MINISTRY OF SCIENCE AND TECHNOLOGY
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Title: Search for Maximal Neighboring Group Participation in
Solvolyses of Allylic Substrates. Ethanolysis of
2-(/omega/-Alkylthioalkyl)-3-methyl-2-cyclohexyl p-Nitrobenzoates
Title: Confirmation of the H-Bridged Structure of the 2-Butyl
Cation by Comparison of Experimental and Ab initio IR Frequencies
Title: Isolation and the IR Spectra of Chloro- and Bromo-ethyl
Cations in Cryogenic SbF5 Matrices
Title: Characteristic Frequencies of Hydrogen-Bridged
Carbocations. IR-Spectra and Ab Initio Calculations of the Nonclassical
Structures of the Cyclooctyl Cation.
Title: Vibrational Spectra of C5H7+ Isomers in Low-temperature
Antimony Pentafluoride Matrices.
Title: The Nature of the 7-Norbornyl Cation and its Rearrangement
into the 2-Norbornyl Cation
Title: Hydrolysis of Some Unsaturated N-methyl-nicotinates in
Micelle and in Cyclodextrin
Faculty: Prirodoslovno-matematički Zagreb
Date of defense: 07/02/93
Language: hrvatski
Number of pages: 119
Summary: Iodine-2-(/delta/3-cyclopentenyl-ethyl)-N-methyl-nicotinate
(17),iodine-3-(/delta/3-cyclopentenyl-propyl)-N-methyl-nicotinate(18),
iodine-neryl-N-methyl-nicotinate (19),iodine-geranyl-N-methyl-nicotinate
(20),iodine-linalyl-N-methyl-nicotinate (21)
andiodine-/alpha/-terpinyl-N-methyl-nicotinate (22) were synthesizedand
hydrolyzed in water, aqueous solutions of /alpha/- and/beta/-cyclodextrins
(CD) and different aqueous solutions ot=fthe cetyltrimethylammonium bromide
(CTAB). The choice of theleaving group and medium influences the reaction
rate andcomposition of products. Contrary to published data, thehydrolysis
of 17 in the presence of /alpha/-CD yieldsendo-2-norborneol while terpenes
19-21 afford different ammountsof 4-terpineol.
Keywords: terpenes, nicotinate, synthesis, hydrolysis, water, micelle, cyclodextrin, cyclization
Title: Infrared Spectroscopy of C4H7+ Ions in Cryogenic Matrices
Faculty: Prirodoslovno-matematički Zagreb
Date of defense: 05/10/93
Language: hrvatski
Number of pages: 114
Summary: The structures of C4H7+ ions have been studied on the basis
oftheir IR specta recorded in cryogenic antimony pentafluoridematrices.
Nonclassical bicyclobutonium ion has been investigatedin detail. In
addition, the influence of the methyl groupsubstitution in the
bicyclobutonium ion has been studied. Thegenerated spectra have been
compared with the ones calculated ona high ab initio level.
Keywords: cyclopropylcarbinyl kation, cyclobutyl cation, 1-methylalyl cation, 1-methylcyclobutyl cation, nonclassical carbocation, bicyclobutonium ion, matrix isolation technique, antimony(V)-fluoride
Title: Quantum-Mechanical Study of Ketone-Lewis Acid Complexes
Faculty: Prirodoslovno-matematički Zagreb
Author: MIHALIĆ ZLATKO
Date of defense: 10/19/94
Language: hrvatski
Number of pages: 81
Summary: Systematic examination of ketone-Lewis acid complexes were
performed by means of molecular-orbital semiempirical (AM1 and PM3) and ab
initio (HF/3-21G, HF/6-31G*, HF/6-31G** and MP2(FC)/6-31G*)
quantum-mechanical calculations. In all cases n1 (s) ketone-Lewis acid
coordination was observed. As a result of complex formation, C=O bond
lengthens, and its bond-order decreases. Positive charge that develops on
carbonyl carbon atom causes electron-density reorganization in the rest of
the molecule. In all cases significant hyperconjugative electron donation
by suitably positioned C-H and C-b neighboring bonds occurred, accompanied
by their lengthening and significant (O=)C-C bond shortening.
Calculated
ketone C=O bond IR stretching frequencies and corresponding protonated
ketones frequencies were compared with experimental IR spectra recorded in
solid antimony(V)-fluoride cryogenic matrix. Semiempirical and ab-initio
calculations with small basis set (HF/3-21G) successfully reproduced
experimental ketone frequencies, but failed to explain the origin of
vibrational frequencies differences caused by SbF5 complexation. Larger
basis set with polarization functions on heavy atoms (HF/6-31G*) gave good
agreement with experimental frequency changes in case of ketones similar to
"classical" carbocations, where dominant effect is inductive charge
stabilization. This level of theory was also not sufficient to explain
"nonclassical" effect responsible for deviations from linear correlation
found in the case of simple ketones. It was only the Moller-Plesset
second-order correlation correction (MP(FC)/6-31G*) that successfully
reproduced the experimental trends. Calculated C=O bond lengthening that
results from ketone protonation at MP(FC)/6-31G* level completely agrees
with experimental C=O bond stretching frequency difference that results
from SbF5 complex formation.
Keywords: ketones, Lewis acids, semiempirical quantum-mechanical calculations, ab-initio quantum-mechanical calculations, antimony(v)-fluoride, bor(III)-fluoride, protonated ketones, vibrational spectra, cyclobutanone, cyclopropyl-methyl-ketone
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