SYNTHESIS AND CHARACTERIZATION OF SELECTIVELY FLUORINATED STEARIC ACIDS (OCTADECANOIC ACIDS) AND THEIR TRISTEARINS - THE EFFECT OF INTRODUCING ONE AND 2 FLUORINE-ATOMS INTO A HYDROCARBON CHAIN
L. Dasaradhi et al., SYNTHESIS AND CHARACTERIZATION OF SELECTIVELY FLUORINATED STEARIC ACIDS (OCTADECANOIC ACIDS) AND THEIR TRISTEARINS - THE EFFECT OF INTRODUCING ONE AND 2 FLUORINE-ATOMS INTO A HYDROCARBON CHAIN, Perkin transactions. 2, (2), 1995, pp. 221-225
The synthesis and physical properties of 2,2',2''- and 12,12',12''-tri
flubrotristearins 2 and 3 and 12,12,12',12',12'',12''-hexafluorotriste
arin 4 are described. NMR, X-ray powder diffraction, melting point and
differential scanning calorimetry analyses of these compounds are rep
orted and comparisons are drawn with tristearin 1. Analysis of Langmui
r film isotherms of the stearic acids gave the average area occupied b
y each molecule in a condensed monolayer and was used as a method to p
robe disorder in the hydrocarbon chains. Of the compounds studied, 3 p
ossesses the closest behaviour to tristearin. The incorporation of a C
F2 group into the lipid chain in 4 imparts unique physical properties
to the tristearin and a novel thermodynamically stable polymorphic for
m (beta'') is observed. This is attributed to a conformational change
in the hydrocarbon chain induced by the CF2 groups. Langmuir film anal
ysis of the selectively fluorinated stearic acids (octadecanoic acids)
7 and 8 reinforce this conclusion.