In organic chemistry, OTs represent tosylate. It is a functional group generated by the loss of hydrogen from the OH group in para-toluenesulfonic acid.
These are utilized to convert alcohol or amine into an effective leaving group. In organic chemistry, OTs represent tosylate. Converting alcohols to a sulfonate ester, such as OTs or OMs, is one method for converting them to good leaving groups.
Tosylate groups are effective leaving groups because their conjugate base forms are remarkably stabilized by resonance: Bonding, Organic Chemistry, Hybridization of Atomic Orbitals, Sigma and Pi Bonds, Sp Sp2 Sp3, Sp Sp2 Sp3.
Tosylateanother Good Leaving Group
Alternately, we can convert an alcohol group into a sulfonic ester by employing para-toluene sulfonyl chloride or methanesulfonyl chloride, therefore producing an organic tosylate or mesylate:
In the chapter 12 tasks, you’ll have another opportunity to devise a method to produce tosylate and mesylate. Note, however, that unlike the halogenation processes described above, converting an alcohol to a tosylate or mesylate happens with the electrophilic carbon retaining its structure.
Due to resonance delocalization of the growing negative charge on the leaving oxygen, chlorides, bromides, and tosylate/mesylate groups are outstanding leaving groups in nucleophilic substitution processes.
The laboratory synthesis of isopentenyl diphosphate, the ‘building block’ molecule used by nature to construct isoprenoid molecules such as cholesterol and b-carotene, was achieved by first converting the alcohol into an organic tosylate and then displacing the tosylate group with an inorganic pyrophosphate nucleophile.
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