6-Hydroxy ethers, decomposition preparation

Sodium azide does not react with carbonyl sulfide to form 5-hydroxy-1,2,3,4-thiatriazole, nor with carboxymethyl xanthates, RO-CS SCH2COOH, to form 5-alkoxy-l,2,3,4-thiatriazoles. The latter, however, could be prepared from xanthogenhydrazides (RO-CS NHNH2) and nitrous acid. They are very unstable and may decompose explosively at room temperature only the ethoxy compound (6) has been examined in detail. This is a solid which decomposes rapidly at room temperature and even at 0°C is transformed after some months into a mixture of sulfur and triethyl isocyanurate. In ethereal solution at 20° C the decomposition takes place according to Eq. (16)... 

Preparation of 2-Hydroxy-4,4 -Diamidinostilbene Dihydrochloride 10 grams of 2-hydroxy-4,4 -dicyanostilbene were suspended in 250 cc of absolute ethyl alcohol and the mixture saturated with dry hydrogen chloride at 0°C. The whole was left for eight days at room temperature. The imino-ether hydrochloride formed was filtered off, washed with dry ether and dried in the air for a short time. It was then added to 250 cc of 10% ethyl alcoholic ammonia and the whole heated for 5 hours at 45°C. The 2-hydroxy-4,4 -diamidino-stilbene dihydrochloride which separated was crystallized from 10% hydrochloric acid. It forms pale yellow needles, MP 357°C (decomposition). 

Preparative photolysis of AETSAPPE (0.25 M aqueous solution) at 254 nm (Rayonet reactor) resulted in the formation of the disulfide product 2-amino(2-hydroxy-3-(phenyl ether) propyl) ether disulfide (AHPEPED) as the primary photoproduct Photolysis of AETSAPPE at 254 nm (isolated line of medium pressure mercury lamp) resulted in rapid initial loss of starting material accompanied by formation (analyzed by HPLC) of AHPEPED (Figure 12a and 12b) (Scheme IV). Similar results were obtained for photolysis- at 280 nm. Quantum yields for disappearance of AETSAPPE and formation of AHPEPED at 254 nm and 280 nm are given in Table I. The photolytic decomposition of AETSAPPE in water was also accomplished by sensitization ( x =366 nm) with (4-benzoylbenzyl) trimethylammonium chloride (BTC), a water soluble benzophenone type triplet sensitizer. The quantum yield for the sensitized disappearance (Table I) is comparable to the results for direct photolysis (unfortunately, due to experimental complications we did not measure the quantum yield for AHPEPED formation). These results indicate that direct photolysis of AETSAPPE probably proceeds from a triplet state. 

Low-temperature autoxidation of 3,4-dihydro-2//-pyrazoles (e.g. 10, R = Me) provides unstable a-azo hydroperoxides (Scheme 30) [61a,bj 3,4-dihydro-2//-pyrazoles that are inert towards autoxidation (cf. 10, R = Ph) can be converted to hydroperoxides by reaction with singlet oxygen (photooxygenation) at 0- 5 °C [61b], a-Azo hydroperoxides readily decompose at room temperature to -keto radicals which can be entrapped with oxygen to furnish 3-hydroxy-1,2-dioxolanes (e.g. 11 —> 12, Scheme 30) [61cj. The preparation and thermal decomposition of several ether, silyl ether and ester derivatives of 3-hydroxy-1,2-dioxolanes have been reported [62]. 

The alkaloid Syphilobin F,a2-substituted-3-pyridinol(see Section VI., p. 861), is 0-methylated by diazomethane in diethyl ether-benzene in 43% yield. Anhydro-3-hydroxy-N-roethylpyridiniumhydroxide (XII-S67) can be formed by the reaction between 3-pyridinol and diazomethane, by the reaction of Mmethyl-3-hydroxypyridinium chloride with anhydrous sodium carbonate and by thermal decomposition of 3-methoxypyridine iodomethylate. However, its preparation from the dimer complex of Mmethyl-3-hydroxypyridinium iodide (XII-S68) by treatment with silver oxide was the most convenient method. It has also been prepared from the quaternary iodide. ... 

---