McMurry (Kap 14.0-14.1) - Aldehydes and Ketones, naming

Question 1

Aldehydes and ketones, are they carbonyl compounds? And are they rare in living organisms?

Answer 1

Yes, they both contain O atom.

They are very abundant, especially in living organisms, as they are intermediates in the synthesis of many pharmaceutical agents, and in almost all biological pathways.

In nature, many substances required by living organisms are aldehydes or ketones (coenzymes, hormones etc).

Question 2

How is formaldehyde (the simplest aldehyde of one c-atom bound to two H atoms and double bond to one O-atom) produced?

Answer 2

It is produced by catalytic oxidation of methanol, and acetone is oxidation of propan-2-ol.

(oxidation of alcohol to aldehyde or ketone).

Question 3

Naming aldehydes and ketones (page 493-494)

How are aldehydes named?

Common names for simple aldehydes (page 493)

Answer 3

By replacing the terminal -e with -al. The parent chain must contain the aldehyde group, and the C containing the aldehyde group is numbered 1.

Ethanal, Propanal, 2-ethyl-4-methylpentanal etc.

(for cykliske aldehyder) - where the aldehyde group is attached to the ring, the suffix -carbaldehyde is used (cyclohexanecarbaldehyde etc.).

Question 4

How are ketones named?

Answer 4

By replacing the terminal -e of an alkane name with an -one.

The parent chain is the longest chain that contains the ketone group, and the numbering begins in the end nearer to the ketone group.

The numerical locant is placed before the suffix in IUPAC recommendation (Hexan-3-one, Hex-4-en-2-one etc).

(Reffering to an ketone as a substituent, the name acyl group is used).
- the name ending -yl.
(acetyl, formyl, benzoyl).

If a ketone is considered a side chain in an open chain, and other functional groups are present, the prefix oxo is used - Methyl 3-oxohexanoate.