145384-53-8

Upstream product

• 61009-70-9 4-(3-nitrophenylazo)-salicylate ion 
• 75-50-3 trimethylamine 
• 62-53-3 Aminobenzenradikatkation 
• 75-22-9 trimethylamine-borane 
• 1033995-63-9 oxonium 
• 7732-18-5 water 

Downstream Products

• 71467-09-9 dimethyl-ethyl-ammonium cation 
• 75-50-3 trimethylamine 
• 59230-64-7 {(CH₃)2(t-C₄H₉)NH}⁽¹⁺⁾ 
• 17126-11-3 2,4-dimethylpyridine conjugate acid 
• 75-50-3 trimethylammonium radical cation 
• 61009-70-9 4-(3-nitrophenylazo)-salicylate ion 
• 2498-24-0 {(CH₃)2(cyclo-C₆H₁₁)NH}⁽¹⁺⁾ 

Relevant academic research and scientific papers

Delayed ionization following resonant photon absorption and intracluster electron transfer

Ionization of clusters comprised of paraxylene (PX) bound to NH3 and N(CH3)3 is studied following the absorption of photons through the perturbed S1 state of PX.In the case of PX*NH3 where the ionization potential of PX(8.445 eV) lies below that of NH3(10.16 eV), ionization of the cluster near the ionization threshold of PX leads to the formation of the cluster ion (PX*NH3)+.By contrast, for clusters of PX*N(CH3)3 where the ionization potential of N(CH3)3 (7.82 eV) lies below that of PX, resonance absorption through high Rydberg states of PX below its I.P. leads to the production of N(CH3)3+ and H+*N(CH3)3, but no parent cluster ions.In this case, following photon absorption the ionization and formation of N(CH3)3+ is substantially delayed for times ranging from 160-200 ns, the longer values being obtained at lower photon energies.

Gas-phase basicity measurements of dipeptides that contain valine

Gas-phase basicities of 22 dipeptides that contain valine were measured by a double bracketing method in a Fourier transform ion cyclotron resonance spectrometer. Matrix-assisted laser desorption was used to generate protonated peptide ions which were reacted with reference compounds to bracket the gas-phase basicity. In addition, neutral peptide molecules were formed by substrate-assisted laser desorption and with protonated reference ions to confirm the assignment of the gas-phase basicity. The rate of proton transfer between the protonated molecule of alanylvaline and six reference compounds was measured to examine the behavior of both exoergic and endoergic reactions. Gas-phase basicities of most of the dipeptides were found to be nearly equal to that of their most basic amino acid residue. The results are consistent with an intramolecular hydrogen bond between the N-terminus nitrogen and the amide carbonyl oxygen of a dipeptide. Furthermore, the results suggest that inductive effects cause an increase in the strength of the intramolecular hydrogen bond that the in the basicity of the C-terminus amino acid residue. Dipeptides VF and VY are more basic than their constituent amino acids. These data and molecular mechanics calculations suggest that these two peptides are stabilized by an electrostatic interaction between the N-terminal ammonium ion and the polarizable electrons of the aromatic side chain of the C-terminus.

The Oxidation of Trimethylamine by OH Radicals in Aqueous Solution, as Studied by Pulse Radiolysis, ESR, and Product Analysis. The Reactions of the Alkylamine Radical Cation, the Aminoalkyl Radical, and the Protonated Aminoalkyl Radical

Hydroxyl radical reactions with trimethylamine in aqueous solution lead to the formation of the aminoalkyl radical (A(.)) and its conjugated acid (AH(+.)) as well as to the alkylamine radical cation (CH3)3N(+.) (N(+.)).These radicals are transformed into each other by hydrolytic reactions, e.g. Radicals AH(+.) are more acidic (pKa ca. 3.6) than the radicals N(+.) (pKa ca. 8.0).Consequently, N(+.) predominate over AH(+.) under quasi equilibrium conditions (e.g. in the presence of phosphate buffer) and are the only species observed by ESR in acid solutions.Reacting with the protonated amine, OH radicals abstract hydrogen at nitrogen and at carbon with comparable ease.Reaction of OH radicals with the free amine may initially also generate N(+.), beside H-abstraction at carbon.Radicals A(.) absorb more strongly at 260 nm (ε = 3390 dm3mol-1cm-1) than the radical cation N(+.) (ε = 950 dm3mol-1cm-1).Radical A(.) has reducing properties whereas radicals AH(+.) and N(+.) have oxidizing properties and hence can be monitored with p-nitroacetophenone (the reducing radicals), and Fe(CN)6(4-), N,N'-tetramethyl-p-phenylenediamine and 2,2'-azinobis-(3-ethyl-benzthiazoline-6-sulphonate) (the oxidizing radicals).These radicals mainly (>/=85percent) disproportionate, one of the products being formaldehyde. - Keywords: Radiation Chemistry, Amines, Electron Transfer, Hydrogen Abstraction, Reaction Kinetics

Unconventional Ionic Hydrogen Bonds. 2. NH(1+)...? Complexes of Onium Ions with Olefins and Benzene Derivatives

Unconventional strong ionic hydrogen bonds of the -XH(1+)...? type, where the electron donor is a ?-bond or an aromatic ?-system, are formed in the clustering reactions of NH4(1+) and MeNH3(1+) with C2H4 and benzene derivatives.The interaction energies range from 10 to 22 kcal mol-1.The experimental results and ab initio calculations on C2H4*NH4(1+), C6H6*NH4(1+), and C6H5F*NH4(1+) indicate that the interaction is primarily electrostatic in nature with little ?-donation into the bond.The most stable structure of C2H4*NH4(1+) is the conformer where one N-H(1+) bond points at the center of the double bond.For C6H6*NH4(1+) and C6H5F*NH4(1+), the lowest energy ?-dimers have two NH4(1+) hydrogens directed towards the ring.The F...H-NH3(1+) ?-complex was studied also for C6H5F*NH4(1+).The latter complex is the more stable of the two at this level of calculation.

IONIC HYDROGEN BOND. 4. INTRAMOLECULAR AND MULTIPLE BONDS. PROTONATION AND COMPLEXES OF AMIDES AND AMINO ACID DERIVATIVES.

The paper examines the proton affinities and ionic hydrogen bonding of some amides and of the N-acetylated amino acid derivative CH//3CONHCH(CH//3)COOCH//3. The thermochemistry of these species can serve as a model for the energetics of protonated intermediates in acid hydrolysis of amides and the energetics of protonated amide groups in proteins.

The Ionic Hydrogen Bond. 2. Multiple NH+...O and CH?+...O Bonds. Complexes of Ammonium Ions with Polyethers and Crown Ethers

Complexes of ammonium ions RNH3+ (R = CH3, c-C6H11), (CH3)3NH+, and pyridineH+ with polyethers and crown ethers are observed in the gas phase in the abscence of the solvent effects.The dissociation energies, ΔH0D, of the RNH3+ polyether complexes range from 29.4 kcal mol-1 (for RNH3+*CH3OCH2CH2OCH3) to 46 kcal mol-1 (RNH3+*18-crown-6).The large ΔH0D values for complexes of polydentate ligands indicate multiple -NH+...O-hydrogen bonding.Such mutiple bonding can contribute up to 18 kcal mol-1 to the bonding in RNH3+*CH3(OCH2CH2)3OCH3 and 21 kcal mol-1 in RNH3+*18-crown-6.Multiple interactions are also evident in the (CH3)3NH+*polyether complexes where -CH?+...O-hydrogen bonding seems to occur; and consecutive -CH?+...O-bonds contribute approximately 6, 4, and 2 kcal/mol-1 respectively for up to three such bonds.Total ΔH0D values in the (CH3)3NH+*polyether complexes thus range from 26.7 kcal mol-1 in (CH3)3NH+*CH3O(CH2)2OCH3 to 41 kcal mol-1 in (CH3)3NH+*18-crown-6.Multiple interaction effects, possibly including van der Waals dispersion forces, are observed also in pyridineH+*polyether complexes.Large negative entropies in RNH3+*acyclic polyether complexes vs.RNH3+*cyclic crown ethers make the acyclic polyethers less efficient ligands.

Carbon-Hydrogen Bond Dissociation Energies in Alkylbenzenes. Proton Affinities of the Radicals and the Absolute Proton Affinity Scale

Rate constants (k) were measured for proton-transfer reactions from alkylbenzene ions RH+ to a series of reference bases B, i.e., RH+ + B -> BH+ + R*.For exothermic reactions (ΔH -1.For example, the reaction C6H5CH3+ + B -> BH+ + C6H5CH2* is fast (reaction efficiency = k/kcol >/= 0.5) when B = MeO-t-Bu or stronger bases, but k/kcol is significantly smaller when B is n-Pr2O or weaker bases.From the falloff curve of reaction efficiency vs.PA(B), we find PA(n-Pr2O) = PA(C6H5CH2*) + 0.8 kcal mol-1 = 200.0 kcal mol-1.Since PA(C6H5CH2*) is obtained from known thermochemical data, this relation defines the absolute PA of n-Pr2O.Through a ladder of known PA, we then obtain PA(i-C4H8) = 186.8 kcal mol-1; we also obtain the absolute PAs of other oxygen bases.Falloff curves of reaction efficiencies of 3-FC6H4CH3+, C6H5C2H5+, C6H5-n-C3H7+, and C6H5-i-C3H7+ with these reference bases give then the following PAs of R* and R-H bond dissociation energies (Do) (all in kcal mol-1) as R*, PA(R*), Do(R-H): 3-FC6H4CH2*, 197.2, 89.4; , 197.9, 86.2; , 199.1, 86.1; , 199.6, 86.1.In similar manner, rate constants for H+ transfer from C6H5NH2+ to reference pyridines and amines yield PA(C6H5NH*) = 221.5 and Do(C6H5NH-H) = 85.1 kcal mol-1 (1 kcal mol-1 = 4.18 kJ mol-1).

Kinetic and Equilibrium Solvent Isotope Effects on the Deprotonation of a Salicylate Ion by Hydroxide Ion and General Bases

Kinetic and equilibrium solvent isotope effects has been measured for proton transfer from 4-(3-nitrophenylazo)-salicylate ion (HA) to general bases (B) to examine whether a primary kinetic isotope effect is observed when proton transfer is occurring between bases of roughly equal strength for which ΔpK = pKHA - pKBH(1+) = 0.The kinetic solvent isotope effects for catalysis by three tertiary amines (ΔpK -0.85, -0.27, and +0.28) are kBH2O/kBD2O 2.0 +/-0.3, and 1.7 +/-0.2.Since for proton transfer to hydroxide ion (ΔpK -5.0) the isotope effect has a value kOH(1-)H2O(1-)/kOD(1-)D2O of 1.5 +/-0.1, the primary isotope effect for these proton transfers must be small and independent of base strength over the range studied.An explanation in terms of the reaction mechanisms is given.