H2O loss

Figure 10. CID mass spectrum of precursor ion Ni(H20) o illustrating formation of sequential H2O loss down to Ni(H20)3+. From Blades, A. T. Jayaweera, P. Ikonomou, M. G. Kebarle, P. Int. J. Mass Spectrom. Ion Proc. 1990, 101, 325, with permission.

Unequivocal characterization of the transition structures involved in the anchimeric assistance to H2O loss from 26 and 28 (A = H) is obtained by the measurement of the relevant deuterium primary and secondary kinetic effects. 

Table 21 Differential Arrhenius parameters for the competing neighboring-group participation to the unimoplecular H2O loss in the chiral oxonium ions 26 and 28 (A = H)...

Example In epimeric 4-methylcyclohexanols the methyl and the hydroxyl group can either both reside in axial position (cis) or one is equatorial while the other is axial (trans). In the trans isomer, stereospecific 1,4-H20 elimination should proceed easily (Chap. 6.10.3), whereas H2O loss from the cis isomer is more demanding. CE-CI using CeFe reactant ions clearly distinguishes these stereoisomers by their M /[M-H20] ratio (trans cis = 0.09 2.0 = 23). [60]... 

Figure 19. Dependence of the unimolecular dissociation rate constant for H2O loss from the cluster ion, (H20)4H% on pressure of CH4 in the FTICR cell.

Figure 17. Average HpO loss per month ( ) and average total H2O loss (0) during 1977 for 56 systems. (Brackets indicated the maximum and minimum loss each month.)...

PROP White or colorless, triclinic, crystals or granules. Decomp on heating with H2O loss to form Na2S207 which on further heating decomp to form Na2S04. Mp ... 

Protonation of the OH group in the hemiacetal in Step [4] forms a good leaving group (H2O). Loss of H2O in Step [5] forms a resonance-stabilized cation. 

The mechanism given is in accord with the existence of inner-sphere surface complexes it illustrates that one of the water molecules coordinated to the metal ion has to dissociate in order to form an inner-sphere complex if this H2O loss is slow, then the adsorption (i.e., the binding of the metd ion to the surface ligands) is slow. 

Regardless of the microscopic phenomena, protonic conductivity is critically sensitive to the water content inside crystals and on their surface. Intrinsically nonconductive materials may apparently exhibit proton transport in wet environments due to adsorbed and/or condensed water. Consequently, numerous reports on the conductivity of compacted powders at 90-100% relative humidity, when vapor condensation in pores cannot be avoided, are excluded from consideration. Heating or cooling may cause H2O loss or uptake from the atmosphere, thus altering the conditions for proton transport in crystals. In such situations, the apparent found... 

Figure 257 is a plot of the mass (H2O) loss observed at each isothermal hold temperature. It clearly shows the trend described above. At low temperatures, there is not much structural movement to release water vapor through silanol group condensation. At 600 °C there is considerable rearrangement of the surface, allowing significant loss of water over a period of 24 h. At 800 °C the process is so fast that condensation has almost reached its equilibrium limit before the temperature has been reached. Furthermore, because most of the water has already been lost by 800 °C, the change in mass is relatively smaller. 

Dehydroxylation, for example in muscovite, involves H2O loss, and not (OH) or H2 loss alone. Therefore, it is likely that the OH group that destabilizes initially must attract the H from the adjacent OH group following the reaction 2(0H) H20(t) + Or. The... 

CH2CI (formed by H2O loss from CICH2OH9) is more stable... 

Red-violet modification. A mixture of 2.05 g. (0.008 mol) of phenylbiguanide-p-sulfonic acid and 150 ml. of water is acidified with 1.5 ml. of concentrated hydrochloric acid (35%) and warmed to 60°. To this solution is added 1 g. (0.004 mol) of copper (II) sulfate 5-hydrate dissolved in 10 ml. of water. The resulting solution is then treated with dilute (12%) ammonia water drop by drop imtil the solution becomes just alkaline and the red-violet crystals of the copper complex separate. About 4 ml. of ammonia is required. The crystals are filtered, washed first with 100 ml. of water and finally with 15 ml. of ethanol, and dried in air. Yield 2.2 g. (93% based on copper taken). Anul. Calcd. for [Cu(H03SC6H4C2NsH5)2]-H20 N, 23.59 Cu, 10.71 H2O, 3.04. Found N, 23.66 Cu, 10.61, 10.64 H2O (loss at 90°), 3.0. 

Cyclic Alcohols Many of the fragmentation reactions of cyclic alcohols are similar to those of cycloalkanes. For example, a-cleavage of the ring bond is followed by the loss of an alkene molecule to produce even-numbered OE+ ions. Hydrogen rearrangement, the snbsequent loss of alkyl radicals, and H2O loss also compete with this reaction. 

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