Ethoxy group, cleavage

Animals. 98.5-100% of 14C was excreted within 7 days. The major metabolic routes were deethylation of the 4-ethoxy group, cleavage of the carbamate linkage, acetylation, and finally formation of the glucuronide and sulfate conjugates... 

At neutral to alkaline pH values (7 to 10), the above pathway competes with dealkylation of the ethoxy group (cleavage of the O-P bond, followed by addition of a hydroxyl group), the latter pathway yielding the environmentally stable EA 2192 and ethanol. Although MPA can theoretically be formed slowly by hydrolysis of EMPA, this has not been demonstrated to occur in aqueous solutions (Kingery and Allen, 1995). 

Cleavage of streptomycin with ethyl mercaptan and hydrogen chloride yielded streptidine and a new derivative of streptobiosamine, ethyl thio-streptobiosaminide hydrochloride diethyl mercaptal. Treatment of methyl streptobiosaminide hydrochloride dimethyl acetal with ethyl mercaptan and hydrogen chloride readily yielded the same mercaptal hydrochloride. It thus was apparent that the relationship between these two compounds resided simply in the replacement of methoxy by thio-ethoxy groups on the same carbon skeleton. Acetylation of the mercaptal yielded two anomeric forms of ethyl tetraacetylthiostreptobiosaminide diethyl mercaptal. ... 

Thus, for example, for molar ratio of water/OTES = 0.8, water coiwersion amounts to 94% during the first 15 min and 97.9% in 24 h. At the same time, according to H NMR data, water consumption on cleavage of ethoxy groups amounts to 70% during the first 15 min and 97.9% in 24 h. This testifies to the fact that the hydrolytic reaction according to Eq.l proceeds faster than polycondensation reactions according to Eqs. 2 and 3. 

Zeisel determination. Cleavage of methoxy and ethoxy groups with boiling hydriodic acid, distillation of the alkyl iodide into alcoholic silver nitrate, and gravimetric determination as silver iodide. Alternatively, the alkyl iodide is oxidized to form iodate and the iodine liberated by addition of potassium iodide is titrated. 

Convincing evidence that ester hydrolysis in base proceeds by the second of these two paths, namely, acyl-oxygen cleavage, has been obtained from several sources. In one experiment, ethyl propanoate labeled with 0 in the ethoxy group was hydrolyzed. On isolating the products, all the 0 was found in the ethyl alcohol there was no 0 enrichment in the sodium propanoate. 

CsMes) ] contained both fi-oxo and /t-ethoxy groups originating from cleavage of the diethyl ether solvent. 

The reaction of tabun with nucleophiles is more complex than that of the simple phos-phorylfluoridates. The courses of such reactions are pH dependent and, according to the conditions, cleavage of either the P—N bond or the P—CN bond can predominate , as shown in Scheme 11. At low pH, in aqueous acid, protonation of the basic nitrogen atom leads to initial P—N cleavage with loss of dimethylamine, with further displacement of cyanide and ultimately the ethoxy group (under more forcing conditions). Under basic conditions, cyanide ion is displaced preferentially. At pH 7, the hydrolysis is slow and proceeds by non-selective multiple reaction pathways. 

Selective methoxy group cleavage in presence of the ethoxy aromatic system was accomplished using the procedure described by F. G. Mann and M. J. Pragnell, Chem. Ind., 1386 (1964). 

The determination of alkyl chain distribution of alcohol ether sulfates can be most easily performed by gas chromatography after cleavage of the sulfated ethoxy moiety with hydri-odic acid. This procedure is similar to that described under the analysis of ethoxylated nonionic surfactants. The alkyl iodides from cleavage may also be determined by HPLC (72). An alternative approach requires the decomposition of the sulfate and ethoxy groups with the mixed anhydrides of paratoluenesulfonic and acetic acid, followed by GC determination of the alcohol acetates (73). 

This method is optimized to determine the length of the poly(ethylene oxide) chain in, for example, an ethoxylated alcohol surfactant (11,12). It is also applicable to determination of oxypropylene content and to analysis of other products, such as EO/PO block copolymers (13,14). Quantitative results are not obtained from analysis of alkoxylated amines due to incomplete cleavage of the ethoxy group adjacent to the nitrogen. 

The cleavage proceeds by initial reduction of the nitro groups followed by acid-catalyzed cleavage. The DNB group can be cleaved in the presence of allyl, benzyl, tetrahydropyranyl, methoxy ethoxy methyl, methoxymethyl, silyl, trityl, and ketal protective groups. 

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