8-Bromonaphthalen-1-amine

The title compound, C10H8BrN, was obtained by slow addition of sodium azide to 8-bromo-1-naphthoic acid, followed by addition of aqueous ammonia. The crude product was crystallized from petroleum ether to give pink crystals. Compared to other 1,8-disubstituted naphthalene compounds, this compound exhibits less strain between the 1 and 8 substituents. Additionally, the NH protons form both intra- and intermolecular hydrogen bonds. The naphthalene units are arranged in a herring-bone stacking motif.


Experimental
Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: SI2087).
hydrogen bonding interaction between the N1-H1a···Br1 enables a close nonbonding Br1···N1 distance and at the same time leaves the molecule relatively unstrained.
The other NH proton is involved in the intermolecular hydrogen bond (Table 1)

Experimental
The title compound was prepared by a method previously described (Herbert et al., 1987). Sodium azide (3.10 g, 0.048 mol) was added over a 10 minute period to a stirred suspension of 8-bromo-1-naphthoic acid (2.0 g, 0.008 mol) in concentrated sulfuric acid (7 ml) and chloroform (7 ml) at 45° C. Each successive portion of sodium azide being added after the effervescence resulting from the previous addition had subsided. The mixture was stirred for 90 minutes at 45°C and added to water (140 ml), and it was made alkaline with aqueous ammonia and extracted with chloroform (3 x 140 ml). The combined extracts were dried with magnesium sulfate and evaporated to give the desired product. Yield 1.30 g (73%). The black crude product was recrystallized from 60-80 petroleum ether to give pink crystals.

Refinement
C7 was refined subject to an ISOR constraint. All H atoms were included in calculated positions (C-H distances are 0.95 Å, N-H distances are 0.98 Å) and were refined as riding atoms with U iso (H) = 1.2 U eq (parent carbon atom) The N-H protons were refined subject to a distance constraint but with a riding thermal parameter.
Refinement of F 2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F 2 , conventional R-factors R are based on F, with F set to zero for negative F 2 . The threshold expression of F 2 > 2sigma(F 2 ) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F 2 are statistically about twice as large as those based on F, and R-factors based on ALL data will be even larger.
supplementary materials sup-2 Figures   Fig. 1. The structure of the title compound with labelled atoms and with displacement ellipsoids for non-H atoms drawn at the 50% probability level. The intramolecular hydrogen bond is indicated by a dashed line.