HIBBERT

Safrole (5-allyl-l,3-benzodioxole, 4-allyl-l,2-methylenedioxybenzene) [94-59-7] M 162.1, m- 11 , b 69-70 /1.5mm, 104-105 /6mm, 231.5-232 /atm, 235-237 /atm, dj 1.0993, n, 1.53738. It has been purified by fractional distn, although it has also been recrystd from low boiling pet ether at low temperatures. [IR Briggs et al. Anal Chem 29 904 19S7 UV Patterson and Hibbert J Am Chem Soc 65 1962 1943.] The maleic anhydride adduct forms yellow crystals from toluene m 257° [Hickey J Org Chem 13 443 1948], and the picrate forms orange-red crystals from CHCI3 [Baril and Magrdichian 7/4m Chem Soc 5S 1415 1936]. 

Hibbert and Burt dissolved the benzoylperoxide in dry ether, cooled to — 50 and added the calculated amount of a 10 per cent sodium ethylate solution, maintaining the low temperature during the procedure. Sufficient ice water was added to give a clear solution, the ether containing the ethyl benzoate separated and the aqueous sodium benzoylperoxide solution added slowly with stirring to twice the necessary amount of cold 20 per cent sulfuric acid (reaction mixture always at o°). The oily layer of benzoylhydroperoxide was then extracted three times with chloroform and the extract dried over anhydrous sodium sulfate. 

This procedure was carried out by the checkers and compared with Tiffeneau s procedure. Tiffcneau s directions seem preferable for the following reasons. There was much less tendency to form an emulsion when the sodium salt was extracted with ether. The emulsion in Hibbert s methods was frequently persistent and the solution became warm before the aqueous solution could be separated from the ether, thus causing decomposition. A 10 per cent solution of sodium ethylate is difficult to handle for it crystallizes and cannot be added from a separatory funnel. If more alcohol is added the tendency toward formation of the emulsion is increased. 

Styrene oxide has previously been prepared by the action of iodine, water and mercuric oxide on styrene.1 A description of Hibbert s method 2 using benzoylhydroperoxide has appeared... 

The formation of arynes (8.26) as metastable intermediates in aromatic dediazo-niations was postulated by Stiles and Miller (1960) for the case of the 2-carboxy-benzenediazonium zwitterion (8.25) and by Cadogan and Hibbert (1964) for unsubstituted benzenediazonium salts. ... 

Hewlett, J. D. and Hibbert, A. R. (1967) Factors affecting the response of small watersheds to precipitation in humid areas. In "International Symposium on Forest Hydrology" (W. E. Sopper and W. H. Lull, eds), pp. 275-290. Pergamon, New York. 

For a review of the acidity of cyano compounds, see Hibbert, F. in Patai Rappoport The Chemistry of Triple-bonded Functional Groups, pt. 1 Wiley NY, 1983, p. 699. 

For reviews of such proton transfers, see Hibbert, F. Adv. Phys. Org. Chem., 1986,22,113 Crooks, J.E. in Bamford Tipper Chemical Kinetics, vol. 8 Elsevier NY, 1977, p. 197. Kinetic studies of these very fast reactions were first carried out by Eigen. See Eigen, M. Angew. Chem. Int. Ed. Engl., 1964, 3, 1. 

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