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Date: 11-1-2020
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Date: 2-10-2020
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Date: 8-10-2020
1925
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As the table below shows, the dissociation energy for the allylic C-H bond is lower than the dissociation energies for the C-H bonds at the vinylic and alkylic positions. This is because the radical formed when the allylic hydrogen is removed is resonance-stabilized. Hence, given that the halogen concentration is low, substitution at the allylic position is favored over competing reactions. However, when the halogen concentration is high, addition at the double bond is favored because a polar reaction outcompetes the radical chain reaction.
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إدارة الغذاء والدواء الأميركية تقرّ عقارا جديدا للألزهايمر
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شراء وقود الطائرات المستدام.. "الدفع" من جيب المسافر
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العتبة العبّاسيّة: البحوث الّتي نوقشت في أسبوع الإمامة استطاعت أن تثري المشهد الثّقافي
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