429677-33-8

Upstream product

• 20359-74-4 (4-methoxyphenyl)phenyldiazomethane 
• 720-44-5 1-(4-methoxyphenyl)-1-phenylmethanol 
• 38513-66-5 (phenyl)(p-methoxyphenyl)methanol acetate 
• 6731-11-9 4-methoxybenzhydryl chloride 
• 1580541-39-4 4-methoxybenzhydryl chloroacetate 
• 1580541-43-0 4-methoxybenzhydryl bromoacetate 
• 1580541-35-0 4-methoxybenzhydryl fluoroacetate 
• 1580541-49-6 4-methoxybenzhydryl dichloroacetate 
• 1580541-54-3 4-methoxybenzhydryl formate 
• 38377-38-7 4-fluorophenyl chloroformate 
• 7693-41-6 4-methoxyphenylchloroformate 
• 937-62-2 p-tolyl chloroformate 
• 116664-89-2 (4-methoxyphenyl)-phenylmethyl 4-cyanophenyl ether 

Downstream Products

• 834-14-0 p-benzylanizole 
• 28927-31-3 trimethylsilanylium 
• 136430-67-6 C₄H₁₁Si⁽¹⁺⁾ 
• 136430-68-7 C₅H₁₃Si⁽¹⁺⁾ 
• 128709-42-2 C₉H₂₁Si⁽¹⁺⁾ 
• 33335-65-8 C₅H₁₅OSi₂⁽¹⁺⁾ 
• 44564-80-9 Triethylsilyl cation 
• 60604-28-6 C₁₂H₂₇Si⁽¹⁺⁾ 
• 148354-29-4 C₉H₂₇Si₄⁽¹⁺⁾ 
• 32825-42-6 dimethyl-phenyl-silanylium 
• 139732-72-2 phenylsilyl cation 
• 119946-89-3 C₇H₉Si⁽¹⁺⁾ 
• 29996-90-5 triphenylsilanylium 

Relevant academic research and scientific papers

Solvolytic Behavior of Aryl and Alkyl Carbonates. Impact of the Intrinsic Barrier on Relative Reactivities of Leaving Groups

The effect of negative hyperconjugation on the solvolytic behavior of carbonate diesters has been investigated kinetically by applying the LFER equation log k = sf(Ef + Nf). The observation that carbonate diesters solvolyze faster than the corresponding carboxylates and that the enhancement of aromatic carbonates is more pronounced indicates that the negative hyperconjugation and π-resonance within the carboxylate moiety is operative in TS. The plots of ΔG? vs approximated ΔrG° for solvolysis of benzhydryl aryl/alkyl carbonates and benzhydryl carboxylates reveal that a given carbonate solvolyzes over the higher Marcus intrinsic barrier and over the earlier transition state than carboxylate that produces an anion of similar stability. Due to the lag in development of the electronic effects along the reaction coordinate, the impact of the intrinsic barrier on solvolytic behavior of carbonates is more important than in the case of carboxylates and phenolates. Consequently, the solvolytic reaction constants (sf) are generally lower for carbonates than for carboxylates. Because of considerable lower reaction constants of carbonates, an inversion of relative reactivities between aryl/alkyl carbonate and another leaving group of similar nucleofugality (Nf) may occur if the electrofuge moiety of a substrate is switched.

Solvolytic Behavior of Aliphatic Carboxylates

The leaving group abilities (nucleofugalities) of a series of aliphatic carboxylates have been obtained by determining the nucleofuge-specific parameters (Nf and sf) from solvolysis rate constants of X,Y-substituted benzhydryl carboxylates in a series of aqueous ethanol mixtures by applyication of the linear free energy relationship (LFER) equation: log k = sf (Ef + Nf). These values can be employed to compare reactivities of carboxylates with those of other leaving groups previously included in the nucleofugality scale, and also to estimate the solvolysis rates of various carboxylates. It is confirmed that the inductive effect is the most important variable governing the reactivities of halogenated carboxylates in solution. Moreover, both the Hammett correlation and the solvolytic activation parameters have revealed a strong influence of the inductive effect on the nucleofugality of alkyl-substituted carboxylates. The reaction constants (sf) indicate that carboxylate substrates with weaker leaving groups solvolyze via later, more carbocation-like, transition states, which is in accord with the Hammond postulate. In addition, due to the weaker demand for solvation of transition states that produce more strongly stabilized benzhydrylium ions, in which more efficient charge delocalization occurs, the reaction constants (sf) obtained with most of the leaving groups investigated here increase as the polarity of the solvent decreases.

Solvent nucleophilicities of hexafluoroisopropanol/water mixtures

First-order rate constants k1 for the trapping of various donor- and acceptor-substituted benzhydrylium ions in mixtures of 1,1,1,3,3,3- hexafluoro-2-propanol (HFIP) and water ranging from 50 to 99% HFIP (w/w) were determined by laser flash pho

Nucleofugality and nucleophilicity of fluoride in protic solvents

A series of p-substituted benzhydryl fluorides (diarylfluoromethanes) were prepared and subjected to solvolysis reactions, which were followed conductometrically. The observed first-order rate constants k1(25 °C) were found to follow the correlation equation log k1(25 °C) = sf(Nf + Ef), which allowed us to determine the nucleofuge-specific parameters Nf and sf for fluoride in different aqueous and alcoholic solvents. The rates of the reverse reactions were measured by generating benzhydrylium ions (diarylcarbenium ions) laser flash photolytically in various alcoholic and aqueous solvents in the presence of fluoride ions and monitoring the rate of consumption of the benzhydrylium ions by UV-vis spectroscopy. The resulting second-order rate constants k-1(20 °C) were substituted into the correlation equation log k-1 = sN(N + E) to derive the nucleophilicity parameters N and sN for fluoride in various protic solvents. Complete Gibbs energy profiles for the solvolysis reactions of benzhydryl fluorides are constructed.

Nucleophilic reactivities of tertiary alkylamines

The kinetics of the reactions of tertiary amines, triethylamine (1a), N-methylpyrrolidine (1b), N-methylpiperidine (1c), and N-methylmorpholine (1d) with benzhydrylium ions (Ar2CH+) have been studied in acetonitrile and dichlorometha

The role of aromatic radical cations and benzylic cations in the 2,4,6-triphenylpyrylium tetrafluoroborate photosensitized oxidation of ring-methoxylated benzyl alcohols in CH2Cl2 solution

A steady-state and laser flash photolysis (LFP) study of the TPPBF 4-photosensitized oxidation of ring-methoxylated benzyl alcohols has been carried out. Direct evidence on the involvement of intermediate benzyl alcohol radical cations and benzylic cations in these reactions has been provided through LFP experiments. The reactions lead to the formation of products (benzaldehydes, dibenzyl ethers, and diphenylmethanes) whose amounts and distributions are influenced by the number and relative position of the methoxy substituents. This behavior has been rationalized in terms of the interplay between the stabilities of benzyl alcohol radical cations and benzyl cations involved in these processes. A general mechanism for the TPPBF 4-photosensitized reactions of ring-methoxylated benzyl alcohols has been proposed, where the a-OH group of the parent substrate acts as the deprotonating base promoting α-C-H deprotonation of the benzyl alcohol radical cation (formed after electron transfer from the benzyl alcohol to TPP*) to give a benzyl radical and a protonated benzyl alcohol, precursor of the benzylic cation. This hypothesis is in contrast with previous studies, where formation of the benzyl cation was suggested to occur from the neutral benzyl alcohol through the Lewis acid action of excited TPP+ (TPP*).

The nature of the transition state in diarylmethyl cation - Nucleophile combination reactions as probed by secondary α-deuterium isotope effects

Transition-state structures for the carbocation-nucleophile combination reactions of (4-substituted-4′-methoxydiphenyl)methyl cations with water, chloride, and bromide ions in acetonitrile-water mixtures have been investigated by measuring the secondary α-deuterium kinetic and equilibrium isotope effects. Rate constants in the combination direction were measured with laser flash photolysis. Equilibrium constants were measured for the water reaction by a comparison method in moderately concentrated sulfuric acid solutions, for the bromide reaction via the observation of reversible combination, and for the chloride reaction from the ratio of the combination rate constant and the rate constant for the ionization of the diarylmethyl chloride product. The fraction of bond making in the transition state has been calculated as the ratio log (kinetic isotope effect):log (equilibrium isotope effect). For the water reaction, there is 50-65% bond making in the transition state; this is also true for cations that are many orders of magnitude less reactive. The same conclusions, 50-65% bond formation in the transition state independent of reactivity, have previously been made in corre-lations of log kw vs. log KR. Thus, two quite different measures of transition structure provide the same result. The kH:kD values for the halide combinations in 100% acetonitrile are within experimental error of unity. This is consistent with suggestions that these reactions are occurring with diffusional encounter as the rate-limiting step. Addition of water has a dramatic retarding effect on the halide reactions, with rate constants decreasing steadily with increased water content. Small inverse kinetic isotope effects are observed (in 20% acetonitrile:80% water) indicating that carbon-halogen bond formation is rate-limiting. Comparison of the kinetic and equilibrium isotope effects shows ～25 and ～40% bond formation in the transition states for the reactions with bromide and chloride, respectively.

Picosecond kinetic study of the dynamics for photoinduced homolysis and heterolysis in diphenylmethyl chloride

The kinetics of both the ions and radicals formed upon photolysis of diphenylmethyl chloride, (4-methoxyphenyl)phenylmethyl chloride, and bis(4-methoxyphenyl)methyl chloride in acetonitrile and propionitrile are examined by picosecond pump - probe spectroscopy. Both radical pairs and ion pairs are formed directly from a common excited state. In addition, the geminate radical pair decays by electron transfer to form either the contact ion pair or a covalent bond, as well as undergoes diffusional separation to free radicals.

Photo-heterolysis and -homolysis of substituted diphenylmethyl halides, acetates, and phenyl ethers in acetonitrile: Characterization of diphenylmethyl cations and radicals generated by 248-nm laser flash photolysis

Para-substituted diphenylmethyl halides, acetates, and ethers RPh(R′Ph)CH-X (R, R′ = CF3 to OCH3), upon photolysis with ～250-nm light in acetonitrile solutions, undergo homolysis and heterolysis of the C-X bond to give the radicals, RPh(R′Th)CH? (abbreviated as C?), and the cations, RPh(R′Ph)CH+ (C+). Whereas the quantum yields for homolysis (0.2-0.4) are rather independent of the nature of the substituent on the benzene ring, those for heterolysis increase with increasing electron-donator strength from ≤0.07 for CF3 to 0.3 for OMe. The cation:radical ratios are also dependent on the nucleofugal properties of X. For the halides, the observed heterolysis:homolysis ratios correlate with the pKa values of the conjugate acids HX and not with the electron affinities of X?. In acetonitrile, heterolysis is much less endothermic than homolysis. Homolysis and heterolysis can also be effected indirectly by reaction with triplet acetophenone (produced by 308-nm photolysis). Unless stabilized by one or more MeO, the cations decay predominantly by reaction with acetonitrile to give nitrilium ions. However, since this reaction is reversible (shown for the benzhydryl cation), the nitrilium ion contributes only to an insignificant degree to the formation of the final (cation-derived) products, which result from reaction with trace water (main product, benzhydryl alcohol; minor, benzhydrylacetamide). The rate constants for addition of C+ to CH3CN are in the range 3.5 × 105 to 3.8 × 107 s-1 for the cations with R = R′ = Me to R = H, R′ = CF3. The rate constants for reaction of C+ with halides (ion recombination) are ～2 × 1010 M-1 s-1 (diffusion control). The radicals C? disappear by dimerization and disproportionate, for which a complete mass balance has been achieved by product analysis for the case of the benzhydryl system. At laser-pulse powers > 10 mJ electronically excited radicals, C?*, are additionally formed in many cases, via absorption of a light quantum by ground-state C?.