Zinc Chloride Etherate in Dichloromethane

Abstract

[21512-92-5] C4H10Cl2OZn (MW 210.43) InChI = 1S/C4H10O.2ClH.Zn/c1-3-5-4-2;;;/h3-4H2,1-2H3;2*1H;/q;;;+2/p-2 InChIKey = ZYBFWPARLOUPMV-UHFFFAOYSA-L (Lewis acid catalyst solution that is considerably more active than ZnCl2 in either diethyl ether or dichloromethane) Physical Data: density depends on solvent composition; see Table 1. Table 1. Zinc Chloride–Diethyl Ether Complex Solutions in Dichloromethane Et2O (mL) CH2Cl2 (mL) [Et2O] [ZnCl2] d (g cm−3) Re1. activitya a Activity of solutions observed by dissolving 1 mL of these solutions in 15 mL of CH2Cl2. For details see ref Mayr and Striepe.1 17.0 76.3 1.12 1.33 1460 25.0 69.3 1.64 1.30 305 36.5 58.4 2.40 1.23 41 46.0 49.1 3.00 1.18 18 61.0 33.7 4.02 1.09 3 77.0 18.3 5.06 0.994 1 Solubility: sol a variety of inert solvents. Form Supplied in: 2.2 M solution in dichloromethane. Preparative Methods: Zinc Chloride (20.0 g, 0.147 mol) is dissolved in dry diethyl ether with initial cooling (exothermic!) and shaking, which takes up to 12 h for the more concentrated solutions. These solutions (which are very viscous when less than 30 mL of ether are used) are diluted with CH2Cl2 to obtain the 1.47 M catalyst solutions shown in Table 1. Handling, Storage, and Precautions: the solutions described in Table 1 can be stored at ambient temperature for several months. Precipitation of ZnCl2 takes place when solutions with a [Et2O]/[ZnCl2] ratio <2 are diluted with CH2Cl2 at room temperature. Separation can be avoided by cooling the catalyst solution at −70 °C before addition of the extra solvent and the reactants. The reagent is relatively insensitive toward traces of moisture;1 tentative addition of water causes a similar reduction in the catalytic activity as the same molar amount of ether.1