The X‐ray diffraction of molecular compounds of 2‐aminopyridine with long chain saturated and unsaturated fatty acids

X‐Ray diffraction measurements of long and short spacings are reported for the crystalline 1:1 and 4:1 molecular compounds of 2‐aminopyridine with the C 10 to C 18 saturated fatty acids and the 1:1 and 2:1 compounds of oleic, elaidic, alpha‐eleostearic and beta‐eleostearic acids. Data are also reported for 2‐aminopyridine, α‐eleostearic acid and β‐eleostearic acid. The angle of tilt of the 1:1 saturated compounds is 42°15′. The long spacings of the 4:1 compounds indicate a unit cell length of four molecules of fatty acid and one molecule of 2‐aminopyridine with an angle of tilt of 62°15′. The contribution of the 2‐aminopyridine to the length of a molecule of the 1:1 compounds is ca. 6 Å, the distance between the NH 2 and the CH 2 in the para position. In the 4:1 and 2:1 compounds it is ca. 3 Å, the distance between the NH 2 and the ring nitrogen.