Sodium iodide is used for conversion of alkyl chlorides into alkyl iodides. Aniline reacts with acyl chlorides such as acetyl chloride to give amides. It reacts with electrophilic chlorides including acyl chlorides, sulfur chlorides, and phosphorus chloride. After addition of the acid, chlorides, bromides and iodides will form precipitates with silver nitrate. Thionyl chloride converts phosphonic acids and phosphonates into phosphoryl chlorides. Concentrated hydrochloric acid dissolves many metals and forms oxidized metal chlorides and hydrogen gas. Thionyl chloride can be used to convert carboxylic acids to their corresponding acyl chlorides. The salt forms crystalline hydrates, unlike the other alkali metal chlorides. Since acyl chlorides and acid anhydrides also react with water, anhydrous conditions are preferred. Pollutants including sulfates, chlorides, and arsenic have been found in groundwater nearby. Aluminium nitride is resistant to attack from most molten salts, including chlorides and cryolite. The organotin hydrides are generated by reduction of the mixed alkyl chlorides. CHC(O)Cl by treatment with thionyl chloride, phosgene or one of the chlorides of phosphorus. Brass will corrode in the presence of moisture, chlorides, acetates, ammonia, and certain acids.