2-[(4-Bromobenzylidene)amino]ethanol

In the crystal structure of the title compound, C9H10BrNO, molecules are linked via O—H⋯N hydrogen bonds of a moderate strength between the hydroxy groups and the imine N atoms. These hydrogen bonds, as well as the planes of the bromophenyl rings, are situated in alternating planes parallel to (013) and (0-13). In addition, there are weak C—H⋯π interactions in the structure.

In the crystal structure of the title compound, C 9 H 10 BrNO, molecules are linked via O-HÁ Á ÁN hydrogen bonds of a moderate strength between the hydroxy groups and the imine N atoms. These hydrogen bonds, as well as the planes of the bromophenyl rings, are situated in alternating planes parallel to (013) and (013). In addition, there are weak C-HÁ Á Á interactions in the structure.
Data collection: APEX2 (Bruker, 2006); cell refinement: SAINT (Bruker, 2006); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008b); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008b); molecular graphics: ORTEP-3 (Farrugia, 2012); software used to prepare material for publication: SHELXL97. The title compound, 2-(4-bromobenzylideneamino)ethanol, was prepared and crystallized during our ongoing research on nitrogen-based ligands (Williams et al., 2007). The molecule belongs to the class of compounds known as the Schiff bases (Tidwell, 2007). The primary feature of all the Schiff bases is presence of a functional group that includes a carbonnitrogen double bond, known as the imine group. The imine's nitrogen atom can be connected to a hydrogen atom, or aryl or alkyl groups (Jafarpour et al., 2011). In cases where the hydrogen atom is bonded to the nitrogen atom, i. e. RCH═NH, the imine is an unstable chemical species (an intermediate) because it is prone to decomposition (through reaction with oxygen or moisture in air). This intermediate is formed during the reaction between an aldehyde and ammonia that leads to direct conversion into the amine product by a process called reductive amination (Morrison et al., 1987). In cases where an aryl-or alkyl group (as is the case in the present study) is bonded to the nitrogen atom, i. e. R C═NR, the imine shows a significant improvement in stability and the compound can be isolated. In the present study, the alkyl group with a stabilizing effect (specifically, an ethyl group) is bonded to the nitrogen atom while the ethyl group also contains a hydroxyl moiety.
The Schiff bases have a number of useful applications such as their use as ligands in coordination chemistry and their role in forming supramolecular metallocycles and metallocages. In addition, the aryl Schiff bases, such as the title compound, are also commonly synthesized for pharmaceutical objectives or used in the synthesis of biologically useful compounds. These biological compounds include a range of applications in anti-fungal, anti-inflammatory, anti-HIV, antibacterial, herbicidal, and anti-cancer activities (Khan et al., 2009;Gerdemann et al., 2002;Samadhiya & Halve, 2001;Mallikarjun & Sangamesh, 1997;Fioravanti et al., 1995;Solomon & Lowery, 1993).
As a result of importance of the Schiff bases outlined above, new synthesis methods are being developed in order to obtain better yields at lower cost (Veverková & Toma, 2008).
The most commonly used procedure for the synthesis of the Schiff base compounds involves condensation of an amine with an aldehyde (Elslager et al., 1956). This was also the procedure that we have used in the present study. We have synthesized the title molecule with goal to use it as a ligand in metal complexation. As a result, we wanted to discover its 3-dimensional spatial arrangement in the solid-state so that we can determine whether appropriate binding sites through donor N and O atoms on the title compound has the potential to bind to a metal center. This hypothesis needs to be tested with future experimentation.
The basic structural features of the title structure ( Fig. 1) agrees well with the geometric parameters of similar previously synthesized structures such as (E)-4-[(4-bromobenzylidene)amino]-phenol (Vennila et al., 2010). The C-Br bond distance in the title compound is 1.900 (3) Å, which is in agreement with the related value of 1.894 (2) Å (Vennila et al., 2010). The packing of the molecules is shown in Figs. 2 and 3. Fig 3 shows the O-H···N hydrogen bonds of a moderate strength (Gilli & Gilli, 2009;  the planes of the bromophenyl rings are situated in alternating planes parallel to (0 1 3) and (0 -1 3). In addition, there are weak C-H···π-electron ring interactions in the structure (Table 1).

Experimental
To a solution of 4-bromobenzaldehyde (2.031 g, 0.011 mol) in dry toluene (40 ml), ethanolamine (0.671 g, 0.011 mol), also dissolved in dry toluene (40 ml), was added dropwise in intervals of 30 minutes while stirring the formed suspension. The reaction mixture was stirred under ambient conditions for further 2 hrs, and then refluxed at 120 °C for 3 hrs. The water was removed by distillation in a Dean-Stark distillation receiver and the toluene was removed in vacuo.
Upon cooling of the reaction mixture, the material precipitated. The viscous matter was dissolved in 20 ml of dichloromethane. The solution was then filtered through Celite (diatomaceous earth, a filter-aid) and dried over anhydrous

Refinement
The hydrogen atoms were identified in the difference electron density map, after which the aryl and methyl H atoms were situated into idealized positions and constrained to ride on their parent atoms, with C···H = 0.95 and 0.98 Å, respectively.
U iso (H aryl ) = 1.2×U eq C aryl and U iso (H methyl ) = 1.5×U eq C methyl . The methyl groups were refined as rigid rotors in order to fit to the electron density. The positional parameters of the primary and the secondary amine H atoms were freely refined while their displacement parameters were constrained as 1.2 multiples of their carrier atoms. 788 Friedel pairs have been measured.

Figure 1
The molecule with the atom labelling scheme. The displacement ellipsoids are shown the 50% probability level.  The crystal packing of the title compound as seen approximately along the b axis.

Figure 3
The crystal structure of the title compound with the hydrogen bonds (Tab. 1) indicated as dashed lines. The structure is approximately viewed along the c axis. Symmetry code: (i) x, -y + 1, z + 1/2. Refinement. 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 > σ(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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å 2 )
x y z U iso */U eq