Isophorone is an α,β-unsaturated cyclic ketone. It is a colorless liquid with a characteristic peppermint-like odor, although commercial samples can appear yellowish. Used as a

solvent A solvent (from the Latin language, Latin ''wikt:solvo#Latin, solvō'', "loosen, untie, solve") is a substance that dissolves a solute, resulting in a Solution (chemistry), solution. A solvent is usually a liquid but can also be a solid, a gas ...

and as a precursor to polymers, it is produced on a large scale industrially.

Structure and reactivity

Isophorone undergoes reactions characteristic of an α,β-unsaturated ketone. Hydrogenation gives the cyclohexanone derivative. Epoxidation with basic

hydrogen peroxide Hydrogen peroxide is a chemical compound with the formula . In its pure form, it is a very pale blue liquid that is slightly more viscosity, viscous than Properties of water, water. It is used as an oxidizer, bleaching agent, and antiseptic, usua ...

affords the oxide. Isophorone is degraded by attack of

hydroxyl radical The hydroxyl radical, •HO, is the neutral form of the hydroxide ion (HO–). Hydroxyl radicals are highly reactive and consequently short-lived; however, they form an important part of radical chemistry. Most notably hydroxyl radicals are pr ...

Photodimerization

When exposed to sunlight in aqueous solutions, isophorone undergoes 2+2 photocycloaddition to give three isomeric photodimers (Figure). These "diketomers" are cis-syn-cis, head to tail (HT), cys-anti-cys (HT), and head-head (HH). The formation of HH photodimers is favored over HT photodimers with increasing polarity of the medium. Available forms of isophorone after a light dependent reaction

Available forms of isophorone after a light dependent reaction

Natural occurrence

Isophorone occurs naturally in

cranberries Cranberries are a group of evergreen dwarf shrubs or trailing vines in the subgenus ''Oxycoccus'' of the genus ''Vaccinium''. Cranberries are low, creeping shrubs or vines up to long and in height; they have slender stems that are not t ...

Synthesis

Isophorone is produced on a multi-thousand ton scale by the

aldol condensation An aldol condensation is a condensation reaction in organic chemistry in which two carbonyl moieties (of aldehydes or ketones) react to form a β-hydroxyaldehyde or β-hydroxyketone (an aldol reaction), and this is then followed by dehydration t ...

acetone Acetone (2-propanone or dimethyl ketone) is an organic compound with the chemical formula, formula . It is the simplest and smallest ketone (). It is a colorless, highly Volatile organic compound, volatile, and flammable liquid with a charact ...

using KOH.

Diacetone alcohol Diacetone alcohol is an organic compound with the formula CH3C(O)CH2C(OH)(CH3)2, sometimes called DAA. This colorless liquid is a common synthetic intermediate used for the preparation of other compounds, and is also used as a solvent. Synthesi ...

mesityl oxide Mesityl oxide is a Carbonyl#.CE.B1.2C.CE.B2-Unsaturated_carbonyl_compounds, α,β-unsaturated ketone with the formula CH3C(O)CH=C(CH3)2. This compound is a colorless, volatile liquid with a honey-like odor. Synthesis It is prepared by the aldol c ...

, and 3-hydroxy-3,5,5-trimethylcyclohexan-1-one are intermediates. A side product is beta-isophorone, where the C=C group is not conjugated with the ketone. Synthesis of Isophorone using a self-condensation reaction

Synthesis of Isophorone using a self-condensation reaction

Applications

The partly hydrogenated derivative trimethylcyclohexanone is used in production of

polycarbonate Polycarbonates (PC) are a group of thermoplastic polymers containing carbonate ester, carbonate groups in their chemical structures. Polycarbonates used in engineering are strong, toughness, tough materials, and some grades are optically transp ...

s. It condenses with phenol to give an analogue of

bisphenol A Bisphenol A (BPA) is a chemical compound primarily used in the manufacturing of various plastics. It is a colourless solid which is Solubility, soluble in most common organic solvents, but has very poor solubility in water. BPA is produced on a ...

. Polycarbonates produced by phosgenation of these two diols produces a polymer with improved thermal stability. Trimethyl

adipic acid Adipic acid or hexanedioic acid is the organic compound with the formula C6H10O4. It a white crystalline powder at standard temperature and pressure. From an industrial perspective, it is the most important dicarboxylic acid at about 2.5 billion ...

and 2,2,4-trimethylhexamethylenediamine are produced from trimethylcyclohexanone and trimethylcyclohexanol. They are used to make specialty

polyamide A polyamide is a polymer with repeating units linked by amide bonds. Polyamides occur both naturally and artificially. Examples of naturally occurring polyamides are proteins, such as wool and silk. Artificially made polyamides can be made throug ...

s. Hydrocyanation gives the nitrile followed by reductive amination gives

isophorone diamine Isophorone diamine (usually shortened to IPDA) is a chemical compound and specifically a diamine with the formula (CH3)3C6H7(NH2)(CH2NH2). It is a colorless liquid. It is a precursor to polymers and coatings. Production It is usually produced as ...

. This diamine is used to produce

isophorone diisocyanate Isophorone diisocyanate (IPDI) is an organic compound in the class known as isocyanates. More specifically, it is an Aliphatic compound, aliphatic diisocyanate. It is produced in relatively small quantities, accounting for (with hexamethylene diis ...

which has certain niche applications. Full hydrogenation gives

3,3,5-Trimethylcyclohexanol 3,3,5-Trimethylcyclohexanol is a precursor to the vasodilator cyclandelate, the sunscreen component homosalate and the VP nerve agent. It can be synthesized by hydrogenation of isophorone. It has a mint flavour. See also * Cyclandelate * VP (ne ...

, a precursor to both sunscreens and chemical weapons.

Safety

The value of isophorone in rats and rabbits by oral exposure is around 2.00 g/kg. The safety aspects of isophorone have been subject to several studies.

History

The use of isophorone as a solvent resulted from the search for ways to dispose of or recycle

, which is a waste product of

phenol Phenol (also known as carbolic acid, phenolic acid, or benzenol) is an aromatic organic compound with the molecular formula . It is a white crystalline solid that is volatile and can catch fire. The molecule consists of a phenyl group () ...

synthesis by the

Hock method The cumene process (cumene-phenol process, Hock process) is an industrial process for synthesizing phenol and acetone from benzene and propylene. The term stems from cumene (isopropyl benzene), the intermediate material during the process. It wa ...

.Isophorone history at Degussa
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References

{{Authority control Enones Ketone solvents Cyclohexenes