1-Hydroxycyclohexyl phenyl ketone

Chemical Properties

Solid

Uses

1-Hydroxycyclohexyl phenyl ketone is used as photoinitiator in UV-radiation-curable technologies which are used in various applications and industry branches such as printing and packaging, coatings, furniture and flooring and adhesives.

Synthesis Reference(s)

Journal of the American Chemical Society, 89, p. 3084, 1967 DOI: 10.1021/ja00988a072

General Description

1-Hydroxycyclohexyl phenyl ketone is a photoinitiator (PI) molecule that can be used in chain transfer polymerization. PI can be incorporated in the polymeric matrix by the addition of a chromophore as a pendant group. It may be used as a component that facilitates UV curing and also as a base material in the formation of the block and grafted copolymers.

Flammability and Explosibility

Not classified

Synthesis

1) Acylation: Add cyclohexylcarboxylic acid to the reactor vessel and raise the temperature to 352C. Add phosphorus trichloride, maintain at 602C for at least 4 hours, then separate off the inorganic layer to obtain cyclohexanecarboxylic acid chloride. The weight ratio of cyclohexylcarboxylic acid to phosphorus trichloride is 1.8C2.2:1;

2) Friedel-Crafts reaction: Add benzene and aluminium trichloride catalyst to the reactor vessel. Upon cooling to 5C10C, slowly add the cyclohexyl chloroformate obtained in step (1). The weight ratio of benzene, aluminium trichloride to cyclohexyl formyl chloride is 9:2.9C3.1:3.16C3.36. Reaction at 152C for at least 2.5 hours yields cyclohexylphenyl ketone and an aluminium trichloride complex;

3) Hydrolysis reaction: Add an appropriate amount of dilute hydrochloric acid (1.5C2.5% mass concentration) to the complex. Stir to separate layers, decant the aqueous layer containing aluminium trichloride, then add an appropriate amount of water to wash out acid until pH > 5. Finally, remove unreacted benzene feedstock by distillation to obtain cyclohexyl phenyl ketone;

4) Chlorination reaction: Add cyclohexylphenyl methyl ketone to the chlorination reactor, raise temperature to 602C, then introduce chlorine gas until reaction completion to yield 1-chloro-cyclohexylphenyl methyl ketone;

5) Alkylation reaction: Add 1-chlorocyclohexyl phenyl ketone to caustic soda solution at a weight ratio of 1:0.95C1.10. Stir until reaction completion, then add toluene for extraction. Separate the aqueous phase, remove solvent, recover toluene, yielding 1-hydroxycyclohexyl phenyl ketone.;

6) Purification: Place the crude product in a distillation flask, reduce pressure, distil the product, and collect the distillate; Transfer the distilled product to a crystallisation vessel, dissolve and recrystallise using petroleum ether, then separate by centrifugation. Distil the mother liquor to recover the petroleum ether solvent for reuse. Dry the wet product to obtain the finished 1-hydroxycyclohexyl phenyl ketone.

Toxics Screening Level

The initial threshold screening level (ITSL) for 1-hydroxcyclohexyl phenyl ketone is 0.1 μg/m3 based on an annual averaging time.