Ionone 1771473 224813215 2008-07-10T15:08:22Z 148.177.1.218 redundant {{Chembox new | Name = Ionones | ImageFileL1 = alpha-ionone-label.png | ImageNameL1 = alpha-ionone | ImageSizeL1 = 120px | ImageFileR1 = beta-ionone-label.png | ImageNameR1 = beta-ionone | ImageSizeR1 = 120px | ImageFile2 = gamma-ionone-label.png | ImageName2 = gamma-ionone | ImageSize2 = 120px | IUPACName = α: (3''E'')-4-(2,6,6-Trimethylcyclohex-2-en-1-yl)but-3-en-2-one<br />β: (3''E'')-4-(2,6,6-Trimethylcyclohex-1-en-1-yl)but-3-en-2-one<br />γ: (3''E'')-4-(2,2-Dimethyl-6-methylenecyclohexyl)but-3-en-2-one | OtherNames = Cyclocitrylideneacetone, irisone, jonon | Section2 = {{Chembox Properties | Formula = C<sub>13</sub>H<sub>20</sub>O | MolarMass = 192.30 g/mol | Density = α: 0.933 g/cm<sup>3</sup><br />β: 0.945 g/cm<sup>3</sup> | MeltingPt = β: -49 °C | BoilingPt = β: 126-128 °C at 12 mmHg | CASOther = α: 127-41-3<br />β: 79-77-6<br />γ: 79-76-5 | SMILES = α: C\C1=C\CCC(C)(C)C1/C=C/C(C)=O<br />β: CC1(C)CCCC(\C)=C1\C=C\C(C)=O<br />γ: C=C1CCCC(C)(C)C1/C=C/C(C)=O}} }} The '''ionones''' are a series of closely related [[chemical substance]]s that are part of a group of compounds known as rose ketones, which also includes [[damascone]]s and [[damascenone]]s. Ionones are [[aroma compound]]s found in a variety of [[essential oil]]s, including [[rose oil]]. ''beta''-Ionone is a significant contributor to the aroma of roses, despite its relatively low concentration, and is an important fragrance chemical used in perfumery.<ref>[http://www.leffingwell.com/rose.htm Rose (Rosa damascena)], John C. Leffingwell</ref> ''beta''-Ionone is also a raw material for the production of [[retinol]]. Biochemically, the ionones are derived from the degradation of [[carotenoid]]s. ==Organic synthesis== Ionone can be [[organic synthesis|synthesised]] from [[citral]] and [[acetone]] with [[calcium oxide]] as a basic [[heterogeneous catalysis]] and serves as an example of an [[Aldol condensation]] followed by a [[rearrangement reaction]].<ref>{{cite journal | author=NODA, C., ALT, G. P., WERNECK, R. M. et al. |title=Aldol Condensation of Citral with Acetone on Basic Solid Catalysts|journal=Braz. J. Chem. Eng. |year=1998 |volume =15 |issue=2 |url= http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0104-66321998000200004 |doi=10.1590/S0104-66321998000200004}}</ref><ref>{{cite journal| title= Pseudoionone |author=Alfred Russell and R. L. Kenyon |journal=[[Organic Syntheses]], Coll. Vol. 3 |volume=23 |pages=78 |url=http://www.orgsyn.org/orgsyn/default.asp?dbname=orgsyn&dataaction=search&metadata_directive=blind_gui&formgroup=quick_form_group&Preps.CollVol=3&Preps.CollPage=747&order_by=Preps.CollPage%20ASC}}</ref> The [[nucleophilic addition]] of the [[carbanion]] '''3''' of acetone '''1''' to the [[carbonyl]]group on citral '''4''' is [[base (chemistry)|base]] [[catalysis|catalysed]]. The [[aldol condensation]] product '''5''' [[elimination reaction|eliminates]] water through the [[enolate ion]] '''6''' to the pseudoionone '''7'''. [[Image:iononone3.gif]] The reaction proceeds by [[acid]] catalysis where the [[double bond]] in '''7''' opens to form the [[carbocation]] '''8'''. A [[rearrangement reaction]] of the carbocation follows with ring closure to '''9'''. Finally a hydrogen atom can be abstracted from '''9''' by an acceptor molecule ('''Y''') to form either '''10''' (extended [[conjugated system]]) or '''11'''. [[Image:ionone4.gif]] ==References== {{reflist}} [[Category:perfume ingredients]] [[Category:flavors]] [[Category:Ketones]] [[Category:Terpenes and terpenoids]] [[de:Jonon]] [[fr:Ionone]] [[nl:Jonon]] [[ja:イオノン]] [[pl:Jonon]] [[pl:Jonony]]