Alkylation of hafnium tetrachloride with benzyl Grignard; Hafnium tetrabenzyl ; Group 4 tetrabenzyl

Ian Westmoreland ([email protected]),
A contribution from the Scott Group, Warwick

Chemicals Used
Benzylmagnesium chloride (Aldrich) HfCl₄ (sublimed) Diethyl ether (dried over Na/K) Heptane (dried over K)

Procedure
HfCl₄ (7.7 g, 24.0 mmol) was suspended in diethyl ether (100 ml) and stirred for 1 hour. The suspension was then cooled to -78 ^oC and the Grignard (100 ml, 1.0 M in diethyl ether) was added dropwise over 30 min. The creamy off-white mixture obtained was stirred overnight in the dark (use aluminium foil). After this time a the solution had turned yellow. The solvent was removed under vacuum, and the residue was extracted with warm heptane (3 x 75 ml). The combined extracts were concentrated to ca. 100 ml and cooled to -30 ^o C. The product is obtained as fine yellow needles after cooling for several hours at this temperature. Yield = 10 g, 78%

Author's Comments
Standard Schlenk procedures are applied throughout. Unlike the zirconium anologue, the MgCl by-product forms the ether adduct during this reaction, which cannot be removed by fritt filtration. This necessitates the extraction procedure described; hexane is an adequate alternative to heptane. A slight excess of the Grignard reagent is used to ensure complete reaction of the chloride. We store the product in a freezer, and transfer it to the glovebox to handle it.

Data
¹H NMR (293 K, d6-benzene)7.21 (8H, t, ArH), 7.07 (4H, t, ArH), 6.65 (8H, d, ArH), 1.62 (8H, s, CH2)

Lead Reference
J. J. Felten and W. P. Anderson, J. Organomet. Chem. 1972, 36, 87.

Other References

This page has been viewed approximately 1514 times since records began.

Get CDX file (Choose "Open this file from its current location" TWICE)

SyntheticPages^TM are for use exclusively by those with training and experience in synthetic chemistry. While contributors are asked to identify hazards and to use methods designed to reduce risk, no formal hazard or risk assessments are included, and these procedures must be conducted at one's own risk. SyntheticPages, its editors, owners and associates do not warrant or guarantee the safety of individuals using these procedures and hereby disclaim any liability for any injuries or damages claimed to have resulted from or related in any way to the procedures herein. Copyright ©2005 Synthetic Pages

Comment on this page!