Pentaerythrityl tetrabromide

Crude pentaerythrityl tetrabromide, purchased from Columbia Organic Chemicals Company, Inc., was reerystallized from chloroform to separate the tetrabromide as tan needles, m.p. 158-160°. Alternatively, this material may be obtained by the procedure described in a previous volume of this series. ... 

The difficulty in obtaining this monomer in the pure state arises from the fact that the known methods of preparation involve the simultaneous formation of considerable amounts of the isomers of spiropentane which are difficult to remove. The method adopted as giving the most satisfactory yields is that of Applequist, Fanta, and Henrickson (I, 2). The spiropentane is prepared by reaction of zinc dust with pentaerythrityl tetrabromide in alcohol in presence of the sodium salt of ethylenediamine-tetraacetic acid as complexing agent. The yield of hydrocarbon (spiropentane plus various ethylenic compounds) is of the order of 84%. The spiropentane is obtained in the pure state by treating the mixture with bromine in dibromomethane. The yield of pure spiropentane was found to be 62%. 

Benzenesuffonyl esters. That 0S02C Hs is an effective leaving group is illustrated by a procedure for the conversion of pentaerythritol to pentaerythrityl tetrabromide."... 

Sequestration of zinc ions. Spirocyclopentane (3) was discovered by G. Gustavson (1896) as a product of the action of zinc dust on pentaerythrityl tetrabromide (1) in aqueous ethanol. Later workers, chiefly N. D. Zelinsky (1912) and 1. N. Shokhor (1954) investigated the reaction extensively without finding a way to inhibit extensive p CHzBr... 

Derivation Heating pentaerythrityl tetrabromide in ethanol with zinc dust. 

Add pentaerythrityl tetrabromide (20 g, 51.6 mmol, 206 mmol bromide) to the above mixture. 

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