Benzene dimer substituted

While benzene and substituted benzenes usually do not dimerize, pyridine derivatives undergo [4+4]photodimerizations432) (4.29). 

Table 5. Binding Energies Ei, for the Methyl-Substituted Benzene Dimer Cations Based on Application of the Generic Standard Hydrocarbon Model to the Radiative Association Kinetic Data. I obs is the Efficiency per Collision of Radiative...

A number of computational studies have looked at the benzene dimer with multiple substituents, such as 78 and 79 and 80. All of them show an additivity effect (i.e., increased binding) with each new substituent, regardless of whether the substituent is an EWG or an EDG, and regardless of whether the substitution is on one ring or on both rings. This additivity is not seen in the T-shape configuration. ... 

Ringer, A. L. Sherrill, C. D. Substituent effects in sandwich configurations of multiply substituted benzene dimers are not solely governed by electrostatic control, J. Am. Chem. Soc. 2009,131,4574-4575. 

Hohenstein, E. G., Duan, J., and Sherrill, C. D. (2011a). Origin of the surprising enhancement of electrostatic energies by electron-donating substituents in substituted sandwich benzene dimers,/ Am. Chem. Soc. 133, pp. 13244-13247, doi 10.1021/ja204294q. 

EFPl and general EFP methods were extensively used to investigate non-covalent interactions in clusters and liquids. For example, EFPl water potential was used to characterize structures and binding energies in water clusters and liquid water [31-33]. General EFP method was employed in studies of alcohol-water clusters and mixtures [34-35] and solvation of ions [36-37], benzene and substituted benzene dimers [14, 38], water-benzene complexes [39], intermolecular interactions in st3mene clusters [40] and DNA base pairs [5,41]. 

Henson, GV Hartland, VA Venturo, RA Hertz, PM Felker. Stimulated Raman spectroscopy in the Vi region of isotopically substituted benzene dimers Evidence for symmetrically inequivalent benzene moieties. Chem Phys Lett 176 91-98, 1991. 

Lee, C., Kim, D., Jurecka, R, Tarakeshwar, R, Hobza, R, Kim, K. S. (2007). Understanding of assembly phenomena by aromatic-aromatic interactions Benzene dimer and the substituted systems. The Journal of Physical Chemistry. A, 111, 3446-3457. 

AEyl chloride reacts with sodamide in Hquid ammonia to produce benzene when sodamide is in excess, hexadiene dimer is the principal product, with some trimer and tetramer (C24, six double bonds). AEylation at carbon atoms alpha to polar groups is used in the preparation of a-aEyl-substituted ketones and nittiles. Preparation of P-diketone derivatives, methionic acid derivatives, and malonic ester, cyanoacetic ester, and P-keto-ester derivatives, etc, involving substitution on an alpha carbon between two polar carbonyl groups, is particularly facEe. 

As shown, ia the case of chlotination of aEyl chloride, the resonance states of the chloroaEyl radical iatermediates are not symmetrical and their propagation reactions lead to the two different dichloropropene isomers ia an approximate 10 90 ratio (26). In addition, similar reactions result ia further substitution and addition with products such as trichloropropanes, trichloropropenes, tetrachloropropanes, etc ia diminisbing amounts. Propylene dimerization products such as 1,5-hexadiene, benzene, 1-chloropropane, 2-chloropropane, high boiling tars, and coke are also produced ia smaE amounts. 

Xu and Li (1989) investigated H — CIDNP spectra of fifteen substituted benzene-diazonium ions during reduction with NaBH4. The spectra are consistent with a mechanism in which the first step is the addition of a hydride ion to the diazonium ion. The diazene formed (Ar - N2 - H) is assumed to dimerize and disproportionate into a radical pair [Ar-N-NH2 N = N — Ar] which loses one equivalent of N2 yielding [Ar—N —NH2 Ar] and recombines to give the diarylhydrazine. A proportion of the aryl radicals escape and form the hydro-de-diazoniation product. 

Alkyl-substituted benzenes are oxidized both on the benzene ring and on the side chain. Additionally, some dimerization occurs.36 Alkylbenzenes containing linear alkyl groups are oxidized preferentially at the side chain33 nearest the benzene ring for example, ethylbenzene oxidizes first to 1-phenyl ethanol and then to acetophenone.36... 

The stability of o-sulfonylbenzonitrile oxides and their thiophene analogs probably depends on electronic factors. The same factors do not prevent dimerization, as can be seen from data concerning several differently substituted nitrile oxides of the thiophene series (103). Sterically stabilized 3-thiophenecarbonitrile oxides 18 (R = R1 = R2 = Me R = R2 = Me, R1 = i -Pr), when boiled in benzene or toluene, isomerized to isocyanates (isolated as ureas on reaction with aniline) while nitrile oxides 18 with electron-withdrawing substituents (R1 and/or R2 = SOiMe, Br) dimerized to form furoxans 19. 

In 1988 Heinze and Burton reported a facile synthesis of various a,p,P-trifluorostyrenes.15 These trifluorostyrene compounds were reported to be unstable to cyclodimerization at room temperature when stored neat, especially the compounds that were /lura-substituted with electron-donating substituents. They described the preparation of one compound, l,4-bis(trifluorovinyl)benzene with the observation that the material gelled when allowed to stand neat overnight. They offered the explanation that the gel was a polymer network connected with flnorinated cyclobutanes. Burton later went on to utilize this dimerization reaction for the cross-linking of polyimide thermoplastics.16... 

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