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Acetals are functional groups characterised by an sp3-C that is bonded to two oxygen atoms, which are themselves attached to a carbon atom. We have already seen related structures such as hydrates in earlier lectures. Acetals and hemiacetals are common functional groups in natural products. Some naturally occurring acetals.
A cetals are used as protecting groups for carbonyl groups in organic synthesis because they are stable w ith respect to hydrolysis by bases and w ith respect to many oxidizing and reducing agents.
FUNCTIONAL GROUPS ARE GROUPS OF ATOMS IN ORGANIC MOLECULES THAT ARE RESPONSIBLE FOR THE CHARACTERISTIC CHEMICAL REACTIONS OF THOSE MOLECULES. IN THE GENERAL FORMULAE BELOW, ‘R’ REPRESENTS A HYDROCARBON GROUP OR HYDROGEN, AND ‘X’ REPRESENTS ANY HALOGEN ATOM.
Acetal Structure. Acetal is a functional group with four bonds on the core carbon atom: -OR1, -OR2, -R3, and H. (where R1, R2 and R3 groups are organic fragments). The two –OR groups could be the same (symmetric acetals) or distinct (asymmetric acetals) (mixed acetals). The term Hemiacetal derives from the Greek word “hemi,” which means ...
Figure 2.4 Structures of Amines and Nitriles. Amides C amide acetamide (ethanamide) C N O H C H H N H C H O 2.3 FUNCTIONAL GROUPS THAT CONTAIN NITROGEN. sulfhydryl group in a thiol ... contributing resonance structures of a carbonyl group C O C O 2.11 IDENTIFYING OXYGEN!CONTAINING COMPOUNDS Alcohols and Ethers. Figure 2.13 Infrared Spectrum of ...
Characteristics: polar (N-H group participates in hydrogen bonding, although not as much as a hydroxy group Reactivity: acid-base reactions (tend to act as bases)
A popular reagent to install acetal protecting groups of alcohols is dihydropyran (DHP). The acetal, abbreviated as RO-THP (tetrahydropyranyl), can be installed by acid-catalysis without formation of water
