Phosphenous acid

Gas phase hydrolysis under special conditions yields unstable phosphenous acid, H0-P=0 (4.209), which can be detected by infrared spectroscopy. 

Esters of phosphenic acid (monometaphosphate esters) (5.329b) are also generally unstable (Chapter 13.1). They can be obtained in some cases from cyclic esters. 

The experimental first-order decay rate for pentachlorobenzene in an aqueous solution containing a nonionic surfactant micelle (Brij 58, a polyoxyethylene cetyl ether) and illuminated by a photoreactor equipped with 253.7-nm monochromatic UV lamp is 1.47 x lO Vsec. The corresponding half-life is 47 sec. Photoproducts reported include all tetra-, tri-, and dichlorobenzenes, chlorobenzene, benzene, phenol, hydrogen, and chloride ions (Chu and Jafvert, 1994). Chemical/Physical. Emits toxic chlorinated acids and phosphene when incinerated (Sittig,... 

PHOSPHORIC ACID, DIEMTHYL ESTER, ESTER WITH METHYL 3-HYDROXYCROTONATE PHOSPHORIC ACID. (1-METHOXYCARBOXYPROPEN-2-YL) DIMETHYL ESTER PHOSPHENE(FRENCH)... 

Suppose we consider some very weakly basic compounds, such as ketimines, phosphines, and oxiranes. A very interesting method of dealing with oxiranes was developed by Durbetaki. The oxirane was reacted with hydro-bromic acid to form the bromohydrln. This type of reaction has long been known using hydrochloric acid, but in that medium the reaction takes approximately three hours. In glacial acetic acid, the reaction is enough to allow you to titrate directly at normal speed. You can get an end point potentiometrically or with an indicator. In fact, if you have a mixture of amine and oxirane, you can get two potentlometric breaks, the first for the amine and the second for the oxirane. Amides, phosphene oxides, triphenyl methanol, and amine oxides are very weak bases and cannot be titrated in glacial acetic acid under ordinary conditions. However, they can be titrated if one uses acetic anhydride as solvent, or if one uses a solvent that is mixed with acetic anhydride. Why does acetic anhydride work There are two reasons. First, it removes the last trace of water from the solution secondly, perchloric acid in the presence of acetic anhydride forms the ion CHsCO". Since this is an extremely reactive substance, one can titrate very weak bases. 

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