P R E P A R A T I O N A N D C H E M I S T R Y OF EPOXY ALCOHOLS KENNETH ALLISON, PETER JOHNSON, GORDON FOSTER, A N D M A U R I C E B. S P A R K E Chemicals Division, B P Research Centre, The British Petroleum Co., Ltd., Chertsej Road, Sunbury-on-Thames, Middlesex, England
A new reaction has been discovered in which allylic hydroperoxides formed by olefin autoxidation are catalytically rearranged to epoxy alcohols. Epoxy alcohol-forming catalysts are transition elements of Groups 4, 5, and 6 of the Periodic Table and their compounds, excluding chromium. Vanadium, molybdenum, and tungsten compounds are especially active. The epoxy alcohols can b e produced either by a twostep process in which the hydroperoxides are formed and rearranged in separate steps, or in a single step by olefin autoxidation in the presence of an epoxy alcohol-forming catalyst. A range of olefins has been investigated. High yields (90to 100 weight %) of a mixture of two epoxy alcohols-2-methyl-3,4-epoxypentan-2-01 (I)and 4-methyl-3,4-epoxypentan-2-ol (11)-have been realized with 4-methyl-2-penteneI and a wide range of derivatives of potential commercial utility has been prepared from I and II by reaction at both the epoxide and hydroxyl groups.
HE
formation of epoxy alcohols by the catalytic rearrange-
Tment of allylic hydroperoxides was first observed during
work on the autoxidation of the rnethylpentenes. This paper gives details of a program of experimental work to investigate the scope of the epoxy alcohol reaction and to prepare epoxy alcohol derivatives of potential commercial significance. Allylic hydroperoxides can be major products of the low temperature liquid-phase oxidation of olefins with molecular oxygen and hydroperoxide yields of 60 to 100 mole yo have been reported (8, 72). I t has been shown (3,4) that autoxidation of olefins follows a radical chain mechanism: Initiation Propagation
RH ---t R * R. 0 2 -t ROZ. ROz. RH + ROzH
Termination
2R02.
+
+ ROa. + R . 2R *
1
+R*
+ inactive
products
where R . is the allylic radical derived by hydrogen abstraction from the C atom (Y to the double bond-Le., -HC=CH-CH-CH-CH-. For simple nonpolyCH2merizable olefins the ease of hydroperoxide formation tends to parallel the bond dissociation energy of the C-H bonds CY to the double bond, so that observed hydroperoxide yields tend to increase (1) in the order primary secondary tertiary for the (Y-C-H bonds and (2) as the double bond moves away from the terminal position or becomes part of a n alicyclic system (3, 77). As well as unsaturated entities such as allylic hydroperoxides and their decomposition products, unsaturated alcohols and ketones, saturated products-e.g., epoxides (6, 73) and polyperoxides (78)-have been observed as major products of olefin autoxidation. The accepted radical mechanism of epoxide formation in autoxidation was proposed by Twigg (24):
*
