It photooxidizes in air to benzophenone and sulfur. A similar process based on benzophenone has also been described. It is prepared by heating tetraphenylcyclopentadienone and diphenylacetylene in benzophenone or other high-temperature solvent. However, this reaction is unsuccessful with less electrophilic ketones, such as acetone and benzophenone. The high-strength polymer PEEK is prepared from derivatives of benzophenone. Benzophenone derivatives are known to be pharmacologically active. Acetone and benzophenone (CHC(O)CH) are symmetrical ketones. The decomposition can be effected by photolysis, photosensitized reagents (such as benzophenone), or thermal decomposition. Benzophenone is a common photosensitizer in photochemistry. The advantage of using sodium/benzophenone is that moisture and oxygen are removed as well. Another, less well-known reaction to produce benzophenone is the pyrolysis of anhydrous calcium benzoate. A chemical pure-grade ammonia gas is added to a benzophenone solution, forming PhC=NH. Benzophenone imine is an organic compound with the formula of (CH)C=NH. Benzophenone is often used to generate such a soluble drying agent. Benzophenone is an endocrine disruptor capable of binding to the pregnane X receptor.