Benzophenone

Structural formula
General
Surname	Benzophenone
other names	Diphenyl ketone Diphenylmethanone Benzoylbenzene
Molecular formula	C 13 H 10 O
Brief description	colorless solid with a geranium-like odor
External identifiers / databases
CAS number 119-61-9 EC number 204-337-6 ECHA InfoCard 100.003.943 PubChem 3102 DrugBank DB01878 Wikidata Q409482
properties
Molar mass	182.22 g mol −1
Physical state	firmly
density	1.15 g cm −3 (α modification at 20 ° C) 1.11 g cm −3 (β modification)
Melting point	49 ° C
boiling point	305 ° C
solubility	slightly soluble in water (23 mg l −1 at 25 ° C) Easily soluble in diethyl ether , ethanol , trichloromethane
safety instructions
GHS labeling of hazardous substances Caution H and P phrases H: 373-412 P: 260-273-281-308 + 313-391-501
As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

Benzophenone ( IUPAC name diphenylmethanone ) is an organic compound that belongs to the groups of ketones and aromatics .

Extraction and presentation

Benzophenone can be synthesized either by the reaction of benzene with carbon tetrachloride and the subsequent hydrolysis of the resulting diphenylmethylene chloride or by Friedel-Crafts acylation of benzene with benzoyl chloride in the presence of a Lewis acid (e.g. aluminum chloride ). The latter method allows the synthesis of asymmetrically substituted benzophenones in very high yields.

properties

Physical Properties

Benzophenone forms colorless rhombic crystals that melt at 49 ° C. The compound boils at 305 ° C. under normal pressure . According to Antoine, the vapor pressure function results from log ₁₀ (P) = A− (B / (T + C)) (P in bar, T in K) with A = 4.36238, B = 2116.372 and C = −93 , 43 in the temperature range from 474 to 579 K The most important thermodynamic properties are listed in the following table:

property	Type	Value [unit]
Standard enthalpy of formation	Δ f H 0 gas Δ f H 0 solid	49.9 kJ mol −1 −34.48 kJ mol −1
Enthalpy of combustion	Δ c H 0 solid	−6510.3 kJ mol −1
Heat capacity	c p	224.80 J mol −1 K −1 (25 ° C) as a solid
Enthalpy of fusion	Δ f H 0	18.194 kJ mol −1 at the melting point
Entropy of fusion	Δ f S 0	56.67 kJ mol −1 at the melting point
Enthalpy of evaporation	Δ V H 0	94.977 kJ mol −1 at 25 ° C
Critical temperature	T C	830 K
Critical pressure	P C	33.52 bar
Critical density	ρ C	1.762 mol·l −1

use

Benzophenone is used as a photoinitiator in UV curing applications such as inks and coatings in the printing industry.

As an ingredient in cosmetics, it protects fragrances and colors in products such as creams, perfumes, soaps or even plastic packaging from being destroyed by UV radiation.

On a laboratory scale, it is used as an indicator for drying organic solvents with sodium. This reduces benzophenone to the deep blue ketyl radical , which is moderately stable in the absence of water and oxygen.

Derivatives

Oxybenzone , a derivative of benzophenone, is approved as UV protection in sun creams according to the German Cosmetics Ordinance . There it is referred to as "benzophenone-3" and can cause allergies.

safety instructions

The International Agency for Research on Cancer (IARC) classified benzophenone as a possible carcinogen in 2013.

Benzophenone was included in the EU's ongoing action plan ( CoRAP ) in 2013 in accordance with Regulation (EC) No. 1907/2006 (REACH) within the framework of substance evaluation . The effects of the substance on human health and the environment are re-evaluated and, if necessary, follow-up measures are initiated. The reasons for the inclusion of benzophenone were concerns about consumer use , high risk characterization ratio (RCR) and widespread use as well as the dangers arising from a possible assignment to the group of CMR substances. The re-evaluation took place from 2013 and was carried out by Denmark . A final report was then published.

Individual evidence

1. ↑ ^{a b c d e f g h i} Entry on benzophenone in the GESTIS substance database of the IFA , accessed on February 1, 2016(JavaScript required) .
2. ↑ ^{a b c d} Entry on benzophenone. In: Römpp Online . Georg Thieme Verlag, accessed on June 19, 2014.
3. ↑ CS Marvel, WM Sperry: Benzophenone In: Organic Syntheses . 8, 1928, p. 26, doi : 10.15227 / orgsyn.008.0026 ; Coll. Vol. 1, 1941, p. 95 ( PDF ).
4. ↑ C.-W. Schellhammer In: Klaus-Dieter Bode, Eugen Müller, Josef Houben, Theodor Weyl (Eds.): Methods of organic chemistry. Volume 7 / 2a, Thieme-Verlag 1973, ISBN 3-13-206004-6 , p. 15.
5. ^ RR Dreisbach, SA Shrader: Vapor Pressure-Temperature Data on Some Organic Compounds. In: Ind. Eng. Chem. 41, 1949, pp. 2879-2880, doi: 10.1021 / ie50480a054 .
6. ^ ^{A b c} R. Sabbah, M. Laffitte: Etude thermodynamique de la molecule de benzophenone. In: Thermochim. Acta . 23, 1978, pp. 196-198, doi: 10.1016 / 0040-6031 (78) 85128-4 .
7. ↑ ^{a b c} C. G. DeKruif, JC Van Miltenburg, JG Blok: Molar heat capacities and vapor pressures of solid and liquid benzophenone. In: J. Chem. Thermodynam. 15, 1983, pp. 129-136, doi: 10.1016 / 0021-9614 (83) 90151-9 .
8. ↑ K. Neumann, E. Volker: A rotating balance method for measuring the smallest vapor pressures. In: Z. Phys. Chem. 161, 1932, pp. 33-45.
9. ^ ^{A b c} W. V. Steele, RD Chirico, IA Hossenlopp, SE Knipmeyer, A. Nguyen, NK Smith: DIPPR project 871. Determination of ideal gas enthalpies of formation for key compounds. The 1990 project results, Experimental Results for DIPPR 1990-91 Projects on Phase Equilibria and Pure Component Properties. In: DIPPR Data Ser. No. 2, 1994, pp. 188-215.
10. ↑ A. Darvay, IR White, RJ Rycroft, AB Jones, JL Hawk, JP McFadden: Photoallergic contact dermatitis is uncommon. In: Br J Dermatol . 145 (4), 2001, pp. 597-601. PMID 11703286 .
11. ↑ IARC Monograph 101 - Benzophenone , 2013
12. ↑ European Chemicals Agency (ECHA): Substance Evaluation Conclusion and Evaluation Report .
13. ↑ Community rolling action plan ( CoRAP ) of the European Chemicals Agency (ECHA): Benzophenone , accessed on March 26, 2019.