Thermal analysis of salts from 4-nitrophenol and aliphatic amines

In this work, the thermodynamic performance of a single slope solar still with cotton cloth energy storage medium was compared with a simple solar still without energy storage. Two solar stills with similar dimensions (one with cotton cloth energy storage and another without energy storage) were fabricated and investigated its performance under the hot humid climatic conditions of Chennai in India during the summer months of 2017. The performance was evaluated in terms of energy and exergy analysis based on first and second law of thermodynamics, respectively, for 2 mm, 4 mm, 6 mm and 8 mm cotton cloth thickness. The results showed that the maximum energy and exergy efficiency of a solar still was observed to be 23.8% and 2.6%, respectively, for 6 mm cotton cloth thickness. The results confirmed that the cotton cloth regenerative medium has enhanced the still productivity by about 24.1% when compared to the solar still without heat storage.

     

Selective n,n-dibenzylation of primary aliphatic amines with dibenzyl carbonate in the presence of phosphonium salts

In the presence of catalytic amounts of tetraalkylphosphonium salts and under solventless conditions, primary aliphatic amines (RNH(2): R = PhCH(2), Ph(CH(2))(2), n-decyl, and 1-naphthylmethyl) are efficiently N-benzylated to the corresponding RN(CH(2)Ph)(2), using dibenzyl carbonate as the benzylating reagent. Compared to the reaction run without salt, where the competitive formation of the benzyl carbamate is favored, the phosphonium salt promotes high selectivity toward the benzylated amine and an increase of the reaction rate as well. However, in a single case explored for an amino acidic compound, namely 4-(aminomethyl)benzoic acid [4-(NH(2)CH(2))C(6)H(4)CO(2)H], both N,N-dibenzylation and esterification of the acid group were observed. Analysis of the IR vibrational modes of benzylamine in the presence of tetrabutylphosphonium bromide supports the hypothesis that this enhanced selectivity may be due to an acid-base interaction between the salt and the amine, which increases the steric bulk of the amine and favors attack of the nucleophile on the less hindered alkyl terminus of dibenzyl carbonate.     

Thermodynamic characteristics of the behaviour of higher aliphatic amines on selected cellulose sorbents

Thermodynamic characteristics of the behaviour of higher aliphatic amines on chromatographic paper and cellulose powder are presented. A new method is described aiming to eliminate systematic error, connected with the visualization of the chromatographic spots on the investigated sorbents.     

Associative model of activation of diacyl peroxides by chloride salts of amines

Intermolecular and ion-molecule interactions of benzoyl peroxide with tetraethylammonium chloride in an acetonitrile medium have been investigated by means of NMR. The types of association of the diacyl peroxide with ammonium chloride have been modeled by means of the MNDO method. The state of the peroxide molecule in the associate has been analyzed.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 28, No. 4, pp. 320–323, July–August, 1992.     

Dehydrocondensation of triorganosilanes with piperazine and some aliphatic amines in the presence of potassium metal

Reaction of CH₃(C₆H₅)₂SiH with C₄H₉NH₂ in the presence of potassium metal gives, instead of the expected CH₃(C₆H₅)₂SiNHC₄H₉, benzene, diphenyl, and what is apparently a hitherto unknown substituted cyclodisolazane. The Si-C₆H₅ bond is broken not only by alkali metals, but also by their amides. For the case of piperazine it is shown that heterocyclic diamines react considerably more readily with trialkylsilanes than do aliphatic secondary amines.     

Copper(II)-catalyzed ether synthesis from aliphatic alcohols and potassium organotrifluoroborate salts

[reaction: see text] A protocol for the copper(II)-catalyzed etherification of aliphatic alcohols under mild and essentially neutral conditions is described. Air- and moisture-stable potassium alkenyl- and aryltrifluoroborate salts undergo cross-coupling with a variety of aliphatic primary and secondary alcohols and phenols, and are tolerant of a range of functional groups. The optimized conditions utilize catalytic copper(II) acetate with 4-(dimethylamino)pyridine as ligand in the presence of 4 A molecular sieves under an atmosphere of oxygen.     

Fluorescence decay of tertiary aliphatic amines

The fluorescence decay of the tertiary aliphatic animes trimethylamine (TMA), triethylamine (TEA) and tri-n-propylamine (TPA) in the vapour phase excited between 260 and 215 nm has been shown to consist of a single, wavelength-dependent, component when the first excited state is uniquely excited, but two components when the first and second excited states are simultaneously excited. This dual exponentiality persists at pressures as low as 10 mTorr, and it is argued that the two-component decay does not arise from collisional vibrational relaxation.     

Reaction of succinonitrile with aliphatic amines

Conclusions The reaction of primary amines with succinonitrile leads to the formation of N,N,N,N-tetrasubstituted amidines and the liberation of 2 M of NH₃. The reaction of secondary amines with succinonitrile proceeds as an intramolecular condensation with the liberation of 1 M of NH₃ per mole of the dinitrile and the formation of the ^2,5–, -dialkylaminopyrrolene.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 12, pp. 2722–2725, December, 1973.     

Influence of cation structure on decomposition of diacyl peroxides activated by chloride salts of amines

A kinetic study has been made of the interaction of benzoyl peroxide with a number of chloride salts of amines. It is shown that a change of the cation in quaternary ammonium salts does not have any significant effect on the kinetic parameters of the reaction. By means of NMR spectroscopy it has been determined that the structure of the NR₄ ⁺ cation does not change during the course of the reaction. The role of the cation in the process of activation of a diacyl peroxide by chloride salts of amines has been investigated by means of MNDO calculations.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 28, No. 4, pp. 324–328, July–August, 1992.     

Frovatriptan salts of aliphatic carboxylic acids

The interaction of the antimigraine pharmaceutical agent frovatriptan with acetic acid and succinic acid yields the salts (±)‐6‐carbamoyl‐N‐methyl‐2,3,4,9‐tetrahydro‐1H‐carbazol‐3‐aminium acetate, C₁₄H₁₈N₃O⁺·C₂H₃O₂⁻, (I), (R)‐(+)‐6‐carbamoyl‐N‐methyl‐2,3,4,9‐tetrahydro‐1H‐carbazol‐3‐aminium 3‐carboxypropanoate monohydrate, C₁₄H₁₈N₃O⁺·C₄H₅O₄⁻·H₂O, (II), and bis[(R)‐(+)‐6‐carbamoyl‐N‐methyl‐2,3,4,9‐tetrahydro‐1H‐carbazol‐3‐aminium] succinate trihydrate, 2C₁₄H₁₈N₃O⁺·C₄H₄O₄²⁻·3H₂O, (III). The methylazaniumyl substitutent is oriented differently in all three structures. Additionally, the amide group in (I) is in a different orientation. All the salts form three‐dimensional hydrogen‐bonded structures. In (I), the cations form head‐to‐head hydrogen‐bonded amide–amide catemers through N—H...O interactions, while in (II) and (III) the cations form head‐to‐head amide–amide dimers. The cation catemers in (I) are extended into a three‐dimensional network through further interactions with acetate anion acceptors. The presence of succinate anions and water molecules in (II) and (III) primarily governs the three‐dimensional network through water‐bridged cation–anion associations via O—H...O and N—H...O hydrogen bonds. The structures reported here shed some light on the possible mode of noncovalent interactions in the aggregation and interaction patterns of drug molecule adducts.     

Determination of higher aliphatic amines and cyclohexylamine by TLC after derivatization with 1-fluoro-2,4-dinitrobenzene

Summary Higher aliphatic amines and cyclohexylamine find use on a large scale as inhibitors of corrosion in power stations and in installations for drawing and storing natural gas in underground containers. The determination of active constituents of the inhibitors at the individual technological steps, very important for assessing the efficacy of the anticorosive protection, is complicated by other compounds accompanying the trace amounts of the amines being monitored. This circumstance makes it necessary to use selective methods based on the derivatization of the primary amino group and formation of intensively UV-VIS absorbing or fluorescent derivatives.These demands are met by the detection with ninhydrine [1, 2] or TLC of 2,4-dinitrophenyl-[3,4] or 3,5-dinitrobenzoyl-[5] amine derivatives. We applied a modified derivatization procedure with 1-fluoro-2,4-dinitrobenzene as UV label [6], well known as Sanger's reagent originally developed for the labeling of amino acids and peptides [7]. This reagent forms with amines intensively absorbing N-alkyl-2,4-dinitroaniline derivatives which can be easily separated by TLC.