Isopropyl chloride (also chlorodimethylmethane, 2-propyl chloride, sec-propyl chloride or 2-chloropropane) is a colorless, flammable chemical compound . It has the chemical formula C3H7Cl and is prepared by refluxing isopropyl alcohol with concentrated hydrochloric acid and zinc chloride.
Structurally, isopropyl chloride is an organochlorine compound as well as a secondary (2°) haloalkane, the latter designation identifying the two C-C bonds seen around the carbon atom covalently bonded with the chlorine substituent. To compare, its structural isomer, 1-chloropropane, is instead an example of a primary (1°) haloalkane, as the chlorine-bound carbon atom has only one C-C bond.
Haloalkanes generally resemble the parent alkanes in being colorless, relatively odorless, and hydrophobic substances. A significant difference is that their boiling points are higher than the corresponding alkanes and scale with atomic weight and number of halides. This effect is due to the increased strength of the molecules intermolecular forces—from London dispersion forces to dipole-dipole interactions created with the increased polarity. As the chlorine atom produces increased intermolecular attractions, 2-chloropropane is encountered in a liquid state at STP while propane is gaseous.
Due to fewer C–H bonds haloalkanes are less flammable than alkanes which makes some useful ingredients in fire extinguishers - isopropyl chloride is quite flammable however. Further, haloalkanes are better solvents than the corresponding alkanes because of their increased polarity, and those containing halogens other than fluorine are also more reactive than the parent alkanes.
As a laboratory reactant, heating 2-chloropropane with alcoholic potassium hydroxide will yield propene (an alkene) by a dehydrohalogenation reaction. However, reacting with potassium hydroxide would compete with an Sn2 nucleophilic substitution reaction (minor product) because OH- is a strong, sterically unhindered nucleophile. Because of this, potassium tert-butoxide is one example of a better reagent to use.