Structure Of The Two Ketone Groups

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Prednisolone
1. Structure

The two ketone groups will be sp2 hybridised and so are the carbon-to-carbon (C-to-C) double bonds. The carbon atoms that are part of alkanes and the alcohol groups will be sp3 hybridised. There isn’t any resonance in the molecule.

2. Functional Groups
There are 3 different functional groups, excluding the alkane and cycloalkanes. There are two aliphatic ketones and three aliphatic alcohols along with a cyclohexadiene, where one of the ketones is found. The alcohols are secondary, tertiary and primary as you go from left to right of the molecule.
3. Conformation of prednisolone 4. Stereochemistry in prednisolone
Prednisolone has 7 chiral centres, which would give rise to 128 possible stereoisomers. There are also two C-to-C double bonds, however because they are part of a ring, they wouldn’t give rise to any geometrical isomers.
5. Acidic or basic functional groups in the drug
Prednisolone is a neutral molecule. Alcohol groups are mildly acidic and could theoretically act as an acid at a high pH, but that would happen very rarely, certainly not at physiological pH. There are no basic groups in Prednisolone.

6. Ionisation state of the drug in the stomach (pH of 2) and blood (pH of 7.4)
Prednisolone would remain in this neutral state both at pH 2 and at pH 7.4. This is because its strongest acid pKa is 12.59 (the tertiary alcohol; the primary and the secondary alcohols have pKa values of 13.87 and 14.93 respectively). Hence, the hydroxyl
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