Proton Affinities Of Amines Research Articles

Mass Spectrometric Investigation of Noncovalent Complexation between a Tetratosylated Resorcarene and Alkyl Ammonium Ions

Noncovalent complexation between tetratosylated tetraethyl resorcarene (1) and primary, secondary, and tertiary alkyl ammonium ions (mMe, dMe, tMe, mEt, dEt, tEt, dBu, and dHex) was studied by electrospray ionization Fourier transform ion cyclotron resonance (ESI-FTICR) mass spectrometry. Interactions of the noncovalent complexes were investigated by means of competition experiments, collision-induced dissociation (CID) experiments, ion-molecule reactions with tripropylamine and gas phase H/D-exchange reactions with deuteroammonia. Gas phase ion-molecule reactions gave especially valuable information about the structure and properties of the complexes. Resorcarene 1 formed relatively stable 1:1 complexes with all aliphatic alkyl ammonium ions. Steric properties of the alkyl ammonium ions and proton affinities of the conjugate amines noticeably affected the complexation properties, indicating the importance of hydrogen bonding in these complexes. According to the competition experiments, the thermodynamically most stable host-guest complexes were formed with alkyl ammonium ions that were most substituted and had the longest alkyl chains. In CID experiments, release of an intact free guest ion or dissociation of the host was observed to depend on the proton affinity of the amine and the strength of the hydrogen bond that was formed. In ion-molecule reactions with tripropylamine, a guest exchange reaction occurred with all alkyl ammonium ion complexes with reaction rates mostly dependent on the steric properties of the original guest ion. In H/D-exchange reactions the N-H hydrogen atoms of the guest ion were exchanged with deuterium, whereas the resorcinol hydrogen atoms remained unchanged.

Thermal features and thermochemistry of hexachlorozirconates of aliphatic and aromatic mono-amines—stability of hexahalogenozirconates

Thermal behaviour of the hexachlorozirconates of several alkanamines and aromatic mono-amines was examined using dynamic and quasi-isothermal-isobaric thermoanalytical methods. Decomposition of the compounds upon an increase in temperature is accompanied by partial volatilization. The residue contains ZrO 2 and is sometimes contaminated with traces of carbonization products. It is believed that the primary process, which can be summarized with the equation (where A denotes an alkyl or aryl substituent ( p=1–4; a=0 and s=1 for quaternary, and a=1 and s=0 for other compounds studied)) is followed by instantaneous oxidation of zirconium tetrachloride remaining in the condensed phase (cond). An insight into the thermodynamics of the compounds became possible on employing the van't Hoff equation to the non-isothermal thermogravimetric curves. This enabled evaluation of the enthalpies of the thermal decomposition and consequently the enthalpies of formation and the crystal lattice energies of the salts. The latter quantity was further examined using the Kapustinskii-Yatsimirskii method. Geometries, energies and other physicochemical properties of simple aliphatic and aromatic amines and their protonated forms were determined by AM1 and PM3 methods in order to reveal which of these correlate with the proton affinity of amines and the thermal behaviour and thermochemical characteristics of hexachlorozirconates. In addition, the influence of dimensions of ions on the thermodynamic stability of hexahalogenozirconates, with respect to dissociation and oxidation processes, was studied.

Gas phase (CH 3) 3Si + affinities of alkylamines and proton affinities of trimethylsilyl alkyl amines

The association reactions of (CH 3) 3Si + with primary, secondary and tertiary alkyl amines have been studied using a high pressure mass spectrometer with pulsed electron beam. Standard enthalpy and entropy changes have been measured for (CH 3) 3Si + transfer between amines and between some amines and a reference base, ethyl benzoate. The thermodynamic data for the association of (CH 3) 3Si + with ammonia were obtained using ethyl acetate as the reference base. CH 3Si + affinities increase in the order NH 3 < CH 3NH 2 < C 2H 5NH 2 < n-C 4H 9HN 2 and the absolute values increase linearly with the proton affinity of the amine. s- and t-Butyl amines have slightly lower (CH 3) 3Si + affinities than n-butyl amine which may be due to steric effects. Such effects appear to be responsible for the very low (CH 3) 3Si + transfer rate between trialkyl amines for which no thermodynamic data were obtained. It was ascertained, however, that (CH 3) 3Si + afinities increase in the order primary < secondary < tertiary amine. The proton affinities of trimethylsilyl amines derived from the (CH 3) 3Si + binding enthalpies are slightly lower (2–5 kcal mol −1) than those of their t-butyl analogues, showing, in agreement with theory, that an α-silicon is a little less effective at stabilizing positive charge on nitrogen than is an α-carbon.

Dynamic NMR, a New Technique for Determination of Proton Affinity of Amines and Anions in Aprotic Solvents

Dynamic NMR, a New Technique for Determination of Proton Affinity of Amines and Anions in Aprotic Solvents

All-valence electron calculations and proton affinity of amines

All-valence electron calculations and proton affinity of amines

Origin of alkyl substituent effect in the proton affinity of amines, alcohols, and ethers

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTOrigin of alkyl substituent effect in the proton affinity of amines, alcohols, and ethersHideaki Umeyama and Keiji MorokumaCite this: J. Am. Chem. Soc. 1976, 98, 15, 4400–4404Publication Date (Print):July 1, 1976Publication History Published online1 May 2002Published inissue 1 July 1976https://doi.org/10.1021/ja00431a011RIGHTS & PERMISSIONSArticle Views294Altmetric-Citations108LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (570 KB) Get e-Alerts Get e-Alerts