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Date: 10-7-2018
3437
Date: 6-9-2019
730
Date: 23-6-2016
2802
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The reactivity of aromatic pi bonds in SEAr reactions is very sensitive to the presence of electron-donating groups (EDG) and electron-withdrawing groups (EWG) on the aromatic ring. This is due to the carbocation nature of the intermediate, which is stabilized by electron-donating groups and destabilized by electron-withdrawing groups. As a rule, both the acylation and alkylation Friedel-Crafts reactions fail when meta-directing deactivators are present. Thus nitrobenzene (a deactivated ring) fails to react in the Friedel-Crafts reaction. However the reaction is successful with halogen substituents are present, as in chlorobenzene.
The Friedel-Crafts alkylation of methoxy benzene would be expected to produce a mixture of the ortho and para substituted products, but no meta-substituted product.
In addition, the para product would be expected to be preferred over the ortho product, due to steric and inductive considerations.
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تفوقت في الاختبار على الجميع.. فاكهة "خارقة" في عالم التغذية
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أمين عام أوبك: النفط الخام والغاز الطبيعي "هبة من الله"
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قسم شؤون المعارف ينظم دورة عن آليات عمل الفهارس الفنية للموسوعات والكتب لملاكاته
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