Negative ions proton transfer

Veres, P., Roberts, J. M., Wameke, C. et al. (2008) Development of negative-ion-proton-transfer chemical-ionisation mass spectrometry (NI-PT-CIMS) for the measurement of gas-phase organic acids in the atmosphere. Int. J. Mass Spectrom. 274,48. 

Several processes are unique to ions. A common reaction type in which no chemical rearrangement occurs but rather an electron is transferred to a positive ion or from a negative ion is tenued charge transfer or electron transfer. Proton transfer is also conunon in both positive and negative ion reactions. Many proton- and electron-transfer reactions occur at or near the collision rate [72]. A reaction pertaining only to negative ions is associative detaclunent [73, 74],... 

The proton transfer equilibrium that interconverts a carbonyl compound and its enol can be catalyzed by bases as well as by acids Figure 18 3 illustrates the roles of hydroxide ion and water m a base catalyzed enolization As m acid catalyzed enolization protons are transferred sequentially rather than m a single step First (step 1) the base abstracts a proton from the a carbon atom to yield an anion This anion is a resonance stabilized species Its negative charge is shared by the a carbon atom and the carbonyl oxygen... 

In any pure liquid, the transfer of a proton from one molecule to another (distant) molecule has been named autoprololysis. I11 any solvent this process creates a positive and a negative ion and must clearly belong to class II it will not differ from other proton transfers of class II except for the fact that the relation between Kx and K will be different. On the left-hand side of (127) and (128) there is no solute particle hence the increase in the cratic term is greater than in (119) or (121). In (128) we have Aq — +2, and... 

The Dissociation Constant of Nitric Add. Alodcrately Weak Acids. The Variation of J with Temperature. Proton Transfers between Solute Particles. A Proton Transfer in Methanol Solution. Proton Transfers with a Negative Value for. / . The Hydrolysis of Salts. Molecules with Symmetry. Substituted Ammonium Ions. Deuteron Transfers in D2(). The Dissociation of Molecular Ions. 

There are, in fact, two reasons why we should prefer to discuss proton transfers of class I. In concentrated solutions the average electrostatic forces between the ions will be intense. Only in proton transfers of class I does the number of positive and negative charges in the solution remain unaltered when the proton is transferred only here do we find the possibility that the contribution from the interionic forces will remain almost unchanged in a proton transfer. At the same time, although the number... 

It was pointed out in Sec. 126 that in any proton transfer of class I the number of negative ions remains unchanged and the number of positive ions remains unchanged and consequently there is the possibility that the contribution from the interionic forces shall remain unchanged. Whether this is so or not can be decided only by experiment. Consider what result should be obtained if (218) and (219) are applicable. In this case, if experimental values of the left-hand side of (218) are plotted... 

Chemical ionization (Cl) The formation of new ionized species when gaseous molecules interact with ions. This process may involve the transfer of an electron, proton, or other charged species between the reactants in an ion-molecule reaction. Cl refers to positive ions, and negative Cl is used for negative ions. 

Up to this point, we have dealt with the subject of acid-base chemistry in terms of proton transfer. If we seek to learn what it is that makes NH3 a base that can accept a proton, we find that it is because there is an unshared pair of electrons on the nitrogen atom where the proton can attach. Conversely, it is the fact that the hydrogen ion seeks a center of negative charge that makes it leave an acid such as HC1 and attach to the ammonia molecule. In other words, it is the presence of an unshared pair of electrons on the base that results in proton transfer. Sometimes known as the electronic theory of acids and bases, this shows that the essential characteristics of acids and bases do not always depend on the transfer of a proton. This approach to acid-base chemistry was first developed by G. N. Lewis in the 1920s. 

Because of its high negative charge density, the oxide ion is a very strong Bronsted base. Therefore, when an ionic oxide is placed in water, there is proton transfer to produce hydroxide ions. 

Termination can occur by proton transfer to negatively charged counter ion. 

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