Zinc compounds synthesis

The ligand 2,5-bis(2-pyridyl)pyrazine was used in the synthesis of a range of zinc compounds to contrast with copper coordination polymers prepared with this ligand.169 Three zinc compounds were structurally characterized, [ZnCl2L(DMF)], [Zn3(OAc)6L2], and [Zn3Cl6L3] respectively a distorted square planar monomer, a linear trimer, and a triangular arrangement of zinc centers. 

The presence of triethylenetetramine in the hydrothermal synthesis of open-framework zinc phosphates results in a number of frameworks with one- to three-dimensional structures. The structures include one-dimensional ladders, two-dimensional layer structures, and one structure where the tetramine is bound to the zinc center. The structural type was highly sensitive to the relative concentration of the amine and phosphoric acid.411 Piperazine and 2-methylpiperazine can be used as templating molecules in solvothermal syntheses of zinc phosphates. The crystallization processes of the zinc compounds were investigated by real time in situ measurements of synchrotron X-ray powder diffraction patterns.412... 

The report of the first zinc compound with a Zn-Zn core elicited a number of critical comments on the structure and bonding of decamethyldizincocene, and the interpretation of the results.236,237 None of the authors of these commentaries questioned the data or their interpretation. Parkin, however, has pointed out that the formal oxidation state of +1 for zinc in this compound is merely due to the convention that metals are assigned an oxidation state of 0 when they form bonds with like atoms.237 If the conventional definition of valence, namely the capacity of atoms to form bonds to other atoms is used, then the zinc atoms in decamethyldizincocene are not monovalent, but divalent. The synthesis of a paramagnetic organozinc compound in which zinc uses only one of its two 4s electrons will remain an interesting challenge to many synthetic organometallic chemists. 

Group 4, surface chemistry on oxides, 12, 515 Group 5, surface chemistry on oxides, 12, 524 molybdenum, surface chemistry on oxides, 12, 529 into nickel complexes, 8, 59-60 with palladium, GO insertion, 8, 200 tungsten, surface chemistry on oxides, 12, 531 on zinc compounds, 2, 366 Alkoxido-imido tungsten complexes structure and properties, 5, 754—755 synthesis, 5, 750/... 

Boron-sulfur bonds, addition, to alkynes, 10, 778 Boron trihalides, in boron compound synthesis, 9, 146 Boron-zinc exchange and copper-catalyzed substitutions, 9, 518 for organozinc halide preparation, 9, 89 Borostannylation, enynes, 10, 334... 

The same reaction was observed in tin chemistry (equation 121)4b and applied also to the synthesis of a tin-zinc compound (equation 122)4b. 

Many studies on the direct reaction of methyl chloride with silicon-copper contact mass and other metal promoters added to the silicon-copper contact mass have focused on the reaction mechanisms.7,8 The reaction rate and the selectivity for dimethyldichlorosilane in this direct synthesis are influenced by metal additives, known as promoters, in low concentration. Aluminum, antimony, arsenic, bismuth, mercury, phosphorus, phosphine compounds34 and their metal complexes,35,36 Zinc,37 39 tin38-40 etc. are known to have beneficial effects as promoters for dimethyldichlorosilane formation.7,8 Promoters are not themselves good catalysts for the direct reaction at temperatures < 350 °C,6,8 but require the presence of copper to be effective. When zinc metal or zinc compounds (0.03-0.75 wt%) were added to silicon-copper contact mass, the reaction rate was potentiated and the selectivity of dimethyldichlorosilane was enhanced further.34 These materials are described as structural promoters because they alter the surface enrichment of silicon, increase the electron density of the surface of the catalyst modify the crystal structure of the copper-silicon solid phase, and affect the absorption of methyl chloride on the catalyst surface and the activation energy for the formation of dimethyldichlorosilane.38,39 Cadmium is also a structural promoter for this reaction, but cadmium presents serious toxicity problems in industrial use on a large scale.41,42 Other metals such as arsenic, mercury, etc. are also restricted because of such toxicity problems. In the direct reaction of methyl chloride, tin in... 

In Volume V of this series, syntheses were presented for coordination compounds of 2,2 -iminodipyridine [di-2-pyridylamine, NH(C6H4N)2] with copper(II) and cobalt-(II). Nickel(II) has also been shown to coordinate with this ligand. A similar behavior is exhibited by zinc salts, which form 1 1 derivatives if a 1 1 mol ratio of reactants is used. The specific choice of a solvent medium for synthesis is dictated by the solubility of the zinc compound. Either acetone or methanol may be used with zinc chloride, methanol with zinc acetate, and pyridine with zinc cyanide. 

The reaction of zinc-copper reagents with acid chlorides has a remarkable generality [7,19] and has found many applications in synthesis (Scheme 9-30) [16,59-64]. The treatment of silyl-protected o-aminated benzylic zinc-copper derivatives such as 33 with an acid chloride leads to a 2-substituted indole 34. Aromatic and heterocyclic zinc compounds provide polyfunctional aromatic or heterocyclic ketones like 35 (see Section 9.6.8 Scheme 9-31) [60]. 

As mentioned in Section 4.2, zinc couples such as zinc-copper and zinc-silver couples have frequently been used in organic synthesis due to their increased reactivity. Their use in the preparation of dialkyl zinc compounds has already been pointed out. To try to summarize all the reactions in which the use of zinc couples has been reported, even for just the past few years, would be much to ambitious for this review. Therefore, we shall just present some representative examples and key papers reporting the latest advances in new types of couples. 

Organomercury and -zinc compounds, R2Hg, R2Zn, are no longer of interest for the syntheses of RBXj or RjBX . In some cases, however, there are organomercurials accessible from which organoboron chlorides can be prepared as shown in the synthesis of 9-borafluorenes ... 

The reaction between PET and DEG takes place at higher temperatures, around 200-230 °C, without catalysts or better still in the presence of the usual catalysts for polyester synthesis (lead, manganese, tin, titanium or zinc compounds). In the situation of transesterification without catalyst, the catalyst existing in PET wastes acts as the catalyst for glycolysis, but the reaction needs longer times. The time for liquefaction of PET with DEG varies from 6-14 hours [2, 4]. 

Schneider E and Price CA (1962) Effect of Zinc compound on synthesis of nucleic acids. Biochim Biophys Acta 55 404-414. 

A synthesis of dienediynes from 2-(hydroxymethylene)cyclopentanone involves the di-enol ditriflate [bis(trifluoromethanesulphonate)] 120, which reacts with an alkyne in the presence of a palladium catalyst to give 121, accompanied by only small amounts of the regioisomer 122. The major product on treatment with the same or different alkyne yields the dienediyne 123 2-(Alkyn-l-yl)-l-methylpyrrolidines 125 (R = Me, pentyl, MesSi or Ph) have been obtained from the thiolactam 124 by sequential alkylation, treatment with a lithium acetylide and reduction with LAH. The phenylthio group in a-(phenylthio)-lactams is displaced by an alkynyl group by the action of an alkyn-l-ylzinc chloride or of di(alkyn-l-yl)zinc compounds. Thus the j -lactam 126 gave 127 and the azaprostacyclin II 128 gave 129 1... 

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