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Alternatively, we can transform an alcohol group into sulfonic ester using para-toluene sulfonyl chloride (Ts-Cl) or methanesulfonyl chloride (Ms-Cl), creating what is termed an organic tosylate or mesylate:
Again, you’ll have a chance to work a mechanism for tosylate and mesylate formation in the chapter 12 problems. Notice, though, that unlike the halogenation reactions above, conversion of an alcohol to a tosylate or mesylate proceeds with retention of configuration at the electrophilic carbon.
Chlorides, bromides, and tosylate / mesylate groups are excellent leaving groups in nucleophilic substitution reactions, due to resonance delocalization of the developing negative charge on the leaving oxygen.
The laboratory synthesis of isopentenyl diphosphate - the 'building block' molecule used by nature for the construction of isoprenoid molecules such as cholesterol and b-carotene - was accomplished by first converting the alcohol into an organic tosylate (step 1), then displacing the tosylate group with an inorganic pyrophosphate nucleophile (step 2).
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تجربة بسيطة مدتها 3 دقائق تحسن النظر كثيرا
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الصين.. تطوير محفز نانوي رخيص الثمن لتنقية المياه من النترات
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بحضور علمائي ورسمي .. العتبة العلوية المقدسة ترفع راية الحزن والحداد إيذاناً بحلول شهر محرم الحرام
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