Potassium bisulfate catalyst

The practical method of preparing cyclohexene is the dehydration of cyclohexanol. Many reagents have been used for this purpose. The following is a partial list potassium bisulfate,1 oxalic acid,2 sulfuric acid,3 />-toluene sulfonic acid,4 and iodine.5 In addition, cyclohexanol has been dehydrated at high temperatures over various catalysts.6... 

Dehydration. Pyruvic acid was prepared by Berzelius in 1835 by destructive distillation of tartaric acid or glyceric acid, but the process is improved by use of potassium bisulfate as dehydration catalyst. Thus a mixture of 2.7 moles of tartaric... 

Acid salts, such as potassium bisulfate, and salts of strong acids with weak bases have been tried as catalysts, but any activity they have may be attributed to the hydrogen ions present in their solutions. The presence of zinc chloride seetns to enhance the catal3dic effect of acids. The addition of a large amount of calcium chloride aids in the separation of water as a layer. Zinc and tin chlorides are said to be active catalysts. ... 

In this oxidation, tetrabutylammonium bisulfate works as a phase transfer catalyst in a two phase system, consisting of water and dichloromethane, in which chromic acid is formed by the action of sulfuric acid on potassium dichromate. 

Aldehydes. Primary alcohols (in CH2CI2) can be oxidized to aldehydes with potassium dichromate in 9 A/ sulfuric acid in the presence of tetra-n-butylr ammonium bisulfate as a phase-transfer catalyst. It is generally advantageous to use a slight excess of oxidant. The oxidation is complete in a few seconds at room temperature. Yields are generally high except for water-soluble aliphatic alcohols and ,/3-unsaturated alcohols (the double bonds appear to be oxidized). Of course, secondary alcohols can also be oxidized to ketones in the same way. ... 

---