Page 1199 - Advanced Organic Chemistry Part A - Structure and Mechanisms, 5th ed (2007) - Carey _ Sundberg

1186 2,4-hexadiene hydroboration, 521–526
photocyclization of, 1102 electrophilic character of, 522
Index hexahelicene enantioselective, 529–531
chirality of, 130 mechanism of, 522
hexamethylphosphoric triamide reagents for, 521, 524–525
effect on enolate alkylation, 616 regioselectivity of, table, 523
effect on enolate composition, 596 stereoselectivity, 187–188
1,3,5-hexatriene derivatives steric effects in, 523
electrocyclization reactions of, 895, 899–900 hydrocarbons, see also alkanes, alkenes, etc.
photochemical, 1106–1107 acidity of, 368–376, 579–587
excited states computation of, 56–57, 586
computational modeling of, 1142–1144 effect of anion delocalization, 375
Hückel MO orbitals for, 29 electrochemical determination of, 372, 584
5-hexenyl radical gas phase, 585–586
cyclization of, 1009-1011 hybridization effect on, 373, 376, 584–585
high performance liquid chromatography measurement of, 580–584
in separation of enantiomers, 211–213 in relation to anion aromaticity, 740
HMPA, see hexamethylphosphoric triamide table of, 371, 583
Hofmann-Loeffler reaction, 1040 aromatic
Hofmann rule, 556 fused ring systems, 745–758
HOMA, see harmonic oscillator model for hardness of, 750, 795
aromaticity photochemical reactions of, 1134–1137
HOMO, 15, 29, 44, 97 redox potentials for, 990
distribution, in relation to electrophilic aromatic stability comparisons for, 715–718, 746–748
substitution, 783 autoxidation of, 995
homoaromaticity, 743–745 bond dissociation energies for, 1053
in cyclooctatrienyl cation, 743 bond orders for, 77
homodesmotic reactions, 265–267 bromination of
in estimation of aromatic stabilization, 716–717 Bell-Evans-Polyani relationship for, 288
HOMO-LUMO gap, 750 by free radical substitution, 1018–1020, 1022
relationship to hardness, 15 computation of enthalpy of formation by MO
homolytic bond cleavage, definition, 965 methods, 52
examples, 965 enthalpy of formation, table, 256
homotropilidene, see bicyclo[5.2.0]octa-3,5-diene calculation by MO and DFT methods,
homotropylium ion, see cyclooctatrienyl cation 265–269
HPLC, see high performance liquid calculation using group equivalents, 29
chromatography relation to structure, 256
HSAB theory, see hard-soft acid-base theory fluorination of, 1023
Hückel’s rule, 713, 738 halogenation of
application to charged rings, 742–743 by radical substitution, 1018–1024
Hückel MO Method, 27–32 by tetrahalomethanes, 1003
hybridization, 4–7 octane numbers of, 454
in allene, 6 polycyclic aromatic
in cyclopropane, 85–86 aromaticity of, 749–751
effect on electronegativity of carbon, 12–13 electrophilic substitution of, 791–793
effect on hydrocarbon acidity, 373, 376, strained, bonding in, 87–89
584–585 hydrocracking, 454–456
sp,5 hydrogenation, catalytic
2
sp ,5 catalysts for, 173–174
3
sp ,5 enantioselective, 189–193
hydration of , -unsaturated carboxylic acids, 190
of alkenes, 474, 482–484 of -amidoacrylic acids, 191–192
of carbonyl compounds, 329, 638–639 heterogeneous catalysis, 172
hydrazone, 646 homogeneous catalysis, 172
mechanism of formation, 651 mechanism of, 172, 174, 189–192
hydride affinity stereoselectivity of, 170–176
of carbocation, 303 substituent directive effects in, 171–176
of carbonyl compound hydrogen atom abstraction reactions, 1001–1004
table, 330 by bromine atoms, 288