Fuel instability studies: The synthesis of long chain alkyl substituted indoles

The reactions that are responsible for fuel instability are complex and not well understood. GC/MS analysis of many different middle distillate and fu el oils showed that substituted indoles were always present in both the fue l itself and in the sediments formed by these fuels. The alkyl chain length of substitution of indoles found in fuels varies with distillation range. Indoles found in the middle distillate fraction have an average alkyl chain length of one to eight carbons while in fuel oils, the alkyl side chain ca n be up to twelve or fourteen carbons in length. Commercially, only short c hain alkyl substituted indoles are available. This paper presents our resul ts for the synthesis of long alkyl chain substituted indoles to be used for instability studies.