The spectrophotometric determination of aliphatic hydroxyl in esters with vanadium oxinate

✍ Scribed by R. Amos

• Book ID: 104100852
• Publisher: Elsevier Science
• Year: 1968
• Tongue: English
• Weight: 899 KB
• Volume: 40
• Category: Article
• ISSN: 0003-2670
• DOI: 10.1016/s0003-2670(00)86754-9

✦ Synopsis

Durin~esterification studies of fumaxic acid by even-carbon-numbered straightchain aliphatic alcohols covering the range octanot to octadecanol, the concentration of unrcacted alcohols had to be measured. These were usually present in the concentration range o.og-2.0 wt.% in the finishecl ester. Althouf$ the normal acylationg procedures were perfectly satisfactory at the higher levels of alcohol concentration, the precision deteriorated as the atcohal concentrations fell below I .o wt.Oio, and a more sensitive spectrophotometric method was therefore sought. The first spectrophotometric method to be considered was that of JOHNSON AND CIZITCHFIDLD~ wtto described a rapid and simple procedure for the determination of hydroxyl groups in primary and secondary alcohols. The method is based on the reaction of hydroxyl with 3,S-dinitrobcnzoyl chloride in the presence of pyridine. After the reaction has been completed the pyridine is neutralised with hydrochloric acid and the dinitrobenxoatc ester is extracted into hexane. Treatment of the hexane