Crystal Structures of a Series of Bis{(2-Aminobenzoyl-)amino}alkanes

Abstract  The crystal structures of 1,2-bis-{(2-aminobenzoyl-)amino}ethane(1), 1,4-bis-{(2-aminobenzoyl-)amino}butane(2) and 2,2-dimethyl-1,3-bis-{(2-aminobenzoyl-)amino}-propane(3) have been determined by single crystal X-ray diffraction analysis. 1 and 2 are centrosymmetric molecules which lie on crystallographic centers of symmetry and adopt extended conformations. On the other hand, owing to the odd number of carbon atoms in the spacer unit, 3 does not show centrosymmetry, but crystallizes in a non-centrosymmetric space group and assumes a folded conformation. The crystal structures of 1, 2 and 3 are compared with the known structures of anthranilamide (7) and the N-alkyl anthranilamide derivative 8. Crystal data: 1 C₁₆H₁₈N₄O₂, monoclinic, space group P2₁/a, a = 9.5262(8) ?, b = 5.4200(5) ?, c = 15.3821(14) ?, β = 105.980(5)° and V = 763.52(12) ?³, for Z = 2. 2 C₁₈H₂₂N₄O₂, monoclinic, space group C2/c, a = 32.0710(17) ?, b = 5.4732(4) ?, c = 9.7326(5) ?, β = 102.570(4)° and V = 1667.42(17) ?³, for Z = 4. 3 C₁₉H₂₄N₄O₂, orthorhombic, space group Pca2₁, a = 16.7676(4) ?, b = 10.1847(2) ?, c = 10.5338(5) ?, and V = 1798.89(7) ?³, for Z = 4. Index Abstract  The crystal structures of 1,2-bis-{(2-aminobenzoyl-)amino}ethane(1), 1,4-bis-{(2-aminobenzoyl-)amino}butane(2) and 2,2-dimethyl-1,3-bis-{(2-aminobenzoyl-)amino}-propane(3) have been determined by single crystal X-ray diffraction analysis. 1 and 2 are centrosymmetric molecules which lie on crystallographic centers of symmetry and adopt extended conformations, whereas 3 does not show centrosymmetry, but crystallizes in a non-centrosymmetric space group and assumes a folded conformation.      

Three-dimensional axisymmetric flow in perfectly plastic metals

A method is presented for solving the three-dimensional axisymmetric field equations for a perfectly plastic material which obeys the von-Mises yield criterion and the Levy-Mises flow law. The method is used for the particular case in which a small axisymmetric perturbed flow is superposed on a uniform flow without flow reversal taking place. The method then leads to solving a fourth order differential equation for the velocity potential. The special case of a thick cylindrical shell under compressive flow is examined. The solution so obtained, being derived, from the three dimensional theory, includes a correct treatment of transverse shear distortion. A preferred mode of instability is identified having a wave-length in reasonable agreement with that obtained experimentally by other workers.     

A novel transformation in the quadrone series

A remakable reaction of the substituted bicyclo [3,3,0] oct-3-ene-2-one ($\text{2e}$) with the sodium enolate of malonic ester is described.     

The perception and appreciation of richness and timbre in rooms for music

Musical reasons are given for imposing certain limits on the width of rooms for music and for designing so that first lateral reflections arrive at the listener within certain angles. The theory that timbre is partially conditioned by the angle of incidence of the first reflections is expounded. Musical subjective criteria are arranged in a personal order of preference, with an attempt at describing their physical counterpart. Performers' requirements are suggested in the light of recent measurements of the fluctuations in the frequency spectrum caused by the filtering of sound waves by the outer ear.