Solid-state reactivity butadienes

The solid state reactivity of butadiene derivatives has first been investigated by G.N.J. Schmidt and coworkers (1-1). They observed for a number of 1,4-disubstituted compounds that exposure to UV light leads to the formation of dimers according to a (2 2]-cycloaddition reaction. The structure of the dimers was found to be strictly related to the monomer arrangement in the crystal lattice. Oligomers or polymers could only be obtained as side products. 

Modes of Adsorption of Sulfur-Containing Compounds. In typical gas oil, more than 70 different sulfur species can be detected by using gas chromatography-mass spectroscopy techniques. Moreover, the major components are alkylbenzothiophenes and alkyldibenzothiophenes. Consequently and to simplify studies already intrinsically complex, an impressive amovmt of studies were devoted to the HDS reactivity of the family of thiophene compovmds ((thiophene, BT, or DBT). The first step of any of these studies concerning the thiophene HDS mechanism is to describe the elemental steps of this process. The most general mechanism accepted in a solid-state point of view is to consider the HDS reaction as a four-electron reduction process releasing H2S and butadiene from thiophene (148). 

The reactivity of butadiene and -diyne derivatives in layer perovskites demonstrates the suitability of these complex salts to act as templates for solid state reactions. Besides the polyaddition also other chemical reactions should be able to occur with a high stereoselectivity, as for example isomerizations, or addition reactions, such as hydrations, halogenations, oxidations, or polycondensations. In any case it will... 

Klin dig s cationic iron(II) complex 39a, derived from tra s-l,2-cyclopentanedi-ol, is a stable, isolable brown solid that possesses sufficient Lewis acidity to catalyze Diels-Alder reactions between unsaturated aldehydes and dienes [95]. The highest selectivities and yields were realized using bromoacrolein as the dienophile (Scheme 32). Further inspection reveals that dienes less reactive than cy-clopentadiene give cycloadducts in higher yield and enantioselectivity, a characteristic that is even more impressive when one considers that the endo and exo transition states produce enantiomeric products for isoprene and 2,3-dimethyl-butadiene. Cyclohexadiene may be used in the reaction with bromoacrolein to afford the cycloadduct in 80% de and >99% ee. In the case of cyclopentadiene. 

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