Di-tert-butyl chromate explained

Di-tert-butyl chromate is an alkoxide with the formula CrO₂(OC(CH₃)₃)₂. It is prepared by treatment of t-butanol with chromic anhydride. It forms red crystals at temperatures below –5 °C, above which it melts to give a red oil.^[1] The complex, which is diamagnetic, is of fundamental interest as a model for the intermediates in oxidations of alcohols by chromium(VI). This complex is stable because as a t-butyl groups lack beta-hydrogens. This complex and its analogues have tetrahedral geometry at chromium, as established by X-ray crystallography of its analogues.^{[2] [3]}

Applications

It is used as a precursor to chromium-based catalysts, such as the Phillips catalyst, which are employed for the polymerization of ethylene.^[4]

Safety

Like other forms of hexavalent chromium, di-tert-butyl chromate is classified as a potential carcinogen by the United States National Institute for Occupational Safety and Health.^[5]

Notes and References

1. 10.1139/v75-438. Esters Chromiques Dérivés d'Alcools Tertiaires. 1975. Richer. Jean-Claude. Hachey. Jean-Marie. Canadian Journal of Chemistry. 53. 20. 3087–3093.
2. 10.1107/S0567740872004261. The crystal structure and absolute configuration of cedryl chromate. 1972. Amirthalingam. V.. Grant. D. F.. Senol. A.. Acta Crystallographica Section B: Structural Crystallography and Crystal Chemistry. 28. 5. 1340–1345.
3. 10.1021/ic00335a009. Chromyl complexes with aryloxy and siloxy ligands. 1990. Stavropoulos. Pericles. Bryson. Nathan. Youinou. Marie Therese. Osborn. John A.. Inorganic Chemistry. 29. 10. 1807–1811.
4. 10.1016/j.jcat.2008.10.015. Influence of porosity on PE molecular weight from the Phillips Cr/Silica catalyst. 2009. McDaniel. M.. Journal of Catalysis. 261. 34–49.
5. Web site: Tert-butyl chromate . International Chemical Safety Cards . NIOSH . July 1, 2014.