Zinc chloride compound with

Trimethylsilyl)-2-propenyl]zinc chloride in four-fold excess, generated in situ from the lithium compound by addition of anhydrous zinc chloride, reacts with chiral ketones, e.g., 2-bor-nanonc, to form the ( )-vinylsilanes with high y-regio- and induced diastcreoselectivity44,45. 

Ferric chloride yields solid solutions with zinc chloride and with lead chloride, but no compounds appear to be formed.5 The existence of the double salt FeCl3.2KF6 has not been confirmed.7... 

A mixture of hydrogen cyanide and hydrogen chloride in the presence of zinc chloride reacts with an aromatic compound to form an aldimine hydrochloride which on hydrolysis produces the corresponding aldehyde. 

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. 

Structurally related bis(dichloromethyl)zinc (prepared from dichloromethyllithium and zinc chloride) gave, with cyclohexene (80°C, benzene), 7-chlorobicyclo[4.1.0]heptane (15%). With the exception of the reactions above, the usefulness of organozinc compounds for the synthesis of chlorocyclopropanes has not been explored. 

Treatment of brominated 3,4-di-O-acetyl-o-xylal with p-nitrophenylhydrazine gave a mixture of the 3,4-di-0-acetyl-2,5-anhydro-D-xylose and -D-xylose p-nitrophenylhydrazones both these compounds and their deacetylated derivatives exhibited a preference for the Ti conformation. Acetylation of L-rhamnose benzoylhydrazone with acetic anhydride and pyridine has been shown to give the a-pyranose derivative (14) rather than the acyclic hydrazone (15) previously claimed (see Vol. 10, p. 74). With acetic anhydride and zinc chloride, compound (14) gave 1,2,3,4-tetra-O-acetyl-a-L-rhamnose, whereas (15) gave the oxadiazoline (16). ... 

C (decomp.). Prepared by reacting ketene with methanol under carefully controlled conditions in the presence of anhydrous zinc chloride. This highly reactive compound has many synthetic uses, chiefly for adding the... 

Carry out this preparation precisely as described for the a-compound, but instead of zinc chloride add 2 5 g. of anhydrous powdered sodium acetate (preparation, p. 116) to the acetic anhydride. When this mixture has been heated on the water-bath for 5 minutes, and the greater part of the acetate has dissolved, add the 5 g. of powdered glucose. After heating for I hour, pour into cold water as before. The viscous oil crystallises more readily than that obtained in the preparation of the a-compound. Filter the solid material at the pump, breaking up any lumps as before, wash thoroughly with water and drain. (Yield of crude product, io o-io 5 g.). Recrystallise from rectified spirit until the pure -pentacetylglucose is obtained as colourless crystals, m.p- 130-131° again two recrystallisations are usually sufficient for this purpose. 

These chlorozincates must not be confused with the non-ionic compounds which quinoline and aniline bases give with neutral zinc chloride the latter have the formulae [(C,H7N)2ZnClt] and [(C,H7N)tZnCl ] respectively, and both are only slightly soluble in water. 

Pure pyridine may be prepared from technical coal-tar pyridine in the following manner. The technical pyridine is first dried over solid sodium hydroxide, distilled through an efficient fractionating column, and the fraction, b.p. 114 116° collected. Four hundred ml. of the redistilled p)rridine are added to a reagent prepared by dissolving 340 g. of anhydrous zinc chloride in a mixture of 210 ml. of concentrated hydrochloric acid and 1 litre of absolute ethyl alcohol. A crystalline precipitate of an addition compound (probable composition 2C5H5N,ZnCl2,HCl ) separates and some heat is evolved. When cold, this is collected by suction filtration and washed with a little absolute ethyl alcohol. The yield is about 680 g. It is recrystaUised from absolute ethyl alcohol to a constant m.p. (151-8°). The base is liberated by the addition of excess of concentrated... 

By interaction of hydrogen cyanide and hydrogen chloride with an anxnatic compound (hydrocarbon, phenol or phenol ether) in the presence of aluminium chloride (or zinc chloride). This is known as the Gattermann... 

The reactivity of 2-methylselenazole toward carbonyl compounds is the same as its thiazoie homolog. Reaction of 2,4-dimethylselenazole with benzaldehyde in the presence of anhydrous zinc chloride as catalyst gives 4-methyl-2-styrylselenazoie [m.p. 74-75 C (19)] (Scheme 43). 

For reaction with hydrogen haUdes, the substitution reaction with haUde ion easily occurs when a cuprous or cupric compound is used as the catalyst (23) and yields a halogenated aHyl compound. With a cuprous compound as the catalyst at 18 °C, the reaction is completed in 6 h. Zinc chloride is also a good catalyst (24), but a by-product, diaHyl ether, is formed. 

Friedel-Crafts reaction of ahyl alcohol with benzene or alkylbenzene yields many kinds of products, in which the reaction species and the product ratio depend on the type of catalyst. Zinc chloride is the most effective catalyst for producing ahyl compounds by this reaction (32). 

Alkyl Isoquinolines. Coal tar contains small amounts of l-methylisoquinoline [1721-93-3] 3-methylisoquinoline [1125-80-0] and 1,3-dimetliylisoquinoline [1721-94-4J. The 1- and 3-methyl groups are more reactive than others in the isoquinoline nucleus and readily oxidize with selenium dioxide to form the corresponding isoquinoline aldehydes (174). These compounds can also be obtained by the hydrolysis of the dihalomethyl group. The 1- and 3-methyhsoquinolines condense with benzaldehyde in the presence of zinc chloride or acetic anhydride to produce 1- and 3-styryhsoquinolines. Radicals formed by decarboxylation of carboxyUc acids react to produce 1-aIkyhsoquinolines. 

Zinc chloride is a Lewis acid catalyst that promotes cellulose esterification. However, because of the large quantities required, this type of catalyst would be uneconomical for commercial use. Other compounds such as titanium alkoxides, eg, tetrabutoxytitanium (80), sulfate salts containing cadmium, aluminum, and ammonium ions (81), sulfamic acid, and ammonium sulfate (82) have been reported as catalysts for cellulose acetate production. In general, they require reaction temperatures above 50°C for complete esterification. Relatively small amounts (<0.5%) of sulfuric acid combined with phosphoric acid (83), sulfonic acids, eg, methanesulfonic, or alkyl phosphites (84) have been reported as good acetylation catalysts, especially at reaction temperatures above 90°C. 

The transmetallation of lithio derivatives with either magnesium bromide or zinc chloride has been employed to increase further their range of synthetic application. While the reaction of l-methyl-2-pyrrolyllithium with iodobenzene in the presence of a palladium catalyst gives only a poor yield (29%) of coupled product, the yield can be dramatically improved (to 96%) by first converting the lithium compound into a magnesium or zinc derivative (Scheme 83) (81TL5319). 

In seawater, HCO3 ions lead to surface films and increased polarization. In aqueous solutions low in salt and with low loading of the anodes, less easily soluble basic zinc chloride [10] and other basic salts of low solubility are formed. In impure waters, phosphates can also be present and can form ZnNH4P04, which is very insoluble [11]. These compounds are only precipitated in a relatively narrow range around pH 7. In weakly acid media due to hydrolysis at the working anode, the solubility increases considerably and the anode remains active, particularly in flowing and salt-rich media. 

A variety of l,2,3,4-tetrahydro-j8-carbolines have been prepared from 3-piperidone phenylhydrazone derivatives. Used initially to obtain pentacyclic derivatives (35) related to the yohimbe alkaloids, this route was later extended to the synthesis of tetracyclic compounds (36). l-Methyl-5,6,7,8-tetrahydro-j8-carboline (37) was prepared in low yield by heating cyclohexanone 2-methyl-3-pyridylhydrazone with zinc chloride, a synthesis probably based on the similar preparation of the tetracyclic compound 38 starting from the corresponding quinolylhydrazine. Abramovitch and Adams extended this approach to the cyclization of cyclohexanone 3-pyri-dylhydrazone (39) itself. The main product was 6,7,8,9-tetrahydro-8-carboline (40), a smaller amount of the j8-isomer (41) also being obtained. This provides a convenient and readily reproducible route to the otherwise difficultly accessible 8-carboline ring system. The favored attack at carbon-2 over carbon-4 of the pyridine nucleus... 

In an effort toward indolo[3,2-h]carbazoles based on Lewis acid-assisted dimerization of benzotriazole derivatives, the necessary starting materials 197 were prepared in good yields from 1-propargylbenzotriazole and 2-iodoaniline followed by alkylation. In the ensuing dimerization step, compounds 197 were treated with zinc chloride in refluxing dichlorometane to afford the indolo[3,2-h]carbazoles 199 or the dihydro derivatives 198 (Scheme 27). Under similar conditions 197, where R = = H, did not undergo dimerization, which suggests that the alkyl... 

A methyl group in the 2-position of the selenazole ring shows the same reactivity as the analogous thiazoles toward carbonyl compounds. By reaction of 2,4-dimethylselenazole with benzaldehyde in the presence of anhydrous zinc chloride catalyst, 4-methyl-2-styryl-selcnazole (9), mp 74-75°C, could be prepared. ... 

The isobomeol so formed melts at 212°, but the determination must be carried out in a sealed tube, as the melting-point is very dose to the temperature of sublimation. It is, however, very rarely that the isobomeol so prepared is free from impurities, and the melting-point will often be found to be as low as 203° to 205°. It is therefore necessary to pare derivatives of the isobomeol in order to identify it with certainty. Kie compound with bromal melts at 71° to 72°. Other compounds will be found mentioned under isobomeol . By dehydration by means of zinc chloride, isobomeol is easily converted into camphene, melting at about 49° to 50°. 

It was noted (23) that the NMR spectrum of compound 32 was identical with that published (34) for the third product (assigned structure 29) isolated from the reaction of tetra-O-acetyl-2-hydroxy-D-glucal with acetic anhydride and zinc chloride. The identity of the compounds was fully established and a revised structure proposed for this third product. In the presence of zinc chloride, therefore, epimerization can occur at an allylic site and the quasi-equatorial C-4 acetoxy group in the erythro isomers 27 and 28 can assume the favored quasi-axial orientation (24). 

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