1-Bromonaphthalene is an organic compound with the formula C<sub>10</sub>H<sub>7</sub>Br. It is one of two isomeric bromonaphthalenes, the other being 2-bromonaphthalene. Under normal conditions, the substance is a colorless liquid.
It is prepared by treatment of naphthalene with bromine:
The compound exhibits many reactions typical of aryl bromides. Bromide can be displaced by cyanide to give the nitrile. It forms a Grignard reagent and organolithium compound. 1-Lithionaphthalene can be further lithiated to give 1,8-dilithionaphthalene, a precursor to peri-naphthalene compounds.
Because of its high refractive index (1.656-1.659<sub>nD</sub>), 1-bromonaphthalene is used as an embedding agent in microscopy and for determining the refraction of crystals.
The compound is also used as a precursor to various substituted derivatives of naphthalene.