Ortho effects in organic molecules on electron impact: 21—Oxygen transfers from the ortho nitro group to sulphur in N-aryl-2-nitrobenzenesulphenamides and phenyl-2-nitrophenyl disulphide

Fragment ions arising as a result of oxygen transfers from the nitro group to sulphur have been noticed in N-aryl-2-nitrobenzenesulpbenamides and phenyl-2-nitrophenyl disulphide. In the case of the former a double oxygen transfer to the sulphur has been noticed in the molecular ion whilst a single oxygen transfer to the β-sulphur atom and a double oxygen transfer to the α-sulphur atom have been observed in the latter. The proposed fragmentations are confirmed by high-resolution data, B/E linked-scan spectra and chemical substitution.     

Synthesis of some novel annelated 1,2,3‐selena/thiadiazoles and 2h‐diazaphospholes

A number of annelated heterocyclic indene derivatives having 1,2,3‐selena/thiadiazole and 2H‐1,2,3‐diazaphosphole rings have been synthesized by exploiting the α‐ketomethylene functionality in some novel 1‐methyl‐piperidin‐4‐ones and 1‐oxo‐tetrahydrothiopyran‐4‐ones and were characterized by their physical and spectral data.     

Competing oxygen migrations in ortho nitro aromatic thioamides on electron impact

Interesting competitive oxygen migrations from the nitro group to the nitrogen and to the sulfur have been noticed during the mass spectral decomposition of ortho nitro aromatic thioamides on electron impact. The migration of the oxygen to the nitrogen of the thioamide function results in the formation of stable o-nitrosothiobenzoyl cation. The other novel ortho effect noticed in the ortho isomers is the transfer of an oxygen from the nitro group to the sulfur followed by the ejection of SO from the molecular ions. A mechanism involving the initial oxygen migration to the sulfur through a favourable 6-membered transition state followed by cyclization with the concomitant expulsion of SO is proposed for this process. Other interesting decomposition processes occurring as a consequence of this ortho effect have also been noticed. The proposed mechanisms for these processes are supported by mass analysed ion kinetic energy spectra and high voltage scans.     

Some studies on thallium oxalates. I. Thermal decomposition of ammonium bisoxalatothallate(III)

Trivalent thallium is precipitated in the presence of 0.1 M HNO₃ (or 0.05 M H₂SO₄) and O.1 M NH₄NO₃ (or 0.05 M (NH₄)₂SO₄) with oxalic acid. The chemical analysis of the salt obtained correspondens to the formula, NH₄[Tl(C₂O₄)₂]·3H₂O. The thermal decomposition studies of the complex indicate the formation of the intermediates ammonium thallous oxalate (stable from 150° to 160°C) and thallous oxalate (stable up to 290°C) and the final product to be a mixture of 25% of thallous oxide and 75% of thallic oxide (stable from 450° to 650°C). The infrared absorption spectra, X-ray diffraction patterns, microscopic observations and the electrical resistance measurements are used to characterise the complex and the intermediates of its thermal decomposition.     

Ortho effects in organic molecules on electron impact: 19—Competing oxygen transfers from nitro group to sulphur and acetylinic carbons in 2-nitrophenylphenylethynylsulphides

Oxygen transfers to both the acetylenic carbons and sulphur are noticed in parallel fragmentation pathways during the electron-impact induced decompositions of 2-nitrophenylphenylethynylsulphides. Single oxygen transfer to acetylinic carbons leads to the most abundant ion corresponding to the benzoyl cation whilst double oxygen transfers to both the acetylenic carbons followed by the ejection of two CO units from the M⁺˙ ion afford another abundant fragment corresponding to the phenothiazine radical cation. However, the oxygen transfers to sulphur yield a less abundant [M ? SO₂H]⁺ ion. The proposed fragmentation pathways and the ion structures are sup ported by high-resolution data, collision-induced dissociation Linked-scan spectra and chemical substitution.     

Combined forced and free convective flow of water at 4°C past a semi-infinite vertical plate

Effects of buoyancy forces on forced and free convective flow of water at 4°C past a semi-infinite vertical plate at constant temperature are studied. Flow is assumed to be vertically upwards. Similarity solutions are derived and the resulting equations are solved numerically on a computer. Velocity and temperature profiles are shown graphically and numerical values of the skin friction and the rate of heat transfer are entered in tables. It is observed that the skin friction and the Nusselt number increase with increasing Gr/Re², where Gr is the Grashof number and Re is the Reynolds number     

Nuclear spin-lattice and nuclear spin-spin relaxation time measurements in EuB6 at low temperatures using the spin-echo technique

Experimental results on the nuclear spin-lattice and nuclear spin-spin relaxation times in the ferromagnetic EuB₆ at temperatures below 4·2 K are presented using the external magnetic field,H _ext, in the range of 0 ⩽H _ext ⩽ 10 kG. Nuclear spin-spin relaxation time computed on the basis of the Suhl-Nakamura process turns out to be 3·2μs, which compares well with the experimental value 11·1μs obtained with the 10 kG magnetic field at 1·7 K. It is found that in the ferromagnetic EuB₆,T ₁ is approximately 5 × 10³ times larger thanT ₂ at 1·7 K with the 10 kG magnetic field. Thus the effect ofT ₁ onT ₂ can be neglected. From the experimental value ofT ₂, the value of the homogeneous line broadening is found to be 14 kHz. The corresponding value obtained from the cw method is 175 kHz. This evidently shows the presence of the inhomogeneous line broadening in the cw NMR.