Drometrizole

Preparation

First, p-toluenesulfonyl chloride was reacted with pyridine in the presence of sodium carbide to give N-p-toluenesulfonylpyridinone (1). Then, N-p-toluenesulfonylpyridinone (1) was condensed with p-hydroxybenzoic acid in the presence of zinc chloride to give the UV-P intermediate 2-(2-(p-toluenesulfonyl)-4-methoxyphenyl)-5-(2-hydroxyphenyl)-1,3,4-thiadiazole (2). Finally, the intermediate 2-(2-(p-toluenesulfonyl)-4-methoxyphenyl)-5-(2-hydroxyphenyl)-1,3,4-thiadiazole (2) was hydrolyzed in the presence of sodium hydroxide to give the final product 2-(2-(p-toluenesulfonyl)-4-hydroxyphenyl)-5-(2-hydroxyphenyl)-1,3,4-thiadiazole (UV-P).

Characterization

Drometrizole is an ultraviolet light absorber (UVA) of the hydroxyphenyl benzotriazole class, imparting good light stability to a wide variety of polymers.

Applications

Drometrizole provides ultraviolet protection in a wide variety of polymers including styrene homoand copolymers, engineering plastics such as polyesters and acrylic resins, polyvinyl chloride, and other halogen containing polymers and copolymers (e.g. vinylidenes), acetals and cellulose esters. Elastomers, adhesives, polycarbonate blends, polyurethanes, and some cellulose esters and epoxy materials also benefit from the use of Drometrizole.
   

Features/benefits

Drometrizole features a strong absorption of ultraviolet radiation in the 300-400 nm region. It also has a high degree of photostability over long periods of light exposure. The high absorbance combined with photostability and the ability to release absorbed energy in non sensitizing ways make Drometrizole an effective stabilizer against the effects of ultraviolet light.

Guidelines for use

The use levels of Drometrizole range between 0.10% and 0.50%, depending on substrate and performance requirements of the final application. Drometrizole can be used alone or in a variety of blends and combinations with Ciba IRGAFOS®, Ciba IRGANOX® and Ciba CHIMASSORB® stabilizers where often a synergistic performance is observed. Drometrizole may react with various heavy metal ions to form salts or complexes. For example, if Drometrizole comes into contact with iron or cobalt ions, colored complexes are formed. Reducing and oxidizing agents used in polymerization and curing processes have no effect on the stability of Drometrizole.

Physical Properties

Safety

In accordance with good industrial practice, handle with care and avoid unnecessary personal contact. Protect skin. Prevent contamination of the environment. Avoid dust formation and ignition sources.

Chemical Properties

Light yellow powder

Uses

Drometrizole is an intermediate reactant in the synthesis of UV light absorbers for polyester fibers.

Uses

An ultraviolet light absorber for stabilizing plastics and other organic materials against discoloration and deterioration.

Uses

2(2-Hydroxy-5-methylphenyl)benzotriazol is an UV adsorber for use in plastics, cosmetics, dental materials, acrylic materials, dyes, etc.

Definition

Drometrizole is a member of triazoles.

Application

Intermediate reactant in the synthesis of UV light absorbers for polyester fibers
Reactant for synthesis of:
Benzotriazole UV absorbers with a blocked hydroxy group for us in UV curable paint
Maleimide-bound benzotriazole monomer to use for emulsion polymerization
Used in:
Microstereophotolithography and shape memory alloy for fabrication of miniaturized actuators
PVS and wood / PVC composites as a stabilizer
Acrylonitrile-butadiene-styrene as a UV absorber.

Flammability and Explosibility

Not classified

reaction suitability

reaction type: C-C Bond Formation

Toxicity evaluation

The mutagenicity study of drometrizole was performed using Salmonella typhimurium strains TA1538 and TA98 with metabolic activation in the Ames’ test. Spot test (10 and 100 mg drometrizole/plate) and top agar method (50 and 100 mg drometrizole/plate) were conducted. The results showed that drometrizole was not mutagenic.Mice and rats were administered 5.0 or 10.0 g/kg of drometrizole in sunflower oil by stomach tube intubation. After body weight and behaviour were monitored for 3 weeks, acute toxicity of drometrizole was evaluated to be low. The oral lethal dose (LD50) of drometrizole in mice was reported to be 6.5 g/kg and > 5.0g/kg. Oral toxicity was evaluated in rats for nail care cosmetics containing 1%, 0.3% and 0.03% of drometrizole. The LD50 of products containing 1% of drometrizole was > 15.0 g/kg. The LD50 of products containing 0.3% and 0.03% drometrizole was > 5.0 g/kg. No acute toxicity was observed in these treatments.