydes with acid gives access to isocoumarins which are unsubstituted in the pyranone ring (65JIC211). 

Alkaline breakdown of monazite. —The flowsheet for the process is given in Fig. 5. For this process it is necessary to remove calcium from the monazite by boiling the mineral with nitric or hydrochloric acid. It has long been known that monazite can be attacked by alkali. Rohden and Peltier [149] have shown the practical applicability of the alkali process for monazite decomposition. The optimum conditions necessary for alkaline decomposition of monazite have been extensively studied by Kaplan and his coworkers [150—153]. 

The formation of ammonia always takes place. When heated with metal hydroxides some ketoximes partially regenerate ketones to liberate ammonia (54MI1). Nevertheless, cyclohexanone does not seem to be an intermediate product since, in a special run carried out with a mixture of cyclohexanone and ammonia (under otherwise equal conditions), a complicated mixture of products, containing no alcohol 110 was obtained. Cyclohexanone itself was nearly inert in runs with LiOH, NaOH and tetrabutylammonium hydroxide, which provides evidence against its formation as an intermediate in the alkaline decomposition of the oxime. 

The mechanism of the alkaline decomposition of methyl ethynyl ketone—to acetate and ethyne—has been probed using AMI calculations.125... 

Attachment of substituents incompatible to ozone required a different general synthetic route. For example, allyl acid 59 displayed poor chemoselectivity on exposure to ozone. Contrary to reports of alkaline decomposition of the lactone-acetal-peroxide functionality,16 the enolate of the prefabricated tetracycle 42 could be generated at low temperature and alkylated. As a notable example, this methodology produced a single allylated tetracycle, the a-epimer 59. This initial alkylation product was unchanged after prolonged acid treatment, and structure 57 was... 

The sensitivity of phenyl glycosides to alkali has been evident for over a century. As early as 1844, Bouchardat described the alkaline decomposition of salicin, a glucoside occurring in the leaves and bark of the willow (Salix helix). However, it remained for Tanret to discover the unique... 

The discovery by Kuhn and Low13 that picrocrocin (VIII) is degraded by aqueous alkali to D-glucose and safranal (IX) indicated a mechanism for the alkaline decomposition of this class of glycoside. 

D-glucoside tetraacetate (XII) could not be deacetylated without destruction of the D-glucosidic linkage. The products of alkaline decomposition of XI and XII have not been determined. 

Diazo-l, 8-, 3,6-, and 4,5-diazafluorenes are obtained by alkaline decomposition of the respective 9-tosylhydrazones. Photolysis of these diazo compounds yields reactive carbenes whose properties and reactions were investigated by Schuster and Li <86JOC3806, 87JOC3975) and by Durr and coworkers <89TL1935>. 

The formation of vinyl cations by deamination of vinyl amines in neutral media, is therefore not established and the possibility that a carbene intermediate is actually involved must be considered. Thus, the products of the alkaline decomposition of N-nitroso-oxazolidones 109 were earlier explained (Newman and Kutner, 1951 Newman and Weinberg, 1956) in terms of a mechanistic scheme involving vinyl cation intermediates (equation 19). Such a scheme has recently been... 

Various decomposition reactions of heterocyclic cations in aqueous solution are expected to proceed via pseudobase intermediates. These intermediates have been established for the alkaline decomposition of the pyridinium ring of nicotinamide adenine dinucleotide300 and for various solution transformations of flavin-derived cations.112,113,301-303 Nucleophilic substitution by hydroxide ion in various heteroaromatic cations almost certainly proceeds via the appropriate pseudobase tr-complexes.304,305... 

Similar findings were obtained for the alkaline decomposition of triarylsulfonium halides with ethoxide ion in aqueous ethanol at 120 °C [71], The results indicate that the decomposition rate is decreased about 10 -fold by increasing the water content from 2.3 to 98.2 cmol/mol [71]. 

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