Six equivalents of a compound containing this element and chlorine are used to convert an aldehyde to an E-alkene in the Takai olefination. E.J. Corey and Bill Suggs discovered a pyridinium salt reagent in which this element 
Six equivalents of a compound containing this element and chlorine are used to convert an aldehyde to an E-alkene in the Takai olefination. E.J. Corey and Bill Suggs discovered a pyridinium salt reagent in which this element is bound to oxygen and chlorine. This metal's trioxide is combined with acetone and sulfuric acid in a reagent which is used to convert primary alcohols to carboxylic acids. This metal, which is used in organic chemistry as part of the PCC and Jones reagents, imparts a red color to corundum. For 10 points, name this metal which is named for its ability to change the color of many metal compounds.
Six equivalents of a compound containing this element and chlorine are used to convert an aldehyde to an E-alkene in the Takai olefination.
chromium [or Cr]