4-Methylbenzophenone

white to beige crystalline powder or crystals

4-Methylbenzophenone may be used as a reference standard for the determination of the analyte in breakfast cereals, paperboard food packaging and packed milk by various chromatography techniques.

4-Methylbenzophenone is used as clear coatings for wood, plastic and metal, overprint varnish.

Benzophenone estrogenicity toxicity structure activity.

Journal of the American Chemical Society, 82, p. 1223, 1960 DOI: 10.1021/ja01490a047
Tetrahedron Letters, 40, p. 3109, 1999 DOI: 10.1016/S0040-4039(99)00476-1
Synthesis, p. 776, 1977 DOI: 10.1055/s-1977-24573

4-Methylbenzophenone is a photo-initiator for printing inks, mainly applied to the cardboard boxes used for packing. It is reported to be a non-genotoxic carcinogen. However, it can contaminate foodstuffs when it comes in contact with the package contents.

Not classified

Poison by intraperitoneal route. A flammable liquid. When heated to decomposition it emits acrid smoke and irritating fumes.

Crystallise the ketone from MeOH, Et2O (m 58-59o) or pet ether. The cis-oxime has m 154o(153-156o) (from EtOH), and the trans-oxime has m 114-116o (from pet ether). [Beilstein 7 H 440, 7 III 2127, 7 IV 1403.]

4-Methylbenzophenone was one of the first organic compounds for which polymorphism was observed. It crystallizes in two modifications, the stable monoclinic α-form (mp 59°C) and a metastable trigonal β-form (mp 55 ℃). The metastable β-form is rather stable and almost indefinitely preserved if not subjected to severe mechanical load or brought into contact with the stable form. If it converts into a stable form, the crystal becomes milky white and non-transparent due to micro-cracking. There are no conditions under which the β-form is more stable than the α-form. 4-Methylbenzophenone crystallizes in a monoclinic stable form (mp 59 ℃) with a = 5.70 Å, b = 13.89 Å, c = 14.08 Å, p = 95.18° and space group P2_1/c, and a trigonal metastable form (mp 55°C) with a = 9.12 Å, c = 11.28 Å and space groups P3₁, or P3₂[1].

[1] H. Kutzke,  H. Klapper,  M. Al-Mansour. "Stable and metastable crystal phases of 4-methylbenzophenone." Journal of Molecular Structure 374 1 (1995): 129–135.