CDT

Pd-cataly2ed reactions of butadiene are different from those catalyzed by other transition metal complexes. Unlike Ni(0) catalysts, neither the well known cyclodimerization nor cyclotrimerization to form COD or CDT[1,2] takes place with Pd(0) catalysts. Pd(0) complexes catalyze two important reactions of conjugated dienes[3,4]. The first type is linear dimerization. The most characteristic and useful reaction of butadiene catalyzed by Pd(0) is dimerization with incorporation of nucleophiles. The bis-rr-allylpalladium complex 3 is believed to be an intermediate of 1,3,7-octatriene (7j and telomers 5 and 6[5,6]. The complex 3 is the resonance form of 2,5-divinylpalladacyclopentane (1) and pallada-3,7-cyclononadiene (2) formed by the oxidative cyclization of butadiene. The second reaction characteristic of Pd is the co-cyclization of butadiene with C = 0 bonds of aldehydes[7-9] and CO jlO] and C = N bonds of Schiff bases[ll] and isocyanate[12] to form the six-membered heterocyclic compounds 9 with two vinyl groups. The cyclization is explained by the insertion of these unsaturated bonds into the complex 1 to generate 8 and its reductive elimination to give 9. 

In the carbonylation of trans,trans,cis-CDT, the trans double bond is attacked preferentially to give the monoester 10, and then the diester 11. Attack of the cis double bond to give the triester is slow[15]. Only the C-16 alkene was carbonylated regio- and stereoselectively to give the Ibo-carboxy-late 12 by carbonylation of the C-5 and C-16 unsaturaied steroid[]6]. 

CDT. canyon diabolo troilite (a standard for sulfur isotopes see VCDT)... 

V. a term used to describe a voltage difference between one electrode and another VCDT. Vienna canyon diabolo troilite (actually silver sulfide used as a replacement standard for CDT [sulfur isotopes])... 

The reaction of a mixture of 1,5,9-cyclododecatriene (CDT), nickel acetylacetonate [3264-82-2], and diethylethoxyalurninum in ether gives red, air-sensitive, needle crystals of (CDT)Ni [12126-69-1] (66). Crystallographic studies indicate that the nickel atom is located in the center of the 12-membered ring of (CDT)Ni (104). The latter reacts readily with 1,5-cyclooctadiene (COD) to yield bis(COD) nickel [1295-35-8] which has yellow crystals and is fairly air stable, mp 142°C (dec) (20). Bis(COD)nickel also can be prepared by the reaction of 1,5-COD, triethylaluminum, and nickel acetylacetonate. 

A WBL can also be formed within the silicone phase but near the surface and caused by insufficiently crosslinked adhesive. This may result from an interference of the cure chemistry by species on the surface of substrate. An example where incompatibility between the substrate and the cure system can exist is the moisture cure condensation system. Acetic acid is released during the cure, and for substrates like concrete, the acid may form water-soluble salts at the interface. These salts create a weak boundary layer that will induce failure on exposure to rain. The CDT of polyolefins illustrates the direct effect of surface pretreatment and subsequent formation of a WBL by degradation of the polymer surface [72,73]. 

Other isomers of cdt are also obtained and, if a coordination site on the nickel is blocked by the addition of a ligand such as a tertiary phosphine, dimerization of the butadiene, rather than trimerization, occurs. 

Dimethyl-l,2,2,3-tetramethyl-A -1,2,5-azasilaboroline with [Fe2(CO)9] gives sandwich 62 and sandwich 63 (82AGE207, 82CB738) with Cp)Co(C2H4)2]. With [Ni(CDT)] or in a vapor phase with metallic nickel, sandwich 64 (M =Ni) is formed. The vapor-phase synthesis with iron gives 64 (M = Fe). In all these sandwiches, 62-64, the j " -coordination of the heterocyclic ligand is realized. 

Hexabromocyclododecane (HBCD) is prepared by the bromination of lZ,5E,9E-cyclododecatriene (CDT). The term "HBCD" will be used here to denote the commercial product containing various isomer compositions. Bromination of CDT leads to three isomers, HBCD-1 (y), HBCD-2 (P) and HBCD-3(a). All three isomers (Fig. 1) were isolated and fully identified (refs. 1,2). 

The Ni sandwich is also obtained when excess ligand is treated with Ni(CDT) (CDT = all-trans-cyclododecatriene) at 70-80 C. The yield of the orange-red sandwich is 78%. 

Lithium-transition metal compounds are formed by reactions of, e.g., Ni CDT ... 

There are fewer examples of sodium-bonded eompounds than of those containing Li. When (CDT)Ni is treated with a salt-free NaPh-LiPh mixture (Na Li = 2-4) in the mole ratio (NaPh + LiPh) Ni = 4 in ether in the presence of C2H4, the complex [(PhNa)2(Et20)2lNi(C2H4) (I) precipitates as an orange-red powder, whereas... 

V-SMOW, Vienna Standard Mean Ocean Water. V-CDT, Vienna Canyon Diablo Troilite. 

The moving harmonic wave t) in equation (1.3) is also known as a plane wave. The quantity kx — CDt) is called the phase. The velocity (o/k is, known as the phase veloeity and henceforth is designated by Uph, so that... 

Isoprene does not participate in the reaction under the above-optimized conditions. The combination of Ni(cdt) and c-Cy3P promotes the reaction. Unfortunately, however, the reaction results in a very complex mixture consisting of 1 1 and 1 2 adducts of acetaldehyde and isoprene. The 1 1 adducts (8a,b) are the minor products (Eq. 2) [12]. Except for 8e, all the products are out of material balance (vide supra, requiring one molecule of H2) and it is difficult to give any mechanistic rationale for their formation. 

---