Dicarbon, bonding

Figure 5.9 Potential-energy curves of integral-order dicarbon bonds, calculated by the Heitler-London method for screened nuclei, superimposed on the point-charge covalency curve.

Dicarbadodecaborane, preparation and structure of, 5 342-343 Dicarbomethoxy acetylene, 45 48, 49 Dicarbon decaboranes, 26 85 base degradation, 26 90 bonding, 26 62 dianions, 26 78-79 reaction with Lewis bases, 26 85 1,2-Dicarbonic acid dichlorides, 33 300 Dicarbon nonaborane anion, oxidative coupling, 26 73... 

We close this section relating double bonds and cyclopropanes with dicarbon and its formal cyclopropanated analogs cyclopropyne (44), A 3-bicyclo[1.1.0]butene (45) and [1.1. ljpropellane (46). That is, we consider the series of compounds C2, C2(CH2), C2(CH2)2 and C3(CH2)j. Admittedly, C2 is not a hydrocarbon and somehow does not really belong in the current series, but analysis making use of its inclusion in its reasoning is conceptually no worse than... 

Dicarbonate 14 was used as the starting material to achieve both cis-and trans- ring rearrangement precursors 15 and 16. ROM-RCM of the five-membered carbocycles 15 and 16 leads to 17 and 18. These compounds contain a terminal double bond at position 9, which can be easily functionalised and are set up to form the tricyclic tetraponerines. 

The desymmetrization of dicarbonate 206 was initiated by the addition of one equivalent of N-(3-butenyl) nosylamide 207 under palladium catalysis in the presence of Trost s chiral diphosphine ligand 205. When the first allylic substitution was completed, the reaction was warmed and the resulting intermediate 208 was treated in situ with one equivalent of a second nosylamide 209. Product 210 resulting from this double substitution reaction was submitted to a tandem intramolecular ROM/RCM to furnish key precursor 211, which was engaged in the final cyc-lization step by the reduction of the double bonds, followed by the HCl-promoted domino deprotection of the acetal and aminal formation. 

You will recall that one pair of electrons shared between two atoms constitutes a single chemical bond this is Tewis original definition of the covalent bond. In C2 there are two paris of electron in the pi bonding orbitals, so we have what dicarbon... 

A new synthetic substrate (l,2 0-dilauryl-rac-glycero-3-glutaric acid-(4-methyl-resorufin)-ester), consisting of two glycerol ether and one ester bonds, has been proposed. LPS hydrolyze the latter bond in an alkaline medium to an unstable dicarbonic acid ester that spontaneously hydrolyzes to yield glutaric acid and methylresorufin this is a bluish-purple chromophore with peak absorption at 580 nm. 

In the photoinitiated polymerisation of Jl-vinylpyrrolidinone and N-vinylcaprolactam in dioxane and ethanol, the rate was higher in the latter solvent and monomerlO. This was attributed to the influence of the two additional methylene groups in the caprolactam ring which increases monomer reactivity. Other interesting effects have included the radiation dose on the photopolymerisation of diallyl oxydiethylene dicarbonate O. Here long lived radicals were produced which continue to react in the dark. The rate appears to fit a relaxation model that considers double bonds as traps with increasing lifetimes that are able to transfer to radical sites. 

Cassaday (1950), Shostakovski et al. (1951) and Melnikov et al. (1952) investigated extensively the addition reactions of dialkyl phosphorodithioic acids to unsaturated dicarbonic acid esters, and found that the dialkyl phosphorodithioic acids are added at the double bond in the same way as are mercaptans. This reaction was used by Cassaday (1950) who prepared 0,0-dimethyl-S-(l,2-dicarbethoxy)-ethyl phosphorodithioate by the addition reaction of dimethyl phosphorodithioic acid and maleic acid diethyl ester. This compound, known by the name malathion (89), became one of the most important phosphorus ester insecticides because of its low toxicity to warm-blooded animals. 

Dudis, D. S. Corbett, J. D. (1987). Two Scandium Iodide Carbides Containing Dicarbon Units Within Scandium Clusters - Scgl C2 and Sc4lgC2. Synthesis, Structure and the Bonding of Dicarbon, Inorg. Chem. 26, 1933-1940. 

The unsaturated double bonds in limonene can be epoxidized (11). Carbon dioxide and limonene oxide can be used to get a cyclic limonene dicarbonate. The reaction is shown in Figure 6.4. This compound is useful to produce linear polycarbonates, or poly(ur-ethane)s (PU)s. 

Furthermore, in 1998 Ube Industries, Ltd. expanded their research from doublebond compounds to triple-bond compounds and discovered that alkyne compounds such as methyl propargyl carbonate (13), propargyl acetate (14), and 2-butyne-l,4-diol dimethyl dicarbonate (15) suppress the decomposition of PC [53]. In 1999, the same company discovered that a mixture of methyl propargyl carbonate (13) and VC is capable of improving battery performance even further [27, 54]. 

When it comes to isolated or oligomeric clusters, there is only a limited number of examples. They may all be derived from [R (Z)]X, 2X units (fig. 46). The most oxidized example is Cs2Lu[Lu6(C)]Cli8 with only 9 electrons for mtra-cluster bonding. It forms red transparent crystals. Other quaternary halides with isolated octahedra all with a single carbon atom or the dicarbon unit have 11 to 15 cluster-based electrons (box 8). 

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