ESR-ENDOR study of x-irradiated single crystals of. cap alpha. -D-glucopyranose and. cap alpha. -methyl-D-glucopyranoside; environmental effects upon radiation and free radical chemistry in carbohydrate model systems
Single crystals of x-irradiated ..cap alpha..-D-glucopyranose (..cap alpha..Glu) and ..cap alpha..-methyl-D-glucopyranoside (..cap alpha..MeGlu) were studied to determine products and reaction mechanisms in carbohydrate radiation and free-radical chemistry. Four free-radical products were identified in ..cap alpha..MeGlu single crystals at 77K; a reoriented 06 primary alkoxy radical (06RPA), an 02 secondary alkoxy radical (02SA), a deprotonated C6 primary hydroxyalkyl radical (C6DPH), and a C5 secondary oxyalkyl radical (C5S0). Irradiation and observation at 12K produced an unreoriented 06 primary alkoxy radical (06PA). Four free radicals were identified in ..cap alpha..Glu single crystals at 12K and 77K; two different 02 secondary alkoxy radicals (02SA and 02SA'), a C6 primary hydroxyalkyl radical (C6PH), and a C3 secondary hydroxyalkyl radical (C3SH). Study of the free radical environment about 06 in ..cap alpha..Glu and ..cap alpha..MeGlu indicated that the 06-H(06) bond in ..cap alpha..MeGlu has considerably more ionic character than its counterpart in ..cap alpha..Glu. The presence of an additional hydrogen bond to 06 in ..cap alpha..MeGlu was used to explain the reorientation of the 06PA radical, and the stability of this species in the ..cap alpha..MeGlu host crystal. Free radical reactions in ..cap alpha..Glu and ..cap alpha..MeGlu were induced by slowly warming crystals irradiated at 77K until conversion occurred. In ..cap alpha..MeGlu, the major reaction sequence was C6DPH ..-->.. C550 ..-->.. C2 primary hydroxyalkyl radical (C2PH) ..-->.. room temperature allylic radical. In ..cap alpha..MeGlu, the major pathway is C6PH ..-->.. C2PH ..-->.. C2 secondary hydroxylkyl radical (C2SH). Environmental influences upon these free-radical reaction mechanisms are discussed. The results from previous work on irradiated aqueous glasses of ..cap alpha..Glu are briefly reviewed, and compared to those obtained from the single crystal system. (ERB)
- Research Organization:
- Rochester Univ., NY (USA). Dept. of Radiation Biology and Biophysics
- DOE Contract Number:
- EY-76-C-02-3490
- OSTI ID:
- 5824911
- Report Number(s):
- UR-3490/LCP-18
- Country of Publication:
- United States
- Language:
- English
Similar Records
1,2 hydrogen shift and other thermally induced free radical reactions in x-irradiated methyl. cap alpha. -D-glucopyranoside single crystals. An ESR-ENDOR study
ESR study of the attack of photolytically produced hydroxyl radicals on. cap alpha. -methyl-D-glucopyranoside in aqueous solution
Related Subjects
400600 -- Radiation Chemistry
550200 -- Biochemistry
560111* -- Radiation Effects on Biochemicals-- In Vitro-- (-1987)
59 BASIC BIOLOGICAL SCIENCES
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
CHEMICAL RADIATION EFFECTS
CHEMICAL REACTIONS
CHEMISTRY
COMPARATIVE EVALUATIONS
CRYSTALS
DATA
DATA FORMS
ELECTROMAGNETIC RADIATION
ELECTRON SPIN RESONANCE
ENDOR
EXPERIMENTAL DATA
HETEROCYCLIC COMPOUNDS
IN VITRO
INFORMATION
IONIZING RADIATIONS
IRRADIATION
ISOLATED VALUES
KINETICS
LOW TEMPERATURE
MAGNETIC RESONANCE
MONOCRYSTALS
NUMERICAL DATA
ORGANIC COMPOUNDS
ORGANIC OXYGEN COMPOUNDS
PYRANS
RADIATION CHEMISTRY
RADIATION EFFECTS
RADIATIONS
RADICALS
RADIOINDUCTION
REACTION KINETICS
RESONANCE
ULTRALOW TEMPERATURE
X RADIATION