Ionones

Names

α: (3E)-4-(2,6,6-Trimethylcyclohex-2-en-1-yl)but-3-en-2-one
β: (3E)-4-(2,6,6-Trimethylcyclohex-1-en-1-yl)but-3-en-2-one
γ: (3E)-4-(2,2-Dimethyl-6-methylenecyclohexyl)but-3-en-2-one

Other names

Cyclocitrylideneacetone, irisone, jonon

Identifiers

CAS Number

127-41-3 α^N
79-77-6 β^N
79-76-5 γ^N

3D model (Jmol)

CHEBI:49250^Y

4516050^Y

QP734LIN1K^Y

InChI=1S/C13H20O/c1-10-6-5-9-13(3,4)12(10)8-7-11(2)14/h7-8,12H,1,5-6,9H2,2-4H3/b8-7+^Y

Key: SFEOKXHPFMOVRM-BQYQJAHWSA-N^Y
InChI=1/C13H20O/c1-10-6-5-9-13(3,4)12(10)8-7-11(2)14/h7-8,12H,1,5-6,9H2,2-4H3/b8-7+

Key: SFEOKXHPFMOVRM-BQYQJAHWBW

SMILES

O=C(\C=C\C1\C(=C)CCCC1(C)C)C

Properties

Chemical formula

C₁₃H₂₀O

Molar mass

192.30 g/mol

Density

α: 0.933 g/cm³
β: 0.945 g/cm³

Melting point

β: −49 °C (−56 °F; 224 K)

Boiling point

β: 126 to 128 °C (259 to 262 °F; 399 to 401 K) at 12 mmHg

Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

(what is ^YN ?)

Infobox references

The ionones are a series of closely related chemical substances that are part of a group of compounds known as rose ketones, which also includes damascones and damascenones. Ionones are aroma compounds found in a variety of essential oils, including rose oil. β-Ionone is a significant contributor to the aroma of roses, despite its relatively low concentration, and is an important fragrance chemical used in perfumery. The ionones are derived from the degradation of carotenoids.

The combination of α-ionone and β-ionone is characteristic of the scent of violets and used with other components in perfumery and flavouring to recreate their scent.

The carotenes α-carotene, β-carotene, γ-carotene, and the xanthophyll, and β-cryptoxanthin, can all be metabolized to β-ionone, and thus have vitamin A activity because they can be converted by plant-eating animals to retinol and retinal. Carotenoids that do not contain the β-ionone moiety cannot be converted to retinol, and thus have no vitamin A activity.

Carotenoids are the precursors of important fragrance compounds in several flowers. For example, a 2010 study of ionones in Osmanthus fragrans Lour. var. aurantiacus determined its essential oil contained the highest diversity of carotenoid-derived volatiles among the flowering plants investigated. A cDNA encoding a carotenoid cleavage enzyme, OfCCD1, was identified from transcripts isolated from flowers of O. fragrans Lour. The recombinant enzymes cleaved carotenes to produce α-ionone and β-ionone in in vitro assays.

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