The condensation of dodecanal with
meso-erythritol catalyzed by
p-toluenesulfonic acid was investigated for preparing new types of non-ionic surfactants or their intermediates. The structural and geometrical isomers of long chain cyclic monoacetals of
meso-erythritol were obtained as major products. The isomers were isolated by preparative gas chromatography as their diacetates. The stereochemical structures of the isolated three isomers were elucidated spectrometrically. The isomers were identified as
r-2-undecyl-
c-4-acetoxymethyl-
t-5-acetoxy-1, 3-dioxane (1a) in chair form (
e,
e,
e),
trans-2-undecyl-4-(1, 2-diacetoxyethyl)-1, 3-dioxolane (2a), and
cis-2-undecyl-4-(1, 2-diacetoxyethyl)-1, 3-dioxolane (3a).
The β-/α-ring ratio of the resulting monoacetals was in fair agreement with that obtained for glycerol acetals, however, the
cis/
trans ratio of the 1, 3-dioxolanes differed markedly from each other. On the basis of these ratios, steric effects on the formation of
meso-erythritol monoacetals were discussed.
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