Description
2-Methylundecanal has a characteristic fatty odor assuming a floral
note on dilution. It has an acrid, fatty unpleasant flavor at high
levels. At low levels, the flavor is honey- and nut-like. It may be
prepared by cracking the corresponding glycidic acid; from
α-nonyl acrolein; from methyl nonyl ketone and ethyl monochloroacetate
in the presence of sodium ethylate.
Chemical Properties
2-Methylundecanal has a characteristic fatty odor assuming a floral note on dilution. At high levels, it has an acrid, fatty,
unpleasant flavor. At low levels, the flavor is honey and nut-like.
Chemical Properties
clear colourless to yellowish liquid
Occurrence
Reported found in kumquat peel oil.
Preparation
2-Methylundecanal is reported as being
found in nature. It is a colorless liquid, with an odor markedly different from that
of the isomeric dodecanal. It has a fatty odor with incense and ambergris notes.
2-Methylundecanal is produced by two routes:
1) 2-Undecanone is converted into its glycidate by reaction with an alkyl
chloroacetate. Saponification of the glycidate, followed by decarboxylation,
yields 2-methylundecanal.
2) The second synthesis is based on the conversion of undecanal into 2-
methyleneundecanal by reaction with formaldehyde in the presence of
catalytic amounts of amines. Hydrogenation of 2-methyleneundecanal
yields methylnonylacetaldehyde (MNA). A convenient process starts
from 1-decene: hydroformylation gives a mixture consisting mainly of
undecanal and 2-methyldecanal. Reaction of the crude product with
formaldehyde in the presence of dibutylamine yields a mixture containing
over 50% 2-methyleneundecanal. After hydrogenation of the double bond,
pure 2-methylundecanal is separated from the by-products by fractional
distillation.
In comparison with other fatty aldehydes, 2-methylundecanal is used in perfumery
in rather large amounts to impart conifer notes, particularly fir impressions,
but frequently also in fantasy compositions.
Taste threshold values
Taste characteristics at 2 ppm: waxy, fatty, metallic with a citrus nuance.
Flammability and Explosibility
Nonflammable
Synthesis
By cracking the corresponding glycidic acid; from α-nonyl acrolein; from methyl nonyl ketone and ethyl monochloroacetate in the presence of sodium ethylate
Metabolism
See monograph on aldehyde C-8*.
