4-(4-Nitrophenoxy)biphenyl

The two phenyl rings of the biphenyl unit of the title compound, C18H13NO3, are almost coplanar [dihedral angle 6.70 (9)°]. The nitrophenyl ring, on the other hand, is significantly twisted out of the plane of the these two rings, making dihedral angles of 68.83 (4)° with the middle ring and 62.86 (4)° with the end ring. The nitro group is twisted by 12.1 (2)° out of the plane of the phenyl ring to which it is attached.

The two phenyl rings of the biphenyl unit of the title compound, C 18 H 13 NO 3 , are almost coplanar [dihedral angle 6.70 (9) ]. The nitrophenyl ring, on the other hand, is significantly twisted out of the plane of the these two rings, making dihedral angles of 68.83 (4) with the middle ring and 62.86 (4) with the end ring. The nitro group is twisted by 12.1 (2) out of the plane of the phenyl ring to which it is attached.

Related literature
The title compound is a precursor of amine which is a useful curing agent of epoxy resins. For the properties and applications of epoxy resins, see: Boey & Yap (2001); Bonnaud et al.  supporting information Acta Cryst. (2009). E65, o710 [doi:10.1107

S1. Comment
Epoxy resins are a versatile group of crosslinked polymers that has excellent chemical resistance, good electrical insulating properties, good adhesion to glass and metal and can be easily fabricated (Boey & Yap, 2001). Variety of properties helps epoxy resins to meet performance requirements of some demanding applications (Bonnaud et al., 2004).
These include areas as diverse as construction, electronics, adhesives and coatings (de Moris et al., 2007). The usefulness of epoxy resins is often limited due to their inherent brittleness arising from crosslinking structure (van de Grampel et al., 2005). Development of approaches for toughening epoxy resins without sacrificing modulus and glass transition temperature (Tg) would lead to an increase in their applications (Kagathera & Parsania, 2001). One such approach is the curing of epoxy resins with different curing agents (Agag & Takeichi, 1999). The title compound is a precursor of amine which is a useful curing agent of epoxy resins.
The two phenyl rings of the biphenyl moiety of the title compound are almost coplanar [dihedral angle 6.70 (9)°]. The nitrophenyl ring, on the other hand, is significantly twisted out of the plane of the these two rings [68.83 (4)° and 62.86 (4)°]. The nitro group is twisted by 12.1 (2)° out of the plane of the phenyl ring to which it is attached.

S2. Experimental
A 500 ml two neck round bottom flask was equipped with condenser and thermometer and was charged with (0.059 moles) biphenyl-4-ol, (0.059 moles) anhydrous potassium carbonate and (0.059 moles) 4-chloronitrobenzene in 180 ml of DMF. Reaction mixture was heated for 24 h at 120°C. The reaction was carried out in the inert atmosphere of nitrogen.
Progress of reaction was measured by TLC [1:1, ethyl acetae, n-hexane]. After completion, the reaction mixture was poured into 600 ml of water to give yellow precipitates. These precipitates were collected by filtration and washed with water several times. Recrystallization of the residue in n-hexane afforded the title compound (86%) (m.p 142-144°C)  Perspective view of the title compound with the atom numbering scheme; displacement ellipsoids are at the 50% probability level.

Figure 2
Packing of the title compound with view onto the ac plane, hydrogen atoms are omitted for clarity.

Special details
Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes. 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.