Octabenzone: an effective ultraviolet light absorber

Octabenzone is an ultraviolet light absorber (UVA) of the benzophenone class, imparting good light stability for plastics and other organic polymers. Due to its highly effective broad UV absorption properties and excellent polymer compatibility, Octabenzone offers maximum polymer protection and low color contribution, retards yellowing and loss of physical properties.

Synthesis of Octabenzone

Put 160.0g of chloro-n-octane into a reactor equipped with a thermometer and a stirring device. The temperature is raised to 98°C, and 110.0g of 2,4-dihydroxybenzophenone, 15.0g of PEG-600, and potassium carbonate are successively added under stirring. 0.86g, 31.0g of sodium carbonate, continue to stir and heat to 120°C after casting, reflux and separate water, cool down after reflux and separation, add appropriate amount of water to the resulting system for washing, stand still for layering, oil layer distillation to obtain product Octabenzone, the purity by gas chromatography was 99.1%, and the yield was 95.3%.[1]

Oral chemoprevention of skin cancer in mice by octabenzone in drinking water

Sunscreen compounds with added benefit of skin cancer prevention have both public and commercial interests. Our earlier study using the Epstein-Barr virus early antigen in vitro assay reported on skin cancer chemoprevention potential of benzophenone sunscreens. We now report the in vivo antitumor activity of two of the benzophenone sunscreens which tested positively in the in vitro assay, octabenzone (UV-1) and dioxybenzone (UV-2), in the two-stage mouse skin carcinogenesis model using (±)-(E)-4-methyl-2-[-(E)-hydroxyamino]-5-nitro-6-methoxy-3-hexanamide (NOR-1) as inducer and 12-O-tetradecanoyl-phorbol-13-acetate (TPA) as promoter. Materials and Methods: Pathogen-free, female hairless mice of HOS:HR-1 strain, 15 animals per control and test groups, were used. Skin tumors were induced by a single dose of NOR-1 (390 nmol in 100 μl of acetone). One week later, TPA (1.7 nmol in 100 μl of acetone) was applied to skin twice weekly for 20 weeks as tumor a promoter. The test compounds Octabenzone or UV-2 were administered at 0.0025% to mice through drinking water ad libitum, starting one week prior to and stopping one week after tumor initiation. All animals were examined weekly for the development of skin papillomas. Results: In both UV-1- and UV-2-treated mice, a two-week delay in tumor appearance, and significant inhibition (p<0.001) of tumor incidence (50% and 60%, respectively) and tumor burden (papilloma inhibition/mouse, 50% and 70%, respectively) were observed when compared to the positive control group. UV-2 (dihydroxy derivative) was a more potent inhibitor of skin tumor than Octabenzone (monohydroxy derivative), which followed their antioxidant activity ranking. Conclusion: The results affirm the skin cancer chemoprevention potential of orally-ingested benzophenone sunscreens in mice and warrant studies in humans to validate synergistic protection achievable by complementation of oral and topical sunscreen usage.[2]

Recent investigation demonstrated the skin cancer chemoprevention potential of 14 commonly used sunscreen agents using the Epstein-Barr virus early antigen (EBV-EA) activation assay. This short-term in vitro method utilizes the EBV genome carrying human lymphoblastoid Raji cells treated with tumor promoter TPA and assesses the tumor-inhibitory effect of sunscreens on EBV-EA activation at the promotional stage of cancer development. Among the sunscreens studied, those belonging to the benzophenone chemical group, octabenzone (UV-1), dioxybenzone (UV-2), oxybenzone (UV-3) and sulsibenzone (UV-13) showed significant chemopreventive activity with relative ranking of UV-2 >UV-3 >UV-1 > UV-13.The dihydroxy derivative of benzophenone (UV-2) exhibited higher chemopreventive potential than the three monohydroxy derivatives, Octabenzone, UV-3 and UV-13, which correlated with their antioxidant activity profile.

Effect of Ultraviolet Absorber Octabenzone on the Performance of SBS-Modified Asphalt

When using asphalt mixes, the process of ultraviolet radiation induced by asphalt UV aging cannot be neglected, since asphalt mixes are prone to aging under heat or natural conditions. According to relevant studies, the Octabenzone content that can improve the UV aging resistance of asphalt is in the range of 0.2% to 1.2%. Hence, the paper chose three Octabenzone doping levels—0.4%, 0.7%, and 1.0%. UV-531 was added to SBS-modified asphalt by melt blending. Needle penetration, softening point, and 5 °C ductility tests were chosen to assess the effect of UV-531 on the conventional properties of SBS-modified asphalt. UV aging of treated asphalt was performed using DSR and DMA tests to evaluate the effect of Octabenzone on the high- and low-temperature performance of SBS-modified asphalt. Finally, the optimum dose was derived after evaluating the Octabenzone/SBS-modified asphalt for UV aging resistance using rutting factor ratio, viscosity index, and infrared spectroscopy.[3]

Asphalt pavements at high altitudes are susceptible to aging and disease under prolonged action of UV light. To improve their anti-ultraviolet aging performance, Octabenzone/SBS-modified asphalts with UV-531 dopings of 0.4%, 0.7%, and 1.0% were prepared by the high-speed shear method, and the effect of Octabenzone on the conventional performance of SBS-modified asphalt before aging was studied by needle penetration, softening point and 5 °C ductility tests. The high- and low-temperature rheological properties of Octabenzone/SBS-modified asphalt before and after aging were also analyzed by high temperature dynamic shear rheology test and low-temperature glass transition temperature test. Finally, the effect of UV-531 on the anti-aging performance of SBS-modified asphalt was evaluated by three methods, including rutting factor ratio, viscosity aging index, and infrared spectroscopy. The results show that with the increase of Octabenzone doping, the needle penetration and 5 °C ductility show an increasing trend, but the effect on the softening point is small. 

The needle penetration, softening point, and 5 °C ductility of Octabenzone/SBS asphalt for the purpose of assessing the effect of UV-531 on the conventional properties of SBS-modified asphalt were measured. DSR and DMA tests were performed to estimate their effects on the high and low temperature properties of SBS-modified bitumen. Three methods were chosen to investigate the aging behavior of modified asphalt Octabenzone/SBS, such as rutting factor ratio, viscosity aging index, and infrared spectroscopy. In a comprehensive view, the addition of Octabenzone can enhance the UV aging resistance of asphalt effectively with an optimal dose of 0.7%. The main conclusions are listed below.

(1)The ductility at 5 °C and needle penetration of SBS-modified asphalt were improved with the increase of UV-531 addition, while the softening point was less affected. This means that the addition of Octabenzone improved the low temperature properties and viscosity of SBS-modified asphalt, while the high temperature properties were less affected. (2)The DSR test revealed that Octabenzone enhanced the high temperature rheological properties of SBS-modified asphalt to some degree. It was shown in the DMA test that the increase of UV-531 could reduce the glass transition temperature by a maximum of 54.74%, which led to a significant improvement in the low temperature anti-cracking properties of asphalt after ultraviolet light aging. (3)Three evaluation methods were selected to evaluate the aging. In the evaluation method based on the rutting coefficient ratio, the rutting coefficient ratio reduced as the amount of Octabenzone doping increased, demonstrating that Octabenzone inhibits UV aging. In the evaluation, a method based on viscosity aging index was used. As the viscosity before aging decreased with increasing dosing, the viscosity aging index also decreased, reaching a minimum at a dosing of 0.7%, indicating that UV-531 can increase the aromatic structure of asphalt. According to the analysis of the degree of aging by infrared spectra, the characteristic peaks of infrared spectra vary more obviously in the first, second and third regions, and the analysis results were that the UV aging degree of Octabenzone/SBS asphalt with 0.7% admixture was significantly lower than that of SBS-modified asphalt.

References

[1]JIANGSU ZIQI CHEMICAL TECH - CN112142581, 2020, A

[2]Rao GS, Tokuda H, Ichiishi E, Takasaki M, Iida A, Suzuki N, Konoshima T, Kapadia GJ. Oral chemoprevention of skin cancer in mice by benzophenone sunscreens dioxybenzone and octabenzone in drinking water. Anticancer Res. 2013 Jun;33(6):2535-40.

[3]Liu L, Liu L, Liu Z, Yang C, Pan B, Li W. Study on the Effect of Ultraviolet Absorber UV-531 on the Performance of SBS-Modified Asphalt. Materials (Basel). 2022 Nov 16;15(22):8110.

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