Zinc chloride complex

There appear to be at least two zinc chloride complexes of pyridine, one of m.p. 207 and composition 2CsH,N,ZnCh, sind the other of m.p. 152° and probable composition 2C,H,N,ZnClt,HCl. The former is slightly soluble in water and in hot ethyl alcohol the latter passes into the former in aqueous solution, is readily soluble in hot absolute ethanol and can therefore be readily recrystaUised from this solvent. 

A number of improvements have been made in these syntheses. For example, the use of ethanoHc ferric chloride and zinc chloride produces a good yield of 2-isopropylquinoline [17507-24-3] from isovaleraldehyde (46). The purification of 2-methylquinoline is facHitated through precipitation. A cmde quinaldine—hydrochloride and zinc chloride complex is prepared and then treated with aqueous base (47). 

The next step in the calculations involves consideration of the allylic alcohol-carbe-noid complexes (Fig. 3.28). The simple alkoxide is represented by RT3. Coordination of this zinc alkoxide with any number of other molecules can be envisioned. The complexation of ZnCl2 to the oxygen of the alkoxide yields RT4. Due to the Lewis acidic nature of the zinc atom, dimerization of the zinc alkoxide cannot be ruled out. Hence, a simplified dimeric structure is represented in RTS. The remaining structures, RT6 and RT7 (Fig. 3.29), represent alternative zinc chloride complexes of RT3 differing from RT4. Analysis of the energetics of the cyclopropanation from each of these encounter complexes should yield information regarding the structure of the methylene transfer transition state. 

The activation energy for the favored transition state TS4 (22.8 kcal mol ) is still somewhat high. Still, the qualitative predictions of enhanced reactivity of the zinc alkoxide-zinc chloride complexes are in full agreement with contemporary ideas about this reaction and represent a major advance in the theoretical understanding of the cyclopropanation process. 

Y Picoline. Commercially pure y-picoline contains )S-picoline and 2 6-lutidine and sometimes traces of non-basic impurities (aromatic hydrocarbons) which cannot be separated by fractionation. The non-basic impurities are removed by steam distillation of the base in dilute hydrochloric or sulphuric acid solution (for details, see under a Picoline). The impure y-picoline is converted into the zinc chloride complexes of the component bases the 2 6-lutidine - ZnClj complex is the least stable and upon steam distillation of the mixture of addition compounds suspended in water, 2 6-lutidine passes over flrst. The complete separation of the 2 6-lutidine may be detected by a determination of the density and the refractive index of the dry recovered base at varioiu stages of the steam distillation. The physical properties are —... 

The zinc chloride complex of l-(2-pyridyl)-2-(2-thienyl)ethyne has been structurally characterized by single crystal X-ray diffraction showing the ligand is a monodentate nitrogen donor. The N2Q2 tetrahedral coordination geometry reveals little apparent influence of the acetylene or thiophene groups.110... 

To avoid coextraction of iron, the iron is initially reduced to its Il-valent state. Then zinc is extracted as a zinc chloride complex into an organic solution containing tributylphosphate (TBP). Zinc is stripped from the organic solution with water or dilute hydrochloric acid (Fig. 14.5). The resulting strip solution is evaporated, either (1) after addition of sulfuric acid, giving a dilute hydrochloric acid condensate and a zinc sulfate precipitate, or (2) directly without any addition, giving a dilute hydrochloric acid condensate and a concentrate zinc chloride product solution. 

Practical interest in high-molecular-weight poly (propylene oxide) centers in its potential use as an elastomer (19). Copolymerization of propylene oxide with allyl glycidyl ether gives a copolymer with double bonds suitable for sulfur vulcanization. Table IV shows the properties of elastomers made with a copolymer prepared with a zinc hexacyano-ferrate-acetone-zinc chloride complex. Also shown are the properties of elastomers made from partially crystalline copolymers prepared with zinc diethyl-water catalyst. Of particular interest are the lower room-... 

Owing to the insolubility of the polar monomer-zinc chloride complex, handling of the reaction mixture is difficult. However, a second patent (73) describes an improved process wherein the polar monomer is utilized in considerable excess with no effect on the polar monomer content of the resulting copolymer, in contrast to the results from a conventional free radical polymerization. This is consistent with the mechanism shown in Reaction 23 and essentially eliminates the participation of a polar monomer-complexed polar monomer complex. 

Hirooka et al. (27, 29) recently reported that an equimolar mixture of acrylonitrile and ethylaluminum dichloride form a complex whose infrared spectrum is similar to that of the acrylonitrile-zinc chloride complex of Imoto et al. (33). The complex is a liquid above 0°C. and... 

As previously discussed, the copolymers produced in the zinc chloride-free radical system are not necessarily random copolymers but are probably the result of the copolymerization of the acrylonitrile-complexed acrylonitrile complex with the olefin-complexed acrylonitrile complex. Further, the olefin-alkylaluminum halide complexed acrylonitrile complex only differs from the olefin—zinc chloride complexed acrylonitrile complex in degree rather than in kind—i.e., the former is an unstable charge transfer complex capable of spontaneous uncoupling of the diradical system followed by intermolecular diradical coupling, while the latter is a stable charge transfer complex requiring radical attack to uncouple the diradical system. 

The Lucas Test The Lucas reagent reacts with primary, secondary, and tertiary alcohols at predictable rates, and these rates can distinguish among the three types of alcohols. When the reagent is first added to the alcohol, the mixture forms a single homogeneous phase The concentrated HC1 solution is very polar, and the polar alcohol-zinc chloride complex dissolves. Once the alcohol has reacted to form the alkyl halide, the relatively nonpolar halide separates into a second phase. (R—OH dissolves, but R—Cl does not.)... 

Hybridization can also help explain the existence and structure of many inorganic molecular ions. Consider, for example, the zinc compounds shown here. At the top is shown the electron configuration of atomic zinc, and just below it, of the divalent zinc ion. Notice that this ion has no electrons at all in its 4-shell. In zinc chloride, shown in the third row, there are two equivalent chlorine atoms bonded to the zinc. The bonding orbitals are of sp character that is, they are hybrids of the 4s and one 4p orbital of the zinc atom. Since these orbitals are empty in the isolated zinc ion, the bonding electrons themselves are all contributed by the chlorine atoms, or rather, the chlor ide ions, for it is these that are the bonded species here. Each chloride ion possesses a complete octet of electrons, and two of these electrons occupy each sp bond orbital in the zinc chloride complex ion. This is an example of a coordinate covalent bond, in which the bonded atom contributes both of the electrons that make up the shared pair. 

Two older direct methods are of limited scope. Tetrafluorohydrazine reacts thermally with alkenes at SO C, 6 h to give a,P-bis(difluoroamino) compounds in good yields.Tetramethyltetrazene-zinc chloride complex, a source of dimethylamino radicals, adds to a-methylstyrene in 30-40% yield.Bar-... 

When EtZnCl is used instead of Et2Zn in these hydrostannolyses with Ph3SnH, and under the same conditions, selective hydrostannolysis of the Zn—C bond occurs to form (triphenyltin)zinc chloride complexes (see Table 1) ... 

Gaizer and Gilbert [Ga 80] found that the stability constants of zinc chloride complexes in DMSO-water solvent mixtures of varying composition are higher than expected from the values measured in pure DMSO and pure water. 

An improved method for the preparation of methyl 4,6-0-benzylidene a- and /3-D-glucopyranoside that can be accomplished within a day utilizes a preformed benzaldehyde-zinc chloride complex. 

The hydrolysis of the zinc chloride complexes was studied(5) by measuring with a glass half-cell h of zinc chloride solutions which were made to contain 5 M Lcn oi-ai by adding NaCl. The [Zn(II)] of the test solutions ranged from 0,01 to 0,2 M,... 

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