Zinc chloride is a common reagent in the laboratory useful Lewis acid in organic chemistry.
Molten zinc chloride catalyses the conversion of methanol to hexamethylbenzene:
Other examples include catalyzing (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 hydrated  sample shown in the picture above.
Zinc chloride also activates benzylic and allylic halides towards substitution by weak nucleophiles such as alkenes:
In similar fashion,  promotes selective sodium cyanoborohydride| 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 catalyzed 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 , provide control of stereochemistry in aldol condensation reactions due to chelation on to the zinc. In the example shown below, the threo product was favored over the erythro by a factor of 5:1 when  in DME/ether was used. The chelate is more stable when the bulky phenyl group is pseudo-equatorial rather than pseudo-axial, i.e., threo rather than erythro.