2-Ethyl-3-methylthiophene

At a concentration of 2ppm it has a fruity, slightly milky and floral note (Chemisis, 1981, 1993). (J.6) Thiophene, 4-ethyl-2-methyl-, 4-ethyl-2-methylthiophene [13678-54-1]... 

This activation of the ortho position is most strikingly illustrated in the reactivity of 2,5-dimethylthiophene, which competitive experiments have shown to undergo the SnCb-catalyzed Friedel-Crafts reaction more rapidly than thiophene and even 2-methylthiophene. The influence of the reagent on the isomer distribution is evident from the fact that 2-methoxythiophene is formylated and bromi-nated (with A -bromosuccinimide) only in the 5-position. Similarly, although 3-bromo-2-methylthiophene has been detected in the bromi-nation of 2-methylthiophene with bromine, only the 5-isomer (besides some side-chain bromination) is obtained in the bromination of alkylthiophenes with A -bromosuccinimide. ° However, the mechanism of the latter type of bromination is not established. No lines attributable to 2-methyl-3-thiocyanothiophene or 2-methyl-3-chIoro-thiophene could be detected in the NMR spectra of the substitution products (5-isomers) obtained upon thiocyanation with thiocyanogen or chlorination with sulfuryl chloride. 2-Methyl- and 2-ethyl-thiophene give, somewhat unexpectedly, upon alkylation with t-butyl chloride in the presence of Feds, only 5-t-butyl monosubstituted and... 

Wild and cultivated blackberries have been used as food and medicine for hundreds of years [106]. Approximately 150 volatiles have been reported from blackberries [107]. The aroma profile is complex, as no single volatile is described as characteristic for blackberry [108, 109]. Several compounds have been suggested as prominent volatiles in blackberries using AEDA, e.g. ethyl hexanoate, ethyl 2-methylbutanoate, ethyl 2-methylpropanoate, 2-heptanone, 2-undecanone, 2-heptanol, 2-methylbutanal, 3-methylbutanal, hexanal, ( )-2-hexenal, furaneol, thiophene, dimethyl sulfide, dimethyl disulfide, dimethyl trisulfide, 2-methylthiophene, methional, a-pinene, limonene, linalool, sabinene. 

Shibamoto and Russell (46) heated an aqueous glucose-ammonia-hydrogen sulfide solution at 100° for two hours. Of the 34 major com- ponents identified, 2-methylthiophene accounted for 24.9% of the area of the chromatographic peaks ethyl sulfide, thiophene, furfural, and 2-acetylfuran each accounted for 10-11%, and methyl sulfide and 2,5-di-methylthiophene, 7% each. The reaction mixture as a whole was deemed by sensory panel evaluation to have a cooked beef odor. 

Tlie regioselectivity of the reaction of unsynunetrical diene addends to various fulvene systems has also been explored in some detail. Heating 2-ethyl-5-methylthiophene dioxide in the presence of 6-di-... 

C5H6S 3-methylthiophene 616-44-4 7.740E+09 58.350 5845 C5H120 ethyl propyl ether 628-32-0 8.890E-I-09 61.730... 

Procedure. The sodium amalgam is prepared as described above (see Preparation of Sodium Amalgam Sand of 2-thiophenccarboxylic acid), blanketed with 200 ml. of ether, and the 3-methylthiophene is added. Ethyl chloride is condensed from a cylinder into a tared flask cooled in an ice bath, poured into 4(X) ml. of ice cold ether, and added rapidly to the reaction flask maintained at 10-20°. The mixture is stirred for two hours at room temperature. Carbonation is then carried out as described above under 2-thiophenecarboxylic acid and the product is purified in the same manner (one-half the amount of water and acid being required). The white crystalline needles melt at 119-121°. 

Bromomercuri-2 -methylthiophene.—To prepare this substance mercury 5 5 -dimethyl-2 2 -dithienyl (1-97 grams) and 1 8 grams of mercuric bromide in 100 c.c. of acetone are rapidly brought to the boil, then cooled in ice. The bromide is precipitated by the addition of water. Yield 3-5 grams. It crystallises from ethyl acetate in shining, white needles, melting at 179° to 180° C., and ha dng the usual solubilities. 

Iodomercuri-2-methylthiophene, prepared in a similar manner to the bromide, crystallises from alcohol in silvery needles melting at 111° to 112° C. It is readily soluble in cold ethyl acetate or benzene, less so in acetone unless heated. 

Reactions at Benzylic Positions. - The catalytic oxidation, using a cobalt bromide catalyst, of 2,5-dimethylthiophen to the dialdehydeof 3-methyl-2-ethylthiophen to 2-acetyl-3-methylthiophen and l-(3-methyl-2-thienyl)-ethyl acetate, of the four isomeric methyl acetothienones to the corresponding acetylthiophencarboxylic acids, and of 2-acetoxymethylthio-phen to thiophen-2-carboxylic acid has been reported. The Wittig reaction between 2- and 3-thenyltriphenylphosphonium salts and crocetin dialdehyde has been used for the synthesis of carotenoid analogues with terminal thiophen rings. ... 

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