Chemistry · Ch 12 — Aldehydes, Ketones and Carboxylic Acids
Classification of aldehydes
Classification of aldehydes
Aldehydes are classified as aliphatic or aromatic depending on what their -CHO (formyl) group is attached to. ALIPHATIC ALDEHYDES are compounds in which the -CHO group is attached directly to an sp3-hybridised (saturated) carbon atom; the general formula is R-CHO where R = H or an alkyl group. There is one deliberate exception to the 'attached to a carbon' rule: formaldehyde, H-CHO, is still classed as an aliphatic aldehyde even though its -CHO is not attached to any carbon atom at all -- it is simply grouped with this family by convention. Worked examples: CH3-CHO is acetaldehyde, and CH3-CH2-CHO is propionaldehyde. AROMATIC ALDEHYDES are compounds in which the -CHO group is attached directly to an aromatic ring. Worked examples: benzaldehyde (a plain -CHO on the ring), salicylaldehyde (a -CHO plus an -OH at the adjacent, o …
Drawn by us to help you understand the concept clearly, and verified to make sure it's accurate. For exams, practice from your textbook's own diagram.
What this figure shows. A carbonyl carbon doubly bonded to O, singly bonded to H, and singly bonded to R (R = H or an alkyl group), i.e. the general skeletal formula R-CHO for any aliphatic aldehyde -- printed beside the worked examples CH3-CHO (acetaldehyde) and CH3-CH2-CHO (propionaldehyde). …
Drawn by us to help you understand the concept clearly, and verified to make sure it's accurate. For exams, practice from your textbook's own diagram.
What this figure shows. Three benzene-ring aldehydes drawn with a -CHO group attached directly to the ring: benzaldehyde (plain -CHO on the ring, no other substituent), salicylaldehyde (a -CHO and an -OH on adjacent, ortho ring positions), and p-nitrobenzaldehyde (a -CHO and a -NO2 group on opposite, para ring …