Intermediate chlorides, bromides and iodides exist. Alkyl iodides react the fastest, followed by alkyl bromides and then alkyl chlorides. Sodium iodide is used for conversion of alkyl chlorides into alkyl iodides. Analogous compounds are not formed with fluorides, bromides, iodides and cyanides. After addition of the acid, chlorides, bromides and iodides will form precipitates with silver nitrate. Examples of such medications include lithium, hydantoin, isoniazid, glucocorticoids, iodides, bromides, and testosterone. Bromides and iodides of rhenium are also well known. Normally, vinyl iodides and bromides are used. Bromides, iodides, and fluorides are also known but less important. Besides mercury vapor, the lamp contains iodides or bromides of different metals. Aniline combines directly with alkyl iodides to form secondary and tertiary amines. It also covers iodides, sulfides and similar simple salts of these metals. Rhodium iodides and lithium salts are employed as catalysts. Alkyl iodides are alkylating agents and contact should be avoided. Many of the iodides form soluble complexes with ethers, e.g. TmI(dimethoxyethane).