Arsenites allyl—

No thermal Arbuzov rearrangement shown in equation 69 has been found in the reaction of allylic arsenite with Pd(PPh3)4 ... 

The uses of constant-current coulometry for the determination of drugs in biological fluids are few, basically due to sensitivity restriction. Monforte and Purdy [46] have reported an assay for two allylic barbituric acid derivatives, sodium seconal and sodium sandoptal, with electrogenerated bromine as the titrant and biamperometry for endpoint detection. Quantitative bromination required an excess of bromine hence back titration with standard arsenite was performed. The assay required the formation of a protein-free filtrate of serum with tungstic acid, extraction into chloroform, and sample cleanup by back extraction, followed by coulometric titration with electrogenerated bromine. The protein precipitation step resulted in losses of compound due to coprecipitation. The recoveries of sodium seconal and sodium sandoptal carried through the serum assay were approximately 81 and 88%, respectively. Samples in the concentration range 7.5-50 pg/mL serum were analyzed by this procedure. 

Many subsequent investigations - - " including measurements in the presence of arsenite, hydrogen peroxide or allyl alcohol, have led to the same basic rate expression. Bray and Liebhafsky and Skrabal and Schreiner "... 

This lack of rearrangement 69 has been explained by assuming that the arsenite ion, which is produced by oxidative addition, recombines with the w-allyl group by its oxygen atom again instead of by the arsenic atom (equation 70) ... 

C(3j. This indicated that, after forming the 7t-allyl palladium complex, the arsenite ion OAs attacks at both positions and with the same probability and gives the deuterium-scrambled recoupling product according to equation 71. 

Where X is Br or Cl, the free acids may be obtained by acidification of the alkaline solution, but where X is I, the acids must be isolated as salts to avoid reduction of the arsonic acids by HI. Rather than using alkyl halides, alkyl or dialkyl sulfates or alkyl arenesulfonates can be used. Primary alkyl halides react rapidly and smoothly, secondary halides react only slowly, whereas tertiary halides do not give arsonic acids. Allyl halides undergo the Meyer reaction, but vinyl halides do not. Substituted alkyl halides can be used eg, ethylene chlorohydrin gives 2-hydroxyethylarsonic acid [65423-87-2], C2H7As04. Arsinic acids, R sC OH), are also readily prepared by substituting an alkali metal arsonite, RAs(OM)2, for sodium arsenite ... 

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