The energy spectra of tritons, a particles, and deuterons from the reactions z He (d,t)2p, d( z He,t)2p, 3 He( 3 He, 4 He)2^>, and p( z B.e,d)2p were measured at forward angles 0° to 5°, using 36-MeV deuterons and 53-MeV 3 He from the Oak Ridge isochronous cyclotron. The reaction d( z B.e,t)2p at 0° was also studied at 74 MeV. All spectra had peaks in the high-energy region which are attributed to the enhancement of the cross section due to the final-state interaction of the two protons. The final-state interaction theory of Watson and Migdat gives an adequate representation of the data for the reactions 3 He(d,02^> and 3 He( 3 He, 4 He)2^ for the known proton-proton interaction. For the other two reactions, d( z He f t)2p and p( z He,d)2p, the observed peaks are much narrower than the predictions of the Watson-Migdal theory. In the case of d( z U.e f t)2p the narrower peak could be explained by assuming the primary reaction mechanism to be a charge-exchange process. A search for a three-proton enhancement in the reaction 8 He( 3 He,Q3£ was unsuccessful.
the size of the ortho-alkyl substituents parallels changes in other constants derived from the same structural differences, as may be seen from the data in Table IV. Again, only limited comparable data are available.As to the application of the HFA technique to quantitative analysis, it can be concluded that although it is applicable to most phenols, caution should be exercised in systems where there is a bulky ortho substituent or a strong electronegative group at the meta or para position. In such systems, the equilibrium does not lie too far to the right. This, however, can be partially overcome by the presence of a great excess of free HFA. For example, to reach 99% reaction in a substituted phenol whose K with HFA is 100, a 1.0 molar excess of HFA should be present.
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