Arsonates pyrolysis

It has already been noted that the esters of arsinous and arsonous acids disproportionate of heating. The formation of As(OR)3 in the pyrolysis of arsonic acid derivatives is thought to be the product of the secondary disproportionation reaction of the primary product RAs(OR)2-... 

Arsonic acid ester Pyrolysis temperature (°C) Pyrolysis product Reference... 

The pyrolysis of organoarsenic compounds containing the arsenyl moiety has some limited preparative applications [arsenyl (As=0) by analogy with phosphoryl (P=0)]. The compounds are based on the arsonic acid RAs(0)(0H)2, the arsinic acid R2As(0)0H and the arsine oxide R3As=0 structures. The acids are in interesting contrast with the phosphorus series. The phosphonic and phosphinic esters are prepared from the phosphorus(III) precursors via the Arbuzov synthesis. This synthetic route fails with the arsenic analogues, and further, if an alkyl halide or a salt is added in the pyrolysis of arsonic or arsinic acid esters a retro-Arbuzov reaction takes place . ... 

The pyrolysis of arsonic acid esters results in low yields of arsenic(III) esters. 

Jack Hubball is a lead criminalist with the Connecticut State Police Forensic Laboratory. The Chemistry Section of the laboratory provides analyses for organic compounds from a variety of samples submitted from crime scenes. However, the majority of samples are from suspect-arson fire scenes. Many of these samples contain pyrolysis products and/or polymer additives. During his tenure at the Forensic Laboratory, Dr. Hubball has analyzed more than 10,000 items. In addition to his duties as an analyst, he is the quality manager for the Forensic Laboratory and is responsible for most aspects of the lab QA/QC program. He is the laboratory representative to the Connecticut State Police K-9 Unit and provides final testing and third party certification for the accelerant, drug and explosives detection teams. 

Heat transfer to the substrate has interesting effects on fire behavior and arson investigation. As shown in Figure 9.16 (top frame), heat may reach deep into a substrate such as wood even when oxygen cannot. The result is pyrolysis ("fire cutting") or decomposition in a reducing environment. We discussed pyrolysis in Section 5.5.2 in the context of an inlet to a gas chromatograph, and the same principles apply here. The products of p)uolysis are different from those of... 

Debris recovered from the fire scene is often wet and burned, and may consist of material such as wood, carpet, carpet padding, tile, and other synthetic materials, all of which can contribute interfering volatile pyrolysis products that can make the identification of the accelerants difficult. The loss of accelerants through adsorption into the debris, evaporation from the heat of the blaze, and the presence of water all contribute to make the identification of accelerants a challenging task. GC can be a powerful tool in the analysis to separate and identify the accelerant in the presence of these interferences. Fultz and DeHaan have written an excellent chapter on GC in arson and explosive analysis (156). 

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