Ionization, primary secondary

Figure 3. Variation of the relative primary, secondary, and tertiary ion currents with ionization chamber concentration as predicted by the kinematic theory for the three models of complex formation, hydrogen ion, and hydrogen atom stripping. For conditions, see text...

Other treatments " have led to scales that are based on different principles, for example, the average of the ionization potential and the electron affinity, " the average one-electron energy of valence shell electrons in ground-state free atoms, or the compactness of an atom s electron cloud.In some of these treatments electronegativities can be calculated for different valence states, for different hybridizations (e.g., sp carbon atoms are more electronegative than sp, which are still more electronegative than and even differently for primary, secondary,... 

As noted previously, ionized primary and secondary alkylamines isomerize to DIs provided they have sufficiently long alkyl chains and are allowed enough time. These... 

Since phenol has an appreciable dipole moment, and no low energy acceptor orbitals, it should interact best with the donors that have the largest lone pair dipole moment — the oxygen compounds. Iodine has no dipole moment and the interaction with iodine is expected to be essentially covalent. Iodine should interact best with the donors that have the lowest ionization potential, i.e., the ones whose charge clouds are most easily polarized. Similar considerations have been employed to explain the donor strengths of primary, secondary and tertiary amines 35a) and the acid strengths of (35b) ICl, Bt2, I2. CeHsOH and SO2. 

Weak-base resins have primary, secondary or tertiary amine functional groups and, in neutral or alkaline solution, the amines are in the free-base (un-ionized) form and have no ion-exchange properties. In acidic solution, the amine groups are protonated and extract anions according to the following equations ... 

Isopentane is the smallest alkane in the series, having primary, secondary, and tertiary hydrogens. Under similar conditions as propane and isobutane, isopentane was partially ionized in DF-SbF5 at — 10°C (10% conversion) the recovered 90% of alkane showed extensive deuterium/proton exchange (12 atom% of the primary, 16 atom% of the secondary, 19 atom% of the tertiary hydrogens were exchanged as expected in accord with their relative cr-basicity).61... 

An anionic surfactant is soluble only at a pH greater than tf pqf its ionizable group, whereas a cationic surfactant (e.g., primary, secondary, ortertiary amines) is soluble only at a pH less than its pKg. However, quaternary ammonium surfactants remain soluble at all pH values. Zwitterionic surfactants, for example, sulfobetaine surfactants, are neutral from pH 2 to 12, whereas some nonionic surfactants, for example, alkyldimethylamine oxides, are converted to cationic surfactants by protonation at acidic pH. 

Generally, the evaporated mobile phase acts as the ionizing gas and reactant ions are produced from the effect of a corona discharge on the nebulized solvent. Typically, the corona discharge forms by electron ionization primary ions such as N2 + or 02 +. Then, these ions collide with vaporized solvent molecules to form secondary reactant gas ions. 

It should be mentioned that a solvent change affects not only the reaction rate, but also the reaction mechanism (see Section 5.5.7). The reaction mechanism for some haloalkanes changes from SnI to Sn2 when the solvent is changed from aqueous ethanol to acetone. On the other hand, reactions of halomethanes, which proceed in aqueous ethanol by an Sn2 mechanism, can become Sn 1 in more strongly ionizing solvents such as formic acid. For a comparison of solvent effects on nucleophilic substitution reactions at primary, secondary, and tertiary carbon atoms, see references [72, 784]. 

Chemical, electron field desorption, laser desorption, photon, plasma desorption, spark, and thermal ionization are all used as primary ionization processes. Secondary ionization is the term used to describe a process in which ions are ejected from a surface as a result of bombardment by a primary beam of atoms or ions. If low energy or soft ionization techniques are used, the mass of the target molecule can be determined. Advances in soft ionization techniques have extended the use of MS to the direct measurement of peptide and protein mass. Ionization at higher energy results in more extensive fragmentation of target molecules. 

Eksborg and Schill1 separated a series of alkylamines on a cellulose column loaded with a 0.06 M aqueous picrate solution, of pH 11.2, using as mobile phase chloroform - 1-pentanol (19 1). Addition of the alcohol to the mobile phase was necessary to reduce tailing. Celite and porous silica gel were found to be less suitable as solid support for aqueous picrate solutions. At the low pH necessary to ionize tertiary, secondary and primary amines, picrate... 

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