1,3-Bis(propan-2-yl)naphthalene

In the title compound, C16H20, one of the isopropyl groups shows almost equal displacements [1.252 (1) and −1.270 (1) Å] of its methyl-C atoms from the mean plane of the naphthalene ring system, while the other shows asymmetric displacements [1.586 (2) and −0.315 (1) Å]. In the crystal, the molecules are linked into sheets lying in the ab plane by three C—H⋯π contacts, two involving donors belonging to the isopropyl groups and the third a donor atom from the naphthalene ring system. The different orientations of the isopropyl groups might be attributed to the fact that the C—H⋯π interaction involving one of them is enhanced by the C—H⋯π interaction involving the aromatic ring.

In the title compound, C 16 H 20 , one of the isopropyl groups shows almost equal displacements [1.252 (1) and À1.270 (1) Å ] of its methyl-C atoms from the mean plane of the naphthalene ring system, while the other shows asymmetric displacements [1.586 (2) and À0.315 (1) Å ]. In the crystal, the molecules are linked into sheets lying in the ab plane by three C-HÁ Á Á contacts, two involving donors belonging to the isopropyl groups and the third a donor atom from the naphthalene ring system. The different orientations of the isopropyl groups might be attributed to the fact that the C-HÁ Á Á interaction involving one of them is enhanced by the C-HÁ Á Á interaction involving the aromatic ring.
1,3-Bis(propan-2-yl)naphthalene B. Schröder, L. R. Gomes and J. N. Low Comment Alkylated naphthalenes have a wide spectrum of applications, ranging from solvents, insulating material, heat transfer fluids, dye works auxiliary and specialty lubricants, (Collin et al., 2003). Due to a variety of novel applications, diisopropylnaphthalene isomers have recently become of interest; they are used in the food packaging industry and as a plant growth regulator; furthermore, they have been introduced as PCB replacement fluids, (Addison,1983). The application of diisopropylnaphthalene isomer mixtures as solvents for carbonless copy paper, in its formulation known as KMC -Kureha Micro Capsule Oil -is of special importance. Some aromatic surfactants are partially based on propylated naphthalenes whose isomeric mixtures are used as water repelling agents for a variety of applications, such as corrosion protections, marine paints, resins,inks, coatings, plasticizers, or electrical, electronic and mechanical applications.
The main components of diisopropylnaphthalene isomer mixtures are 2,6-diisopropylnaphthalene and 2,7-diisopropylnaphthalene, contributing each with ca 40% to the mixture, while a few percent are made of the 1,3-, 1,6-and 1,7-diisopropylnaphthalenes, (Brzozowski et al., 2001). Diisopropylnaphthalenes with isopropyl groups positioned in adjacent ring positions are usually not detected in the mixtures. Separating all isomers or synthesizing them in pure form remains a challenging task.
The 1,3-isomer (I) is shown in Figure 1. The isopropyl methyl groups are oriented cis with respect to atom C2. The naphthalene-isopropyl torsion angles show that the orientations of the isopropyl groups around the C1-C11 and C3-C31 bonds with respect to the naphthalene ring is different in each case, e.g. C2-C1-C11-C111/C112 -23.24 (17)°/100.54 (14)° and C2-C3-C31-C311/C312 64.27 (16)°/-60.14 (15)°. The orientation of the isopropyl group attached to C1 is unexpected in that unlike the group attached to C3 in which the hydrogen atom attached to C31 lies in the plane of the plane of the naphthalene ring that attached to C11 does not do so.
These orientations position the hydrogen atoms attached to C11 and C31 so that the molecules are linked by three C-H···π contacts to form a sheet lying in the ab plane, Table 1 Fig. 1. A view of (I) with displacement ellipsoids drawn at the 30% probability level.  as those based on F, and R-factors based on ALL data will be even larger.