Dimethyl ethylene

The dithionitronium cation SNS+ (as the AsFg salt) underwent quantitative concerted symmetry-allowed cycloaddition reactions with alkenes (ethylene, methylethylene, trans- and +r-l,2-dimethylethylene, 1,1-dimethyl-ethylene, tetramethylethylene, and norbornene) to give 1,3,2-dithiazolidine cations 76 (Equation 20) <1996JCD1997>. 

The V02+ complex of the ligand NN -bis(salicylidene)-l,l-(dimethyl)ethylene-diamine has ne = 1.76 BM, which is almost temperature invariant there is much evidence that the complex is monomeric with a trigonal-bipyramidal structure.427... 

D-Ribopyranose tetraacetate56 has been used as a derivative for the identification of D-ribose14 and, more recently, Hardegger, Schreier and El Heweihi57 have prepared dimethyl, ethylene and dibenzyl thioacetals (mercaptals) of D-ribose for this purpose. According to Zinner58 the di-n-propyl and diisobutyl thioacetals are particularly suitable derivatives for the identification of ribose. 

Other organic superconductors are based on DMET (dimethyl-ethylene-dithio-diselenedithiafulvalene), an asymmetric molecule hybridized from ET and TMTSF [17]. According to its origin the physical properties are somewhere between one and two dimensional. Also based on asymmetric donors are the ambient-pressure superconductors (MDT-TTF)2Aul2 with Tc 3.5 K [18] and (DMET-TSeF)2A with X = A11I2 and I3 (7[ below 1K), where MDT-TTF stands for methylenedithio-TTF and DMET-TSeF for dimethyl-ethylenedithio-tetraselenafulvalene [19]. 

Thermolysis of 35 at 220 °C in benzene produces the corresponding silylene and 1,2-dimethyl ethylene. In the absence of trapping agents, the only product isolated in 87% yield is l,l-di-/i< r/-butyl-4,4-dimethyl-2-triisopro-pylsilyl-l,2-disiletane (Scheme 8) <2003OM2233>. 

Athene carbonates. Ethylene carbonate (I) is formed when ethylene oxide and carbon dioxide are heated at 100° in benzene solution containing this nickel(0) complex. Under similar conditions, 2-methyl-1,2-epoxypropane is converted into 1,1-dimethyl-ethylene carbonate and 2,3-epoxybutanc into 1,2-dimethylethylene carbonate. Several other catalysts of the type L2Ni(0) are effective. 

The three compounds are known. The one to which the first formula is assigned is called normal butylene the second is isobutylene. In order to make clear the structure of hydrocarbons in this series they are often named as derivatives of ethylene. The butylene which has the structure represented by formula (2) is called unsymmetrical dimethyl-ethylene, and that represented by formula (3), symmetrical dimethylethyleiie. 

Write the graphic formulas of the compound formed as the result of the addition of hydriodic acid and of bromine to the following (a) propylene, (h) isopropyl-ethylene, (c) symmetrical dimethyl-ethylene, and (d) unsymmetrical dimethyl-ethylene. 

Flexible chains, which tend to form a random coil in the isotropic state, are highly incompatible with LCs. Phase equilibrium studies indicate that chain molecules such asn-alkanes [Kronbergetal., 1976 Orendi and Ballauff, 1989], dimethyl ethylene glycol ethers [Abe et al., 1993], poly(oxyethylene) [Dubault et al., 1982], or polystyrene [Ballauff, 1986] are very disruptive to the nematic order and thus only a limited amount is allowed to exist in LCs [Martire, 1979]. 

N,N-dimethyl ethylene urea, N-acetylpyrrolidone, N,N-diethylacetamide, N-ethylpyrrolidone, N,N-dimethylpropioncimide, N,N-dimethylbutyramide, and N,N-dimethylisobutyramide. (Li or Ca chloride can increase the solubility of sparingly soluble rodlike aromatic polyamides such cis PBA in DMAc, TMU, and NMP)... 

Photolysis.—Photochemical transformations of thietan derivatives have not received much attention, but it appears that the initial process is homolysis of a C—S bond, and that extrusion of sulphur is not important, in contrast to the case for thiirans. A reversed [2 + 2]cycloaddition may occur via initial homolysis of the C—S bond, 2,2-diphenyl-3,3-dimethyl-4-isopropylidenethietan, for example, giving l,l-diphenyl-2,2-dimethyl-ethylene, and rra j-2-phenyl-3-benzoylthiiran being converted into a mixture of cis- and /mns-benzalacetophenone, probably by way of its triplet excited state. Thietan vapour on photolysis gave mixtures containing ethylene, propylene, and polymer, and on prolonged irradiation, 2-methylthiiran. ... 

In a similar structure, t-(P-5,5-DMEDT-TTF)2-(AuBr2)i(AuBr2)o75, where P-S jS -DMEDT-TTF is (13a -5, 5 -7f) (a molecule also with a chiral structure), the dimethyl-ethylene group is disordered [383]. The... 

Poly (isobutene) see Poly( 1,1 -dimethyl ethylene) Poly(3-methyl-l-hexene) Fractional solution... 

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