Trimethylolpropane phosphite explained
Trimethylolpropane phosphite, C2H5C(CH2O)3P, is a phosphite ester used as a ligand in organometallic chemistry. Trimethylolpropane phosphite is sometimes abbreviated to EtCage. It is a white solid that is soluble in organic solvents. It is also highly toxic.[1]
Preparation and reactions
It is prepared by reaction of trimethylolpropane with phosphorus trichloride or by transesterification with trimethylphosphite:[2]
P(OMe)3 + EtC(CH2OH)3 → 3 MeOH + EtC(CH2O)3PThe first member of this series was derived from trimethylolethane,[3] but these derivatives are often poorly soluble. For this reason, the ethyl derivative has received more attention.[4]
Reactions
The compound forms an isolable ozonide, which degrades above 0 °C to release singlet O2.[1]
Coordination chemistry
Several EtCage complexes are known, since the ligand is highly basic (for a phosphite) and has a small ligand cone angle (101°). Illustrative complexes include [(EtCage)<sub>2</sub>Mo(CO)<sub>4</sub>], [Ir<sub>4</sub>(CO)<sub>11</sub>(EtCage)] and (CpMe5)RuCl(EtCage)2, shown below.
Safety
Trimethylolpropane phosphite is very toxic and is a convulsant. LD50 is 1.1 mg per kg bodyweight (mice, i.p.).[5] [6]
References
- Encyclopedia: 4-Ethyl-2,6,7-trioxa-1-phosphabicyclo[2.2.2]octane. Ende. Christopher. Parker. Kathlyn. Kathlyn A. Parker. e-EROS Encyclopedia of Reagents for Organic Synthesis. 2014. 1–3. 10.1002/047084289X.rn01781. 9780470842898.
- Verkade, J. G. "Spectroscopic studies of metal-phosphorus bonding in coordination complexes" Coordination Chemistry Reviews 1972, vol. 9, 1-106.
- Verkade, J. G.; Reynolds, L. T. "The synthesis of a novel ester of phosphorus and of arsenic" Journal of Organic Chemistry (1960), 25, 663-5.
- Huttemann, T. J., Jr.; Foxman, B. M.; Sperati, C. R.; Verkade, J. G. "Transition metal complexes of a constrained phosphite ester. IV. Compounds of cobalt(I), cobalt(III), nickel(II), and nickel(0)" Inorganic Chemistry (1965), 4(7), 950-3.
- Ralf Stöhr et al. Chemische Kampfstoffe und Schutz vor chemischen Kampfstoffen 2. Aufl. Militärverlag der DDR, 1985 (german)
- Structure-toxicity relationships of 1-substituted-4-alkyl-2,6,7-trioxabicyclo[2.2.2.]octanes. Milbrath, Dean S. . Engel, Judith L. . Verkade, John G. . Casida, John E.. Toxicology and Applied Pharmacology. 1979. 47. 2. 287–93. 10.1016/0041-008X(79)90323-5. 452023.
