Surface photochemistry: 13C enrichment by photolysis on silica gel

1984 ◽  
Vol 62 (10) ◽  
pp. 1999-2005 ◽  
Author(s):  
Linda J. Johnston ◽  
S. King Wong
Keyword(s):  
Silica Gel ◽  
Silica Surface ◽  
Isotope Separation ◽  
Single Stage ◽  
Starting Material ◽  
Radical Pairs ◽  
Radical Recombination ◽  
Separation Factors

The enrichment of the 13C isotope by partial photolysis of dibenzyl ketone on silica gel has been demonstrated. The 13C enrichment is substantial and is parallel to the increase in the probability of geminate radical recombination on a silica surface as compared with that in solution. A substantial 13C enrichment was also observed for the rearranged starting material, 1-phenyl-4′-methylacetophenone. The single-stage isotope separation factors are different for the two ketones although both are isomers derived from the same benzyl–phenylacetyl radical pairs.

Surface photochemistry: generation of benzyl radical pairs on dry silica gel

1984 ◽  
Vol 62 (3) ◽  
pp. 403-410 ◽  
Author(s):  
Bradley Frederick ◽  
Linda J. Johnston ◽  
Paul De Mayo ◽  
S. King Wong
Keyword(s):  
Silica Gel ◽  
Radical Pair ◽  
Translational Motion ◽  
The State ◽  
Radical Pairs ◽  
Radical Recombination ◽  
Benzyl Radical ◽  
Radical Movement

Singlet and triplet benzyl radical pairs have been generated on silica gel by photolysis of a benzyl phenylacetate, a dibenzyl ketone, and a dibenzyl sulfone. The extent of geminate radical recombination has been measured and requires that translational motion of radicals occur on the silica gel surface. This motion was affected by the radical pair multiplicity and the photolysis temperature, but was relatively insensitive to the state of hydration of the silica gel and the presence of coadsorbates. The presence of certain rearranged starting materials, which are not formed in solution, amongst the products from photolysis of both dibenzyl ketone and dibenzyl sulfone on silica gel indicates the restrictions on radical movement on the surface on the shorter timescale of the benzyl–phenylacetyl and benzyl – benzyl sulfonyl radical pairs.

Ion Beam Measurement of Deuterium in Palladium and Calculation of Hydrogen Isotope Separation Factors

1991 ◽  
Vol 138 (8) ◽  
pp. L26-L27 ◽  
Author(s):  
T. R. Guilinger ◽  
M. J. Kelly ◽  
J. A. Knapp ◽  
D. S. Walsh ◽  
B. L. Doyle
Keyword(s):  
Hydrogen Isotope ◽  
Ion Beam ◽  
Isotope Separation ◽  
Separation Factors

Direct Reaction of Silica Gel with Butyllithium

2007 ◽  
Vol 2007 (9) ◽  
pp. 538-540
Author(s):  
Robert D. Guthrie
Keyword(s):  
Silica Gel ◽  
Silica Surface ◽  
Cold Water ◽  
Polar Compounds ◽  
Chromatographic Retention ◽  
Direct Reaction ◽  
Modified Silica Gel ◽  
Surface Areas ◽  
Butyl Group ◽  
Unmodified Silica

Silica gel with a variety of surface areas is found to react directly (no SOCl2 treatment required) with butyllithium to give a product with butyl groups attached. The extent of butyl group incorporation depends on available silica surface. With dehydrated 230–400 mesh silica gel, 7.4 mmoles of BuLi per g in pentane added in hexane gave silica with 2.5 mmoles of butyl groups per g provided that the silica gel was washed three times with cold water. It was found that water washing removes some unbutylated silicate increasing the apparent butyl group incorporation. The butyl-modified silica gel showed no chromatographic retention of 3-aminoquinoline in 50:50 hexane: dichloromethane or of thymol in hexane in contrast to unmodified silica gel which is known to strongly retain polar compounds, particularly basic ones. This contrast is demonstrated.

scholarly journals Adsorption of Alcohols from Multicomponent Solutions onto Silica Gel

1986 ◽  
Vol 3 (3) ◽  
pp. 141-147 ◽  
Author(s):  
J. Goworek
Keyword(s):  
Silica Gel ◽  
Silica Surface ◽  
Material Balance ◽  
Surface Phase ◽  
Excess Adsorption ◽  
Adsorption Equilibria ◽  
Ternary Solutions ◽  
Multicomponent Solutions ◽  
Binary And Ternary Solutions ◽  
Alcohol Benzene

Adsorption equilibria of the binary and ternary solutions of alcohols in benzene and n-heptane on silica gel have been studied in order to clarify their mechanisms of adsorption. Excess adsorption isotherms have been measured for hydrocarbon solutions of methanol, ethanol, butanol and pentanol. Interpretation of the experimental data was performed in terms of material balance between bulk and surface phase. In n-heptane solutions the multilayer surface structure is formed and the surface phase contains the alcohol only. For benzene and ternary (alcohol + benzene + n-heptane) solutions a mixed surface phase is observed whose composition is determined by competition of liquid components for silica surface as well as its tendency to complex. Moreover, the extent of adsorption in methanol systems is connected with the miscibility of liquid components.

Lithium isotope separation factors of some two‐phase equilibrium systems

1976 ◽  
Vol 64 (4) ◽  
pp. 1828-1837 ◽  
Author(s):  
A. A. Palko ◽  
J. S. Drury ◽  
G. M. Begun
Keyword(s):  
Phase Equilibrium ◽  
Isotope Separation ◽  
Lithium Isotope ◽  
Two Phase ◽  
Separation Factors

Preparation of Imprinted Polymer with D-Phenylalanin on Silica Surface

2009 ◽  
Vol 419-420 ◽  
pp. 541-544
Author(s):  
Hong Xing Dong ◽  
Qiu Li Jiang ◽  
Fei Tong ◽  
Zhen Xing Wang ◽  
Jin Yong Tang
Keyword(s):  
Silica Gel ◽  
High Performance ◽  
Silica Surface ◽  
Solid Phase ◽  
Adsorption Property ◽  
Research Field ◽  
Imprinted Polymer ◽  
Modified Silica ◽  
Modified Silica Gel ◽  
Functional Monomers

Silica gel was modified with polymerizable double bonds on the surface. Then the molecular imprinting polymer imprinted with D-Phenylalanin was grafted on the surface of modified silica gel. The molecularly imprinted polymer (MIP) based on the surface of silica gel was characterized by IR and scanning electron microscopy (SEM). The adsorption property of D-Phenylalanin by MIP was mearsured. The MIP with the combined functional monomers exhibited better adsorption properties and selectivity compared with the corresponding non-imprinted polymers or MIP with the single functional monomer. The material could be used in separation research field, such as packing material of high performance liquid chromatography, solid-phase extraction and so on.

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