Altmetric -. Citations 6. Note: In lieu of an abstract, this is the article's first page. Cited By. This article is cited by 6 publications. The Journal of Organic Chemistry , 85 9 , Morreale,, Kraig A. Wheeler, and, Roman Dembinski. Organic Letters , 9 7 , The effect of ZnCl 2 on green Spanish-style table olive packaging, a presentation style dependent behaviour.
Journal of the Science of Food and Agriculture , 95 8 , Mehrotra , B. Pair your accounts. ZnCl 2 is a mild Lewis acid. Consistent with this character, aqueous solutions of ZnCl 2 have a pH around 4. It is hydrolyzed to an oxychloride when hydrated forms are heated. Such samples may be purified as follows: g of crude ZnCl 2 are heated to reflux in mL anhydrous dioxan in the presence of zinc metal dust.
The mixture is filtered while hot to remove Zn ,and then the filtrate is allowed to cool to give pure ZnCl 2 as a white precipitate. Uses ZnCl 2 is used as a flux for soldering because of its ability when molten to dissolve metal oxides. Typically this flux was prepared by dissolving zinc foil in dilute hydrochloric acid until the liquid ceased to evolve hydrogen, for this reason such flux was known as killed spirits.
This property also leads to its use in the manufacture of magnesia cements for dental fillings and certain mouthwashes as an active ingredient. ZnCl 2 has also been used as a fireproofing agent, for etching metals, and is also a primary ingredient in fabric refresheners such as Febreze.
In the laboratory, zinc chloride finds wide use, principally as a moderate-strength Lewis acid. It can catalyse A the Fischer indole synthesis , and also B Friedel-Crafts acylation reactions involving activated aromatic rings. Related to the latter is the classical preparation of the dye fluorescein from phthalic anhydride and resorcinol, which involves a Friedel-Crafts acylation.
This transformation has in fact been accomplished using even the wet ZnCl 2 sample shown in the picture above. Hydrochloric acid alone reacts poorly with primary alcohols and secondary alcohols, but a combination of HCl with ZnCl 2 known together as the "Lucas reagent" is effective for the preparation of alkyl chlorides.
This reaction probably proceeds via an S N 2 mechanism with primary alcohols but S N 1 pathway with secondary alcohols. Zinc chloride also activates benzylic and allylic halides towards substitution by weak nucleophiles such as alkenes : In similar fashion, ZnCl 2 promotes selective NaBH 3 CN reduction of tertiary, allylic or benzylic halides to the corresponding hydrocarbons. Zinc chloride is also a useful starting reagent for the synthesis of many organozinc reagents, such as those used in the palladium catalysed Negishi coupling with aryl halides or vinyl halides.
In such cases the organozinc compound is usually prepared by transmetallation from an organolithium or a Grignard reagent, for example: Zinc enolates, prepared from alkali metal enolates and ZnCl 2 , provide control of stereochemistry in aldol condensation reactions due to chelation on to the zinc.
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