My understanding of Category:Aldehydes.

Formyl group bonded to sp³ carbon

Synonyms

• Alkanals

Members

Simple n-alkyl aldehydes

1. Formaldehyde
2. Acetaldehyde
3. Propionaldehyde
4. Butyraldehyde
5. Pentanal
6. Hexanal
7. Heptanal
8. Octanal
9. Nonanal
10. Decanal

18. Octadecanal (stearyl aldehyde)

Simple branched alkyl aldehydes

• Isobutyraldehyde (n = 4, isopropyl-CHO)
• 2-Methylundecanal (n = 12, sec-undecyl-CHO)

Non-formyl part is a hydrocarbon but not an alkyl

• Bourgeonal - has a benzene ring separated from CHO by two methylenes
• Citronellal - CHO separated from C=CMe₂ by four sp^{3 carbons}
• Lilial - 2-methylbourgeonal
• Phenylacetaldehyde - Ph—CH₂—CHO
• 3,4-Dihydroxyphenylacetaldehyde - Ar—CH₂—CHO
• Hydroxyisohexyl 3-cyclohexene carboxaldehyde
• Hydroxymethylpentylcyclohexenecarboxaldehyde
• Lactaldehyde - Me—CH(OH)—CHO

Aldols

• Aldol
• 3-Hydroxybutanal - Me—CH(OH)—CH₂—CHO
• Botrydial

Non-hydrocarbon R group

• Chloral - trichloromethyl-CHO (Chloral hydrate is not an aldehyde but a hydrate (1,1-diol / gem-diol)
• Chloroacetaldehyde - chloromethyl-CHO, Cl—CH₂—CHO
• Daigremontianin - complicated steroid but formyl group is bonded to sp³ carbon
• Elenolic acid - complicated natural product but formyl group is bonded to sp³ carbon
• Glycine betaine aldehyde - Me₃N⁺—CH₂—CHO
• Glycolaldehyde - 2-hydroxyacetaldehyde, HO—CH₂—CHO
• cis-3-Hexenal - Et—CH=CH—CH₂—CHO
• k-Strophanthidin - complicated steroid but formyl group is bonded to sp³ carbon
• 2-Methyl-3-oxopropanoic acid - HO₂C—CHMe—CHO
• Neoconvalloside - complicated steroid but formyl group is bonded to sp³ carbon
• Peruvoside - complicated steroid but formyl group is bonded to sp³ carbon
• Succinic semialdehyde - HO₂C—CH₂—CH₂—CHO
• Wieland-Gumlich aldehyde - complicated heterocycle but formyl group is bonded to sp³ carbon

Alkenyl aldehydes

Synonyms

• Enals

Members

Simple ones

• Acrolein - prop-2-enal
• Crotonaldehyde - but-2-enal
• Methacrolein - 2-methylacrolein
• trans-2-Methyl-2-butenal - trans-2,3-dimethylacrolein

Simple but more than one conjugated C=C bond

• (E,E)-2,4-Decadienal

Others

• 2-Amino-3-carboxymuconic semialdehyde
• 2-Aminomuconic semialdehyde
• Cinnamaldehyde - vinylogous benzaldehyde
• Citral
• Coniferyl aldehyde - a vinylogous phenolic aldehyde
• DMACA reagent - 4-H₂N—C₆H₄—CH=CH—CHO
• Formebolone
• Guanacastepene A
• Gyrinal
• Hexyl cinnamaldehyde
• 4-Hydroxynonenal
• 2-Nitrocinnamaldehyde
• Oleocanthal
• Onchidal
• Perillaldehyde
• Picrocrocin
• Retinal
• Retinene
• Safranal
• Sinapaldehyde - enal conjugated to a benzene ring so can be considered a vinylogous benzaldehyde
• Traumatin

Aryl aldehydes

Synonyms

• Formyl aromatics?

Members

Benzaldehydes

• Anisaldehyde - 4-methoxybenzaldehyde
• 3-Acetyl-6-methoxybenzaldehyde
• Ascofuranone
• Benzaldehyde
• Cuminaldehyde - 4-isopropylbenzaldehyde
• 2,5-Dimethoxybenzaldehyde
• para-Dimethylaminobenzaldehyde
• 4-Ethylbenzaldehyde - 4-Et—C₆H₄—CHO
• 4-Methylbenzaldehyde - 4-Me—C₆H₄—CHO
• Nitrobenzaldehyde
  • 2-Nitrobenzaldehyde
  • 3-Nitrobenzaldehyde
• Veratraldehyde

Phenolic aldehydes

Benzaldehydes where one or more of the substituents on the benzene ring is an OH group

• Damnacanthal
• Ethylvanillin
• Gossypol
• Hydroxybenzaldehyde
  • 2-Hydroxybenzaldehyde (better known as salicylaldehyde)
  • 3-Hydroxybenzaldehyde
  • 4-Hydroxybenzaldehyde
• Isovanillin
• Piperonal
• Protocatechuic aldehyde
• Syringaldehyde
• ortho-Vanillin
• Vanillin

Non-benzene aromatic ring

• Furfural - furan—CHO
• Hydroxymethylfurfural
• Methoxymethylfurfural
• Pyridoxal - a decorated pyridine—CHO

Others

O=C—CHO

• Glyoxylic acid - HO₂C—CHO
• Methylglyoxal - acetyl-CHO
• Phenylglyoxal - benzoyl-CHO

N—CHO: formamides

Formamides are not really aldehydes. They're amides.

• Formamide
• Orlistat

Dialdehydes

Two CHO groups separated by alkane chain

• Glyoxal - n = 2, ethanedial, no spacer, OHC—CHO
• Malondialdehyde - n = 3, propanedial, methylene spacer, OHC—CH₂—CHO
• Succindialdehyde - n = 4, butanedial, ethylene spacer, OHC—CH₂—CH₂—CHO
• Glutaraldehyde - n = 5, pentandial, propylene spacer, OHC—CH₂—CH₂—CH₂—CHO

Two CHO groups separated by a non-alkane chain

• Glucic acid - n = 3, 2-hydroxymalondialdehyde, OHC—CH(OH)—CHO
• Polygodial - all hydrocarbon except the two formyl groups

Both CHO groups bonded to a benzene ring

• Phthalaldehyde