Dimethyl phosphite

Structural formula
General
Surname	Dimethyl phosphite
other names	Dimethyl phosphonate DMP Phosphorous acid dimethyl ester Dimethyl hydrogen phosphite Dimethyl hydrogen phosphonate Phosphonic acid dimethyl ester
Molecular formula	C 2 H 7 O 3 P
Brief description	colorless, hardly inflammable liquid with a faint odor
External identifiers / databases
CAS number 868-85-9 EC number 212-783-8 ECHA InfoCard 100.011.622 PubChem 13361 ChemSpider 10415644 Wikidata Q1225746
properties
Molar mass	110.05 g mol −1
Physical state	liquid
density	1.19 g cm −3
Melting point	<−60 ° C
boiling point	171-172 ° C
Vapor pressure	1.5 h Pa (20 ° C)
solubility	Hydrolysis in water
Refractive index	1.4036
safety instructions
GHS labeling of hazardous substances Caution H and P phrases H: 317-341-351-412 P: 273-280
Toxicological data	~ 3000 mg kg −1 ( LD 50 ,  rat ,  oral )
As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions . Refractive index: Na-D line , 20 ° C

Dimethyl phosphite is a chemical compound from the group of phosphorous acid esters . It is in the form of a colorless and hardly inflammable liquid.

Extraction and presentation

Dimethyl phosphite is produced in closed systems by the reaction of phosphorus trichloride with methanol or sodium methoxide .

${\displaystyle \mathrm {PCl_{3}+3\ CH_{3}OH\longrightarrow (CH_{3}O)_{2}P(O)H+CH_{3}Cl+2\ HCl} }$

In 2002 the global production volume was between three and fifteen thousand tons per year, one third of which was manufactured by Bayer AG in Europe.

properties

Dimethyl phosphite is soluble in water with hydrolysis . The aqueous solution reacts strongly acidic. When heated above 220 ° C, it decomposes to form phosphorus oxides. Dimethyl phosphite has a viscosity of 1.4 mPa · s and a surface tension of 37.6 mN / m at 20 ° C.

Its vapors can form an explosive mixture with air when heated above the flash point (70 ° C).

use

Dimethyl phosphite is used as an intermediate in the manufacture of various chemical compounds. So z. B. for oxo compounds and for the addition of alkenes , which in turn are used, among other things, as corrosion inhibitors , pesticides and pharmaceuticals and flame retardants .

Risk assessment

Dimethyl phosphite is classified as carcinogenic in category 3b (substances which give cause for concern because of their proven / possible carcinogenic effect).

Dimethyl phosphite is one of the chemical substances that are produced in large quantities (“ High Production Volume Chemical ”, HPVC) and for which the Organization for Economic Cooperation and Development (OECD) collects data on possible hazards (“ Screening Information Dataset ”, SIDS ) was made.

In 2012, dimethyl phosphite was included by the EU in the Community's ongoing action plan ( CoRAP ) in accordance with Regulation (EC) No. 1907/2006 (REACH) as part of substance evaluation . The effects of the substance on human health and the environment are re-evaluated and, if necessary, follow-up measures are initiated. Dimethyl phosphite uptake was caused by concerns about its classification as a CMR substance, consumer use , high (aggregated) tonnage, high risk characterization ratio (RCR) and widespread use. The re-evaluation took place from 2012 and was carried out by the Netherlands . A final report was then published.

Individual evidence

1. ↑ ^{a b c d e f g h} Entry on dimethyl phosphite in the GESTIS substance database of the IFA , accessed on January 9, 2019(JavaScript required) .
2. ↑ Entry on Dimethyl Hydrogen Phosphite in the Hazardous Substances Data Bank , accessed on November 18, 2014.
3. ↑ ^{a b c d e} OECD : Screening Information Dataset (SIDS) Initial Assessment Report (SIAR) for Dimethyl phosphonate , accessed on November 4, 2014.
4. ↑ European Chemicals Agency (ECHA): Substance Evaluation Conclusion and Evaluation Report .
5. ↑ Community rolling action plan ( CoRAP ) of the European Chemicals Agency (ECHA): Dimethyl phosphonate , accessed on March 26, 2019.