1520-40-7

Upstream product

• 74-87-3 methylene chloride 
• 1081-75-0 1,3-diphenylpropane 
• 16619-32-2 1-(3-methyl-phenyl)-3-phenyl-2-propen-1-one 
• 100-52-7 benzaldehyde 
• 585-74-0 3-Methylacetophenone 

Relevant academic research and scientific papers

Effects of substituents on NMR chemical shifts and mass fragmentation patterns of 1-aryl-3-phenylpropanes

The 1H and 13C chemical shifts and the mass spectral fragmentation patterns of 1-aryl-3-phenylpropanes with m- or p-substituents (H, NO2, Br, Cl, OCH3, CH3) were studied. The electronic effects of the substi-tuents seemed to be transmitted by the through-space as well as by a through-bond mechanism, resulting in an inverse correlation in the plot of the chemical shift values of i-C vs. the Hammett σ values. The mass spectra showed the substituted benzyl fragments as the base peaks when the substituents were electron donating, whereas the benzyl fragment was observed as the base peaks with the electron-withdrawing substituents.

Cation-π interactions in the gas phase methylation of α,ωdiphenylalkanes

The methylation of α,ω-diphenylalkanes (C6H5(CH2)nC6H5 , n = 1-6) has been performed in the gas phase using Me2Cl+ ions as alkylating species and toluene as reference substrate. Both in radiolytic experiments at atmospheric pressure and in FT-ICR measurements at 10-8 Torr, the selected diphenylalkanes reacted faster than toluene, the highest reactivity displayed by 1,3-diphenylpropane. The kinetic pattern of the reaction, conforming to the established scheme of an electrophilic alkylation reaction, is consistent with a rate-determining formation of the σ-complex intermediate, at variance with the tert-butylation of the same series of compounds by Me3C+ ions, occurring at the collisional encounter rate. The kinetic features are explained by a marked effect due to the presence of the second aryl ring, providing additional stabilization of both the ion-neutral collision complex and the σ complex with respect to toluene. Both factors contribute to the δEa of ca. 8 kcal mol-1 for the competition of 1,3-diphenylpropane and toluene found in the temperature dependence study of the Me2Cl+ reaction.

The gas-phase reactivity of p-Me3Si-substituted 1,3-diphenylpropane towards charged electrophiles: Intra- and interannular hydrogen migrations

The gas-phase reaction of p-Me3SiC6H4(CH2)3C6H5 (p-TSDPP) with gaseous cations, including C2H5+, Me2Cl+ and DCO+, has been studied in the pressure range from 10-8 to 103 Torr by Fourier-transform ion cyclotron resonance (FT-ICR) and by the radiolytic technique. The protonated or alkylated intermediates undergo intramolecular migration and intermolecular transfer of protons and/or Me3Si+. The results underline the role of the spectator ring in providing internal solvation to an arenium moiety, as evidenced by the noticeable stability towards Me3Si loss with respect to a single-ring model substrate, p-Me3SiC6H4Me (p-TST), upon reaction with the same gaseous ions. The extent of the alkylation route relative to the alkyldesilylation processes, measured as a function of the arenium ion lifetime, permits derivation of the rate constant for the conversion by proton transfer of the originally formed arenium ions to ipso-silylated isomers (k(i)). The estimated values of k(i(p-TST)) = 5 x 109 s-1 and k(i(p-TSDPP)) = 2 x 108 s-1 at 120°C suggest that interannular H shifts are faster than ring-to-ring H transfer, in agreement with previous evidence from tert-butylated arenium ions. The reactivity of [Me3Si=arene]+ adducts, adequately described by the Wheland σ-complex model, does not exclude the intermediacy of an ion-neutral noncovalent complex.