A novel synthesis of branched high-molecular-weight (C40+) long-chain alkanes.
Many biological and geochemical questions remain concerning the structures, functions, and properties of naturally occurring high-molecular-weight (C40+) alkanes with various mid-chain alkylation patterns. Above C40, these alkanes are exceedingly difficult to separate and purify, and syntheses can be blocked by the low solubility of intermediates. To overcome these problems, a facile three-step synthesis employing the alkylation of 1,3-dithiane with a suitable alpha,omega-dibromoalkane was developed. Bisalkylation of the bis(dithianyl)alkane intermediate with the appropriate 1-bromoalkane and subsequent desulfurization with Raney nickel furnished the desired long-chain alkane. Long-chain alkanes modified at mid-chain and/or symmetrically near the chain termini (or unmodified, i.e., long-chain n-paraffins) are accessible by the selection of appropriate bromoalkanes. Nine mid-chain methylated (C38H78 to C53H108), one symmetrical terminal-chain dimethylated (C40H82), and four linear (C44H90 to C58H118) long-chain alkanes were synthesized by using this approach. High-temperature gas chromatography (HTGC) was found to have important advantages for evaluating the purity of the synthetic high-molecular-weight alkanes.
Lehmler
Hans-Joachim
HJ
Graduate Center for Toxicology, University of Kentucky, Lexington 40536, USA. hjlehm1@uky.edu
Bergosh
Robert G
RG
Meier
Mark S
MS
Carlson
Robert M K
RM
D000473:Alkanes / Q000138:chemical synthesis* / Q000737:chemistry; D000478:Alkylation; D002849:Chromatography, Gas; D007202:Indicators and Reagents; D013455:Sulfur / Q000737:chemistry
D000473:Alkanes; D007202:Indicators and Reagents; D013455:Sulfur