Phosphoric acid oxidative cleavage

As expected, the reaction of the lithium salts of phosphonates with oxygen results in the formation of dialkyl phosphoric acids-8 and carbonyl products i.e. the cleavage of the C-P bond takes place (, 5). However, when the halomagnesiurn salts of phosphonates Z were oxidized, a-hydroxyphosphonates 2 were formed. 

Starch pastes irradiated with 130,000 V, 15 mA X-rays lost their viscosity, and there was concurrent decrease of iodine-binding ability and pH. Other properties measured after such treatment point to dextrinization and oxidation of starch.78-79 Other results of such irradiation is the cleavage of phosphoric acid esters from glucose units of potato starch. This effect is observed at 50,000 V and 8 mA as well as at 150,000 V and 12 mA. The effect of X-ray irradiation is similar in this respect to irradiation with 7-rays, whereas neither sonication with ultrasound nor exposure to UV light evoke such effects.5 Starch irradiated by X-rays, contains free radicals, and thus the presence of free radicals in starch provides evidence of previous irradiation. 

However, from economic and environmental point of view both USA and Japan use the propylene alkylation route, as this method of manufacture is more amenable to continuous operations with recycle stream. The alkylation with propylene and isomerization are carried out upto 240° C with traditional solid phosphoric acid (SPA) catalyst and more recently with anhydrous AICI3 catalyst. Final catalytic oxidation at 90-110°C gives the hydroperoxide, as in cumene and cymene processes, which on cleavage with dilute sulfuric acid gives 2-naphthol in high overall yield. [53]... 

Phosphorus is known to be an oxidation protector and a fire retardant for carbonaceous materials [111-119]. Phosphoric acid is used as an activating agent for activated carbons. It promotes bond cleavage reactions and the formation of phosphate and fwlyphosphate bridges that expand and crosslink the carbon matrix, driving to an accessible pore structure after removal ofthe acid [118,119]. 

Soil The sulfoxide group is oxidized to the sulfone and oxidative and hydrolytic cleavage of the side chain gives dimethylphosphoric and phosphoric acids (Hartley and Kidd, 1987). Oxamyl was degraded by the microorganism Pseudomonas putida in a laboratory study using cultured bacteria (Zeigler, 1980). 

Diiodopropane reacts similarly to give isopropyliodide and byproducts) One mole of titratable iodine is produced for each alkylene oxide unit. The liberated iodine is titrated with sodium thiosulfate solution. Alternatively, the cleavage products may be determined by gas chromatography, permitting distinguishing between oxyethylene and oxypropylene content. A number of studies of this reaction have appeared. They indicate that only about 80% yield is obtained in the reaction of PO units with HI (15). For practical reasons, the unstable HI reactant is usually replaced with KI and phosphoric acid (12). 

N-Acyliminium ions are considerably more electrophilic than the iminium ions described earlier. As a result, their cyclizations have been used extensively in the service of complex molecule synthesis [104, 119]. A classic application was reported by van Tamelen m route to yohimbine (136), historically one of the most important members of the complex indole alkaloids (Scheme 11.21) [120], In the key cyclization event, oxidative cleavage of the vicinal diol in 133 afforded crude lactol 134. Treatment of 134 with phosphoric acid led to cyclization onto the indole, furnishing lactol 135 in 60% yield as a single diastereomer. 

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