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Heavy-atom kinetic isotope effects in solving mechanisms of benzidine rearrangements: hydrazobenzene and 2,2'-dimethoxyhydrazobenzene

Thesis/Dissertation ·
OSTI ID:5738730
In order to elucidate the mechanism of the acid-catalyzed benzidine rearrangements, hydrazobenzene (1) and 2,2'-dimethoxyhydrazobenzene, (2) were employed as model compounds in a mechanistic study. In the case of 1, a secondary deuterium kinetic isotope effect (KIE) was determined. The first experimental approach was to measure rates of rearrangement in a traditional way, namely with 1 and (4,4'-/sup 2/H/sub 2/)-1 separately, and using the Bindschedler's Green-titrimetric method. An inverse secondary deuterium KIE of 6% was obtained but was not sufficiently convincing, considering the low accuracy of the kinetic method. In view of this, a less traditional but more reliable technique: isotope-ratio mass spectrometry was used. In the case of 2, a nitrogen and a carbon KIE were determined. Using mixtures of 2 and (/sup 15/N, /sup 15/N')-2, a primary nitrogen KIE (k(/sup 14/N)/k(/sup 15/N) = 1.029) was obtained for the formation of 3,3'-dimethoxybenzidine from the rearrangement of 2 and (4,4'-/sup 13/C/sub 2/)-2. The primary nitrogen and carbon KIE indicate the concerted formation of the 3,3'-dimethoxybenzidine. The concerted formation of the 3,3'-dimethoxybenzidine was supported by the measurement of an inverse secondary deuterium KIE (k(/sup 1/H)/k(/sup 2/H) = 0.93).
OSTI ID:
5738730
Country of Publication:
United States
Language:
English

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Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400301* -- Organic Chemistry-- Chemical & Physicochemical Properties-- (-1987)
AMINES
AROMATICS
BENZIDINE
CARBON 13
CARBON ISOTOPES
CHEMICAL REACTION KINETICS
DATA
DEUTERIUM
EVEN-ODD NUCLEI
EXPERIMENTAL DATA
HYDROGEN ISOTOPES
INFORMATION
ISOTOPE EFFECTS
ISOTOPES
ISOTOPIC EXCHANGE
KINETICS
LIGHT NUCLEI
MASS SPECTROSCOPY
NITROGEN 15
NITROGEN ISOTOPES
NUCLEI
NUMERICAL DATA
ODD-EVEN NUCLEI
ODD-ODD NUCLEI
ORGANIC COMPOUNDS
REACTION KINETICS
SPECTROSCOPY
STABLE ISOTOPES
STRUCTURAL CHEMICAL ANALYSIS