Aspects of tautomerism. Part 16. Influence of the y-keto function on the reactions of sulphonic acids

Reaction of sodium 2-formylbenzenesulphonate (1) with thionyl chloride or phosphorous pentachloride gives a mixture of pseudo (2) and normal (3) sulphonyl chlorides. Whereas ammonium 2-carboxybenzenesulphonate (6) gives only the normal sulphonyl chloride (7) on reaction with thionyl chloride, a mixture of normal (7) and pseudo (8) isomers are formed on reaction with phosphorous pentachloride. Sodium 2-benzoylbenzenesulphonate (15), on the other hand, gives the corresponding normal sulphonyl chloride (16) on reaction with both of the reagents mentioned above. Based on these observations it is concluded that γ-keto sulphonic acids are amenable to the influence of γ-carbonyl group as in the case of γ-keto carboxylic acids but to a lesser extent.     

Investigations into the nitric acid mediated dehalonitration of halophenols

A reaction of nitric acid with bromophenols and iodophenols results in substitution of the halogen with a nitro group. The study indicates moderate reactivity for bromophenols and iodophenols, while chlorophenols were found to be sluggish in this reaction.     

Alicyclic-Amine-Derived Imine-BF3 Complexes: Easy-to-Make Building Blocks for the Synthesis of Valuable α-Functionalized Azacycles

A new strategy to access α-functionalized alicyclic amines via their corresponding imine-BF₃ complexes is reported. Isolable imine-BF₃ complexes, readily prepared via dehydrohalogenation of N-bromoamines in a base-promoted/18-crown-6 catalyzed process followed by addition of boron trifluoride etherate, undergo reactions with a wide range of organometallic nucleophiles to afford α-functionalized azacycles. Organozinc and organomagnesium nucleophiles add at ambient temperatures, obviating the need for cryogenic conditions. In situ preparation of imine-BF₃ complexes provides access to α-functionalized morpholines and piperazines directly from their parent amines in a single operation. α-Functionalized morpholines can be elaborated further, for instance by installing a second substituent in the α′-position.     

Shape of thermal etch pits and crystal structure in tellurium crystals

During the systematic study of thermal etching of tellurium crystals, various shaped thermal etch pits were observed on the {101 0} cleavage faces of this crystal. An attempt has been made to explain the shape of non-dislocation and dislocation etch pits. A simple model based on crystal structure and bonding of atoms has been suggested to explain the shape of etch pits.     

On hiding messages in the oversampled Fourier coefficients

A system using an oversampled Fourier transform for hiding data is given in [J.R. Miotke, L. Rebollo-Neira, Oversampling of Fourier coefficients for hiding messages, Appl. Comput. Harmon. Anal. 16 (2004) 203-207]. When viewed as a cryptographic algorithm, we demonstrate here that the system is susceptible to a known plaintext attack.     

Investigations of the first order magnetic phase transition in dysprosium

The first order magnetic phase transition in polycrystalline sample of dysprosium (Dy) has been investigated in detail by dc-resistance vs. temperature (R-T) measurements. Distinct signature of coexistence of two magnetically ordered phases (i.e. ferromagnetic and antiferromagnetic), originating as a result of the metastable behavior associated with the first order phase transition (FOPT) is found near 90 K. By successfully recording the minor hysteresis loops within the hysteretic R-T regime of Dy, a varying degree of phase coexistence in the FOPT is demonstrated.     

Saccharin as a salt former. Enhanced solubilities of saccharinates of active pharmaceutical ingredients

Saccharin, acting as a weak acid, forms salts with basic APIs and these salts have the desirable property of enhanced water solubility.