Benzo thiophenes, hydro

Benzo[ ]thiophene normally undergoes electrophilic substitution at the 3-position more rapidly than at the 2-position <1971AHC(13)284>, so both this and formation of the thioester group favor ketonization of 2-hydro-xybenzo[ ]thiophene which occurs 40 times faster than ketonization of 3-hydroxybenzo[ ]thiophene. The rapid rate of ketonization of the thio-ester enol 2-hydroxybenzo[ ]thiophene is also indicated by its 4.4-fold greater rate of ketonization compared to 2-hydroxyindene, which contrasts with what is found with 3-hydroxybenzo[. ]thiophene and 1-hydroxyindene <1986TL3275>. 

The positive identification of the sulfur compounds in crude oils is a difficult problem often complicated by the lack of reference compounds. This difficulty has been overcome by hydrodesulfurization (see Section VIII), which converts the sulfur compounds into known hydrocarbons. Treatment of a petroleum oil fraction with calcium hexammine converts the benzo[6]thiophenes present into aryl mercaptans, which are readily separable from accompanying aromatic hydrocarbons (e.g., naphthalene) and then identified by hydro-... 

ITuedel Cuafts Acylation op Alkyl, Alkoxy, Halo, and Hydro Benzo[6]thiophenes ... 

Reaction of benzo[6]thiophene-2-carboxaldehyde with pyruvic acid yields the keto acid (321), the oxime of which gives a-amino-y-(2-benzo[6]thienyl)butyric acid (322) on catalytic hydrogenation, and j9-(2-benzo[6]thienyl)acrylonitrile on treatment with acetic anhydride the latter yields 8-(2-benzo[6]thienyl)acrylic acid on hydro-... 

The mechanism of hydrodesulfurization of benzo[6]thiophene and its derivatives involves, as a first step, chemisorption of the molecules (through the sulfur atom lone pair of electrons) in a more or less perpendicular fashion to the catalyst surface. Removal of the sulfur is then thought to produce a diradical which, on subsequent hydro-... 

Since hydrobenzo[c]thiophenes are often used as intermediates for the preparation of benzo[c]thiophene and its derivatives, it is convenient to review the chemistry of these compounds first. Hydro-benzo[c]thiophene 2-oxides and 2,2-dioxides are reviewed in Section VI and l,3-dihydrobenzo[c]thiophen-I-one and l,3-dihydrobenzo[c]-thiophen-l,3-dione are covered in Section VII. 

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