Which epoxide is more stable?
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Which epoxide is more stable?
The epoxide metabolites of alkenes tend to be more stable than arene oxides. They undergo a ring opening with water to give diols. One example of this type of reaction is the ring opening of the epoxide of the anticonvulsant drug carbamazepine.
Under what conditions will a nucleophile attack the more substituted carbon of an epoxide?
Notice, however, how the regiochemical outcome is different from the base-catalyzed reaction: in the acid-catalyzed process, the nucleophile attacks the more substituted carbon because it is this carbon that holds a greater degree of positive charge.
How do you break open epoxide?
Epoxides can also be opened by other anhydrous acids (HX) to form a trans halohydrin. When both the epoxide carbons are either primary or secondary the halogen anion will attack the less substituted carbon and an S N2 like reaction.
Why does nucleophile attack more substituted carbon?
The nucleophile attacks the more substituted carbon, because the carbon is more positively polarized than the other carbon.
What is epoxide ring-opening?
Epoxides are three-membered rings containing an oxygen atom. They are associated with high ring tension and this is the basis of their reactivity towards nucleophiles despite lacking a good leaving group. These features make peroxides undergo ring-opening reactions with strong or weak nucleophiles.
What reagent breaks an epoxide?
For example, aqueous acid [often abbreviated “H3O+”] will open an epoxide under MUCH milder conditions than an “ordinary” ether such as diethyl ether, because epoxides have considerable ring strain [about 13 kcal/mol].
Which reagent S will result in the nucleophile attacking the more substituted side of an epoxide?
Experimental results show that scenario 2 is observed by these stronger nucleophiles such as Grignard reagents, RMgBr. Reactive nucleophiles attack the least hindered end of the epoxide in an SN2 type fashion at 180o to the leaving group bond. This results in the formation of the more substituted alcohol.