Showing papers on "Benzophenone published in 2002"
TL;DR: In this article, the rate constants for several reduction and oxidation reactions were determined by pulse radiolysis in three ionic liquids and compared with rate constants in other solvents.
Abstract: Rate constants for several reduction and oxidation reactions were determined by pulse radiolysis in three ionic liquids and compared with rate constants in other solvents. Radiolysis of the ionic liquids methyltributylammonium bis(trifluoromethylsulfonyl)imide (R4NNTf2), N-butylpyridinium tetrafluoroborate (BuPyBF4), and N-butyl-4-methylpyridinium hexafluorophosphate (BuPicPF6) leads to formation of solvated electrons and organic radicals. In R4NNTf2 the solvated electrons do not react rapidly with the solvent and were reacted with several solutes, including CCl4, benzophenone, and quinones. In the pyridinium ionic liquids the solvated electrons react with the pyridinium moiety to produce a pyridinyl radical, which, in turn, can transfer an electron to various acceptors. The rate constant for reduction of duroquinone by the benzophenone ketyl radical in R4NNTf2 (k = 2 × 107 L mol-1 s-1) is much lower than that measured in water (k = 2 × 109 L mol-1 s-1) due to the high viscosity of the ionic liquid. Rate ...
129 citations
TL;DR: The polyoxomolydate of the Keggin structure catalyzes oxygen transfer from sulfoxides to alkylarenes such as xanthene and diphenylmethane to yield xanthen-9-one and benzophenone to yield 9-phenylfluorene as the major product.
Abstract: The polyoxomolydate of the Keggin structure, PMo12O403-, catalyzes, under anaerobic conditions, oxygen transfer from sulfoxides to alkylarenes such as xanthene and diphenylmethane to yield xanthen-9-one and benzophenone, respectively. With use of 17O and 18O labeled phenylmethylsulfoxide it was shown that the sulfoxide is complexed by the polyoxometalate and the oxygen is transferred from the sulfoxide to the alkylarene. There is a good correlation between the reaction rate and the heterolytic benzylic C−H bond energy indicating a hydride transfer reaction from the alkylarene to the polyoxometalate−sulfoxide complex. In the case of triphenylmethane the resulting carbocation reacts to yield 9-phenylfluorene as the major product. The reaction kinetics supports such a reaction pathway.
121 citations
TL;DR: In this article, copper metal nanoparticles have been formed by irradiation with 253.7 nm light from a low pressure Hg-arc lamp in the presence of a protective agent gelatin.
87 citations
TL;DR: In this paper, the mechanism and kinetics of the reaction have been studied by means of nanosecond laser flash photolysis, time-resolved emission spectroscopy and also steady-state photolyisation.
Abstract: Sensitized photoreduction of Ag+ ions and subsequent formation of colloidal Ag nanoparticles take place when an aqueous solution of a mixture of AgClO4, sodium dodecylsulfate (SDS) and benzophenone (BP) is irradiated with near-UV light. In this study, the mechanism and kinetics of the reaction have been studied by means of nanosecond laser flash photolysis, time-resolved emission spectroscopy and also steady-state photolysis. Benzophenone ketyl radial (BPK) is formed by the hydrogen abstraction reaction of the benzophenone triplet (BPT) from SDS, which reduces Ag+ ions. It is found that the yield of colloidal Ag nanoparticle formation decreases remarkably with increasing concentration of Ag+ ions, indicating the efficient quenching process of BPT by Ag+ ions. Rate constants for the oxidation of BPK as well as the quenching of BPT by Ag+ ions in SDS micellar solution are considerably larger than those expected in the bulk solution, reflecting that Ag+ ions and BP molecules are concentrated in the SDS micelles. The rate of colloidal Ag nanoparticle formation, VAg, and BP photobleach, VBP, under steady-state irradiation with near-UV light (λ = 365 nm) were evaluated and the dependence of VAg and VBP on the concentration of Ag+ ions is interpreted quantitatively in terms of rate constants estimated by laser flash photolysis.
56 citations
TL;DR: The catalytic hydrodehalogenation reaction using molecular hydrogen and Pd/C has been revisited and it is shown that the speed of removal of halogen increases with increasing electronegativity I < Br < Cl.
Abstract: The catalytic hydrodehalogenation reaction using molecular hydrogen and Pd/C has been revisited. It is shown that the speed of removal of halogen increases with increasing electronegativity I < Br < Cl. Nevertheless, selective dehydrohalogenation in compounds containing other reducible functions can be achieved only with iodine and not with bromine or chlorine. Selective deiodination of iodobenzophenone could be accomplished without reducing the carbonyl group. Hydrogenolysis of azidoiodoaromatic compounds to the corresponding azido compounds is high yielding. This selectivity was exploited for the labeling of benzophenone- and azido-containing compounds by deuterium and tritium.
55 citations
TL;DR: The results of these studies suggest that most of the benzophenone features found in the natural product are important for obtaining potent PKC inhibitory compounds, however, several modifications were found to lead to selective inhibitors of the related enzyme protein kinase A (PKA).
Abstract: A series of analogues of the protein kinase C (PKC) inhibitory natural product balanol which bear modified benzophenone subunits are described. The analogues were designed with the goal of uncovering structure-activity features that could be used in the development of PKC inhibitors with a reduced polar character compared to balanol itself. The results of these studies suggest that most of the benzophenone features found in the natural product are important for obtaining potent PKC inhibitory compounds. However, several modifications were found to lead to selective inhibitors of the related enzyme protein kinase A (PKA), and several specific modifications to the polar structural elements of the benzophenone were found to provide potent PKC inhibitors. In particular, it was found that replacement of the benzophenone carboxylate with bioisosteric equivalents could lead to potent analogues. Further, a tolerance for lipophilic substituents on the terminal benzophenone ring was uncovered. These results are discussed in light of recently available structural information for PKA.
55 citations
TL;DR: In this article, the X-ray crystal structures of RuCl2(dcypb)(CO) and RuCl3(CO)(PPh3)2(DMF) were reported.
49 citations
TL;DR: The results are indicative of two competitive mechanisms using BzO as the photosensitizer, instead of singlet oxygen addition and electron transfer, and Superoxide anion is suggested to play a crucial role in this oxidative radical pathway.
Abstract: Two different photosensitizers, 9,10-dicyanoanthracene (DCA) and benzophenone (BzO) or a silica bound derivative (BzO-Si) have been compared for the photooxidation of di-n-butyl sulfide and di-n-butyl disulfide. With either photosensitizer, sulfide photooxidation in acetonitrile leads very efficiently to sulfoxide, with sulfone and disulfides as by-products. Although an electron transfer mechanism has previously been established starting with DCA, our results are indicative of two competitive mechanisms using BzO as the photo sensitizer, instead of singlet oxygen addition and electron transfer. The more sluggish photooxidation of disulfides leads to a complex mixture of products, among which n-butyl butanethiosulfonate and strong acids (alkylsulfonic and sulfuric) are the major ones. The relative ratio thiosulfonate : acids depends, among other factors, on the medium polarity with acid formation favored starting with BzO or BzO-Si in a methanol-water mixture. An electron transfer mechanism only can account for the observed products. Superoxide anion, the formation of which is much easier starting from BzO than from DCA, is suggested to play a crucial role in this oxidative radical pathway. Starting from disulfides, grafted benzophenone is more efficient for acid formation than its soluble counterpart. As this photosensitizer can easily be recycled, an easy and smooth way to acid formation is thus available, provided that the reaction solvent is properly chosen.
48 citations
TL;DR: In this article, the authors compared two heterogeneous systems based on benzophenone (BP) and TiO 2 rutile powders using Raman and IR spectroscopy and showed that BP molecules form hydrogen bonds with the TiO surface active centers (Ti-OH) via phenyl ring π-electron systems.
47 citations
TL;DR: Semicarbazone of benzophenone single crystals have been grown by slow evaporation solution growth technique in this article using XRD, melting point, FT-IR and UV-Vis spectra analyses.
45 citations
TL;DR: In this article, a versatile synthesis of pyrazoles from aryl benzophenone hydrazones was demonstrated with a variety of 1,3-bifunctional substrates under acidic conditions.
TL;DR: In this article, the photonitiated cationic polymerization of cyclohexene oxide with N-phenacyl-N, N-dimethylanilinium hexafluoroantimonate (PDA+SBF - b ) and a polynuclear aromatic compound, such as perylene, anthracene or phenothiazine, or an aromatic carbonyl compound such as benzophenone or thioxanthone, was studied at λ inc > 340 nm.
Abstract: The photonitiated cationic polymerization of cyclohexene oxide with N-phenacyl-N,N-dimethylanilinium hexafluoroantimonate (PDA+SBF - b ) and a polynuclear aromatic compound, such as perylene, anthracene or phenothiazine, or an aromatic carbonyl compound, such as benzophenone or thioxanthone, was studied at λ inc > 340 nm. All the aromatic sensitizers except benzophenone and thioxanthone are effective in initiating the polymerization at at wavelengths where PDA + SbF - 6 is transparent. An initiation mechanism is iproposed that involes electron transfer from the excited sensitizer to PDA + SbF - 6 .
TL;DR: A series of adducts formed by the interaction of trimeric perfluoro-ortho-phenylene mercury (2) with various organic carbonyls including acetaldehyde, acetone, acetophenone, and benzophenone have been characterized in this article.
TL;DR: In this paper, the reaction of O-pentafluorobenzoyloximes of olefinic ketones with a catalytic amount of Pd(PPh 3 ) 4 and triethylamine in dimethylformamide (DMF) affords nitrogen-containing heterocycles, such as pyrroles, pyridines, isoquinolines, spiro-imines, and aza-azulenes.
Abstract: Electrophilic amination of Grignard reagents is accomplished by using O-sulfonyl- oximes of benzophenone derivatives. In the presence of a catalytic amount of CuCN, O-sul- fonyloxime of 4,4'-bis(trifluoromethyl)benzophenone reacts with alkyl Grignard reagents in tetrahydrofuran (THF) and hexamethylphosphoramide (HMPA), yielding primary alkyl- amines by successive hydrolysis of the resulting N-alkylimines. Arylamines are also prepared as well as alkylamines by treating O-sulfonyloxime of 3,3',5,5'-tetrakis(trifluoromethyl)- benzophenone in toluene-ether with Grignard reagents. Various cyclic imines are synthesized by palladium-catalyzed cyclization of olefinic oxime derivatives. That is, the reaction of O-pentafluorobenzoyloximes of olefinic ketones with a catalytic amount of Pd(PPh 3 ) 4 and triethylamine in dimethylformamide (DMF) affords nitrogen-containing heterocycles, such as pyrroles, pyridines, isoquinolines, spiro- imines, and aza-azulenes. This reaction proceeds via the initial formation of alkylidene- aminopalladium species generated by oxidative addition of oximes to Pd(0), and the succes- sive intramolecular Heck-type amination occurs on the olefinic moiety.
TL;DR: In this article, a perbenzylated derivative of balanol's highly functionalized benzophenone fragment is reported employing a regioselective Heck reaction as the key step for the connection of the two aromatic rings.
TL;DR: Two benzophenone O-arabinosides were isolated from the methanol extract of the herb of Hypericum annulatum and a chromone, 5,7-dihydroxy-3-methylchromone, which is encountered in a plant source for the first time.
TL;DR: Ketoprofen, suprofen and tiaprofenic acid are arylpropionic anti‐inflammatories and their chemical structures share the same elements as the benzoyl radical and the tiophene ring.
Abstract: Background: Ketoprofen, suprofen and tiaprofenic acid are arylpropionic anti-inflammatories. Their chemical structures share the same elements as the benzoyl radical and the tiophene ring. We experienced nine cases of ketoprofen photoallergy, seven cases of suprofen photoallergy and three cases of tiaprofenic photoallergy.
Purpose: To find the key structure of photosensitivity and photocross-reactivity to ketoprofen, suprofen and tiaprofenic acid.
Methods: Three animals were tested for phototoxicity and six animals for the photosensitization potentials of ketoprofen, suprofen, tiaprofenic acid and benzophenone, and the photocross-reactivity of the above chemicals. Test substances were applied symmetrically on both sides of the animals' backs. The animals were irradiated with 180 mJ/cm2 UVB (½ MED) and 10 J/cm2 UVA on the left side. The reactions were read on days 2, 3 and 4. The photosensitization potentials of ketoprofen, suprofen, tiaprofenic acid and benzophenone were determined using the Adjuvant-Strip method. Six animals were assigned to each test group and to a control group.
Results: Ketoprofen, suprofen, tiaprofenic acid and propionic acid showed negative reactions with the phototoxic test. Benzophenone showed phototoxic reactions to 40% acetone (ac.), 20% ac. and 10% ac. Therefore, we used 5% aq. benzophenone with the photosensitization test. Ketoprofen was the strongest photosensitizer (6/6) and showed photocross-reactivities to suprofen (2/6), tiaprofenic acid (3/6) and benzophenone (6/6). Suprofen was a strong photosensitizer (4/6) and showed photocross-reactivities to ketoprofen (1/4) and tiaprofenic acid (2/4), but not to benzophenone. Tiaprofenic acid was also a photosensitizer (2/6) but showed a photocross-reactivity only to benzophenone (2/2). Benzophenone was also the strongest photosensitizer (6/6), but did not photocross-react to the above three chemicals.
Conclusion: From the test results, it appears that benzoyl radical is the key structure for photosensitivity and the photocross-reactivity of ketoprofen, suprofen and tiaprofenic acid. The whole structure of benzophenone was needed to induce photosensitization of benzophenone. The animals that were photosensitized from the entire structure of benzophenone did not photocross-react to ketoprofen, suprofen or tiaprofenic acid.
TL;DR: The inherent efficiency of the N-spiro C2-symmetric chiral quaternary ammonium salt has been evaluated in the representative organic-aqueous liquid-liquid phase-transfer benzylation and allylation of glycine tert-butyl ester benzophenone Schiff base.
Abstract: The inherent efficiency of the N-spiro C2-symmetric chiral quaternary ammonium salt (S,S)-3 [(S,S)-β-Np-NAS-Br] has been evaluated in the representative organic-aqueous liquid-liquid phase-transfer benzylation and allylation of glycine tert-butyl ester benzophenone Schiff base (1). This revealed the practical conditions for the asymmetric synthesis of both natural and unnatural α-amino acids, whose usefulness was demonstrated by the formal enantioselective synthesis of antibiotic L-azatyrosine.
TL;DR: In this paper, the first experiments for preparing dye-labeled latex particles by the emulsion copolymerization of a 4/1 (w/w) mixture of vinyl acetate-butylacrylate (VAc-BA) were described.
Abstract: This article describes our first experiments for preparing dye-labeled latex particles by the emulsion copolymerization of a 4/1 (w/w) mixture of vinyl acetate-butylacrylate (VAc-BA). We discuss the synthesis of acrylate derivatives of phenanthrene, anthracene, and pyrene [9-acryloxymethyl phenanthrene (7), 9-acryloxymethyl-10-methyl anthracene (8), and 1-acryloxymethyl pyrene (10)] and an allyl ether derivative of anthracene [9-allyoxymethyl-10-methyl anthracene (9)]. Although the phenanthrene derivative 7 gave latex particles with high monomer conversion and good dye incorporation, the pyrene acrylate and both anthracene comonomers strongly inhibited the free-radical reaction. To assist our search for a dye that would serve as a useful energy acceptor for phenanthrene and without suppressing VAc-BA polymerization, we also examined batch emulsion polymerization in the presence of a variety of dye derivatives—substituted anthracenes, acridines, a coumarin, and two benzophenone derivatives. All of the anthracene derivatives, as well as acridine, strongly inhibited monomer polymerization. The coumarin dye 7-hydroxy-4-methyl coumarin (22) that had only limited solubility allowed more than 90% monomer conversion. Most promising were 2-hydroxy-5-methyl benzophenone (23) and 4-N,N-dimethylamino benzophenone (24) that at 1 mol % in the monomer mixture permitted virtually quantitative monomer conversion to latex. 4′-Dimethylamino-2-acryloxy-5-methyl benzophenone (25) copolymerized well with the VAc-BA mixture, yielding latex particles in high yield and with a narrow size distribution. These dyes appear to be useful acceptor dyes for energy-transfer experiments with phenanthrene. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 1594–1607, 2002
TL;DR: With an IC(50) value of 190 nM the 4,4'-derivative is the first small monocyclic STS inhibitor coming close to the potency of the steroidal standard estrone sulfamate.
TL;DR: In this paper, the X-ray data showed that the numerical values of the measured Y−O lengths decrease in the order THF > benzophenone > methyl methacrylate > e-caprolactone > hexamethylphosphoramide > E-cap-rolactam > 1-methyl-2-pyrrolidinone > N,N-N-dimethylpropyleneurea.
TL;DR: In this paper, the formation of inclusion complexes of β-phenylpropiophenone and benzophenone with p-tert-butylcalix, [6] and [8]arenes (powdered solid samples) was studied with the use of diffuse reflectance techniques.
Abstract: The formation of inclusion complexes of β-phenylpropiophenone and benzophenone with p-tert-butylcalix[4], [6] and [8]arenes (powdered solid samples) was studied with the use of diffuse reflectance techniques. Experimental evidence was obtained for inclusion in all cases. The benzophenone n → π* absorption band exhibits hypsochromic shifts with an increase of the calixarene ring aperture, providing evidence for an increase in cavity polarity. β-Phenylpropiophenone exhibits strong room temperature phosphorescence in contrast to its solution behaviour, and this is a clear evidence for the inclusion of this probe within the calixarene molecules. Calix[4]arene and calix[8]arene provide a more rigid environment to β-phenylpropiophenone whereas calix[6]arene appears to be more flexible. Transient absorption spectra of inclusion complexes with
benzophenone (1 : 1 mol : mol, excited at 355 nm) show major triplet formation in the calix[4]arene case, while the ketyl radical of benzophenone is formed in the calix[6]arene case and is predominant in the calix[8]arene case. Phenoxyl radical transient absorption also becomes evident in the last two cases. For β-phenylpropiophenone (1 : 1 mol : mol) phenoxyl radicals are formed but no evidence was found for triplet or ketyl radical formation of this ketone in the calix[4]arene case. However, strong support for the ketyl radical of the aryl alkyl ketone was found for calix[6]arene and calix[8]arene inclusion complexes.
TL;DR: A positive working photosensitive alicyclic polyimide precursor based on poly(amic acid tert-butyldimethylsilylester) (3) and 2,3,4-tris[2-diazo-1-(2H)-naphthalenone-4-sulfonyloxy]benzophenone as mentioned in this paper.
Abstract: A new positive working photosensitive alicyclic polyimide precursor based on poly(amic acid tert-butyldimethylsilylester) (3) and 2,3,4-tris[2-diazo-1-(2H)-naphthalenone-4-sulfonyloxy]benzophenone ...
TL;DR: The triplet state of 4-methoxybenzophenone (4-MBP) has been investigated by laser flash photolysis and emission techniques in several solvents and shows in aqueous solutions a transient absorption spectrum with lambda(max) at 450 and 680 nm, which can be attributed to a T1 (pi,pi*) state.
Abstract: The triplet state of 4-methoxybenzophenone (4-MBP) has been investigated by laser flash photolysis and emission techniques in several solvents. In non-polar cyclohexane, 4-MBP triplet has an (n,π*) configuration with the typical triplet–triplet absorption spectrum of benzophenone (λmaxca. 525 nm). However, due to the proximity of the two lowest triplet states of different configuration, some unusual features are observed in polar solvents. Thus, 4-MBP shows in aqueous solutions a transient absorption spectrum with λmax at 450 and 680 nm, which can be attributed to a T1
(π,π*) state. Further, transient absorption spectra due to T1
(n,π*) and T2
(π,π*) being simultaneously populated are observed upon laser excitation of 4-MBP in polar solvents such as acetonitrile or methanol. The triplet
state inversion (n,π* to π,π*) is also detected by the measurement of triplet quenching rate constants by 1,4-cyclohexadiene (a good hydrogen donor) in acetonitrile and water (kHca. 2 × 108 and 5 × 105 M−1 s−1, respectively) and by the determination of room-temperature phosphorescence (the emission quantum yield at room-temperature decreases from 0.004 in acetonitrile to less than 1 × 10−6 in water). Further, the energy of the 4-MBP triplet state is ca. 288 kJ mol−1 both in polar and non-polar organic solvents, while in water it drops to 275 kJ mol−1. The photophysical properties of 4-MBP are compared with those of 4-aminobenzophenone (4-ABP), which also possesses an electron-donating group. In polar organic solvents such as acetonitrile, the transient absorption
spectrum and the quenching rate constant of hydrogen abstraction for triplet 4-ABP are practically the same as those obtained for 4-MBP in aqueous solutions. On the other hand, a small T2
(π,π*) contribution is observed in the triplet–triplet absorption spectrum of 4-ABP in cyclohexane.
TL;DR: The developed procedure has been successfully utilized for the estimation of thorium content of pure Rare earth chloride solution collected from Indian Rare Earths (IRE) Limited, Alwaye.
TL;DR: In this paper, the photocuring rates of acrylate monomers initiated by abstraction type photoinitiators (benzophenone, isopropylthioxanthone, and N-methylmaleimide) and a series of structurally different tertiary amine combinations are reported.
Abstract: The photocuring rates of acrylate monomers initiated by abstraction type photoinitiators (benzophenone, isopropylthioxanthone, and N-methylmaleimide) and a series of structurally different tertiary amine combinations are reported. Photo-DSC results confirm that transferable hydrogens on tertiary amines are essential for efficient acrylate polymerization. Laser flash photolysis experiments were carried out to define the electron/proton transfer reactions which occur between excited triplet states of the photoinitiators and tertiary amines. In the case of N-methylmaleimide, an intermediate radical anion was detected for amines with no readily transferable proton. This confirms that the photoreduction of the triplet state of N-substituted maleimides by tertiary amines occurs by an electron/proton transfer when the tertiary amine electron donor has a transferable proton.
TL;DR: In this article, principal component analysis with self-modeling based on the van't Hoff equation constraint was applied to a set of benzophenone luminescence spectra from degassed carbon tetrachloride solutions in the 14.7−88.5 °C range.
Abstract: Principal component analysis with self-modeling based on the van't Hoff equation constraint was applied to a set of benzophenone luminescence spectra from degassed carbon tetrachloride solutions in the 14.7−88.5 °C range. This analysis differs from an earlier treatment in that it was preceded by compensation of the spectra for differential broadening with increasing T. A set of Gaussians was derived as previously described [Saltiel, J.; Sears, D. F., Jr.; Turek, A. M. J. Phys. Chem. A 2001, 105, 7569−7578] that, on convolution with the spectrum for each corresponding T, creates a uniformly broadened spectral set. Significant improvements in the accuracy of the resolved delayed fluorescence and phosphorescence spectra lead to a reliable comparison between prompt and delayed fluorescence spectra that confirms the conclusion that the short S1 lifetime prevents full relaxation of emitting benzophenone singlets. The enthalpy difference for the T1/S1 equilibrium, 5.50 ± 0.06 kcal/mol, agrees with the energy dif...
TL;DR: In this article, photo-induced graft filling polymerization was used to obtain a benzene permselectivity for benzene/cyclohexane mixture (50/50 v/v) on pervaporation.
TL;DR: Results imply that peroxyl radicals are responsible for the photooxidation by the group B ketones, which are formed by alpha cleavage of the triplet ketone and subsequent O(2) trapping of the carbon-centered radicals.
Abstract: The photooxidation of 2‘-deoxyguanosine (dG) and its derivative 8-oxo-7,8-dihydro-2‘-deoxyguanosine (8-oxodG) by a series of acetophenones (AP-X) and benzophenone (BP) has been studied.The favorable absorption characteristics of the benzoyl chromophore enables time-resolved spectroscopy of the triplet ketones to assess their quenching kinetics by dG and 8-oxodG. Whereas the photolysis of acetophenone (AP), 2-acetoxyacetophenone (AP-OAc), and benzophenone (BP) does not produce radicals (group A ketones), the oxymethyl-substituted derivatives 2-hydroxyacetophenone (AP-OH) and 2-tert-butoxyacetophenone (AP-OtBu) lead to carbon-centered radicals by α cleavage (group B ketones). For the latter ketones, this was confirmed by EPR studies with the spin trap 5,5-dimethylpyrroline N-oxide (DMPO) and by their triplet lifetimes that were shorter than those for the unsubstituted acetophenone. Both groups of ketones photooxidize dG and 8-oxodG; the oxidation products are spiroiminodihydantoin and guanidine-releasing pr...
TL;DR: In this paper, the surface-mediated hydride-transfer reaction of 1,4-cyclohexadiene with triphenylmethylium induced by two silicas, an alumina, and an aluminosilicate as solid acid catalyst, respectively, has been kinetically studied as a function of the polarity of the surrounding solvent.
Abstract: The surface-mediated hydride-transfer reaction of 1,4-cyclohexadiene with triphenylmethylium induced by two silicas, an alumina, and an aluminosilicate as solid acid catalyst, respectively, has been kinetically studied as a function of the polarity of the surrounding solvent. The specific rate constants k‘ have been determined in 10 different solvents. Generally, k‘ decreases with increasing polarity of the solvent. Kamlet−Taft's α (hydrogen-bond acidity) and π* (dipolarity/polarizability) parameters of the solid acid/solvent interface have been determined for alumina and aluminosilicate in various solvents. Fe(phen)2(CN)2 [cis-dicyanobis(1,10-phenanthroline)iron(II), (1)] and Michler's ketone [4,4‘-bis(N,N-dimethylamino)benzophenone, (2)] were used as solvatochromic surface polarity indicators. The UV/vis spectra of the two surface polarity indicators 1 and 2 adsorbed on solid acid catalysts from the solvents were measured by the reflection mode and the UV/vis absorption maxima were used to calculate the...