23946-68-1

Upstream product

• 95-93-2 1,2,4,5-tetramethylbenzene 
• 108-67-8 1,3,5-trimethyl-benzene 
• 509-14-8 tetranitromethane 
• 108-88-3 toluene 
• 91-20-3 naphthalene 

Relevant academic research and scientific papers

A Simple Preparation of Diarylmethanes by Oxidative Friedel-Crafts Reaction of Methyl-Substituted Benzenes with o-Chloranil

The reaction of o-chloranil with some methyl-substituted benzenes at elevated temperature was found to be a simple and selective route toward diarylmethanes without need for prior preparation of benzyl halides.

Novel and efficient oxidative biaryl coupling reaction of alkylarenes using a hypervalent iodine(III) reagent

First facile and efficient oxidative coupling reaction of alkylarenes leading to alkylbiaryls using a combination of hypervalent iodine(III) reagent, phenyliodine(III) bis(trifluoroacetate) (PIFA), and BF3·Et2O has been developed.

Photochemical nitration by tetranitromethane. Part XXXIII. Adduct formation in the photochemical reactions of 1,2,4,5- and 1,2,3,5-tetramethylbenzene

The photolysis of the charge-transfer complex of tetranitromethane and 1,2,4,5-tetramethylbenzene in dichloromethane or acetonitrile gives the epimeric 1,3,4,6-tetramethyl-3-nitro-6-trinitromethylcyclohexa-1,4-dienes 8 and 9, in addition to products of nuclear nitration 12 and side-chain modification 10, 11, and 13-18. Similar reactions of 1,2,3,5-tetramethylbenzene gave trans-1,3,5,6-tetramethyl-6-nitro-3-trinitromethylcyclohexa-1,4-diene 30 and two isomeric 'double' adducts 31 and 32, in addition to products of nuclear nitration 27 and side-chain modification 26, 28 and 29. The eliminative rearrangements of adducts 8 and 30 to give re-aromatized products in acetonitrile or [2H3] acetonitrile and in [2H] chloroform are reported. The photolysis of the charge-transfer complexes of tetranitromethane with either 1,2,4,5-tetramethylbenzene or 1,2,3,5-tetramethylbenzene in 1,1,1,3,3,3-hexafluoropropan-2-ol (HFP) gives a marked increase in the yields of ring-nitration products 12 or 27, respectively, reactions presumed to proceed via a nitrosation-oxidation sequence. Reaction of 1,2,4,5-tetramethylbenzene with excess nitrogen dioxide in HFP also results in extensive ring nitration to give 12 and 2,3,5,6-tetramethyl-1,4-dinitrobenzene (25); the latter compound is seen as arising via the 2,3,5,6-tetramethyl-1,4-dinitrosobenzene (34). Similar reaction of 1,2,3,5-tetramethylbenzene gives ring-nitration product 27 as the major product. X-Ray crystal structures are reported for 2,4,6-trimethyl-1-(2′,2′,2′-trinitroethyl)benzene (26) and trans-1,3,5,6-tetramethyl-6-nitro-3-trinitromethyl-cyclohexa-1,4-diene (30). Acta Chemica Scandinavica 1996.

Direct Nitrosation of Aromatic Hydrocarbons and Ethers with the Electrophilic Nitrosonium Cation

Various polymethylbenzenes and anisoles are selectively nitrosated with the electrophilic nitrosonium salt NO(1+)BF4(1-) in good conversions and yields under mild conditions in which the conventional procedure (based on nitrile neutralization with strong acid) is ineffective.The reactivity patterns in acetonitrile deduced from the various time/conversions in Tables 2 and 3 indicate that aromatic nitrosation is distinctly different from those previously established for electrophilic aromatic nitration.The contrasting behavior of NO(1+) in aromatic nitrosation is ascribed to a rate-limiting deprotonation of the reversibly formed Wheland intermediate, which in the case of aromatic nitration with NO2(1+) occurs with no deuterium kinetic isotope effect.Aromatic nitroso derivatives (unlike the nitro counterpart) are excellent electron donors that are subject to a reversible one-electron oxidation at positive potentials significantly less than that of the parent polymethylbenzene or anisole.As a result, the series of nitrosobenzenes are also much better Broensted bases than the corresponding nitro derivatives, and this marked distinction, therefore, accounts for the large differentiation in the deprotonation rates of their respective conjugate acids (i.e.Wheland intermediates).

Thermal and Photochemical Nitration of Aromatic Hydrocarbons with Nitrogen Dioxide

Aromatic hydrocarbons (ArH) are readily nitrated by nitrogen dioxide (NO2) in dichloromethane at room temperature and below (in the dark).The red colors, transiently observed, arise from the metastable precursor complex NO3(1-), which is formed in the prior disproportionation of nitrogen dioxide induced by the aromatic donor (eq 7).The deliberate irradiation of the diagnostic (red) charge-transfer absorption band (hνCT) of NO3(1-) at low temperatures results directly in aromatic nitration, even at -78 deg C, where the thermal nitration is too slow to complete.The mechanism of the photochemical (charge-transfer) nitration is established by time-resolved laser spectroscopy to proceed via the aromatic cation radical (ArH.+) formed spontaneously upon the charge-transfer excitation of NO3(1-) in Scheme 1.The related thermal activation of NO3(1-) derives from the adiabatic electron transfer that produces the same radical pair as the reactive intermediate in Scheme 3.The close relationship between the thermal/photochemical nitrations with nitrogen dioxide and those conventionally carried out with nitric acid (in the presence of nitrous acid) is delineated by Scheme 4.

Time-resolved Spectroscopy and Charge-transfer Photochemistry of Aromatic EDA Complexes with X-Pyridinium Cations

Direct photoexcitation of 1: 1 aromatic EDA complexes with various N-substituted X-pyridinium cations (X = nitro, fluoro, methoxy and acetoxy) is achieved by the specific irradiation of their charge-transfer (CT) absorption bands.Time-resolved picosecond spectroscopy refers to charge-transfer activation by the identification of the aromatic cation radical as the initial transient (T1) formed in a photoinduced electron-transfer together with the X-pyridinyl radical.The homolytic fragmentation of the latter varies with the X-substituent in the order X = NO2 > F > AcO >CH3O, and the addition of X. to the aromatic donors leads to a series of cyclohexadienyl adducts that are identified as longer-lived transients (T2) by time-resolved (nanosecond/microsecond) spectroscopy.The phototransients T1 and T2 together account for the different types of aromatic product (resulting from ring substitution, side-chain substitution and dimerization) that are generated by steady-state CT photochemistry of the aromatic EDA complexes with X-pyridinium cations.

Oxidative Aromatic Nitration with Charge-Transfer Complexes of Arenes and Nitrosonium Salts

Brightly colored solutions are obtained immediately upon the exposure of various arenes (ArH) to nitrosonium (NO+) salts.The colors arise from the charge-transfer transitions of 1:1 complexes +> that are reversibly formed as persistent intermediates.However the yellow-red charge-transfer (CT) colors are readily bleached by dioxygen, and the corresponding nitroarenes (ArNO2) can be isolated in excellent yields from acetonitrile solutions.Such an oxidative aromatic nitration of aromatic donors proceeds via the initial autooxidation of the charge-transfer complex.The collapse of the resulting radical ion pair .+,NO2> to the ?-adduct, followed by the loss of proton, affords ArNO2.Direct evidence for electron transfer in the initial step when anthracene is treated with NO+PF6- stems for the isolation of (a) the anthracene ion radical salt .+PF6-> along with nitric oxide in dichloromethane solution and (b) the formation of 9-nitroanthracene (admixed with anthraquinone) in the more polar acetonitrile.The aromatic products (and isomer distribution) from oxidative aromatic nitration are highly reminiscent of those from electrophilic aromatic nitration.The possibility of common reactive intermediates in these two distinctive pathways for aromatic nitration is discussed.

OXIDATIVE CHLORINATION OF AROMATIC COMPOUNDS IN THE PRESENCE OF NITROGEN-CONTAINING OXIDIZING AGENTS

Mixture of the chlorides and nitrates of alkali metals in aqueous trifluoroacetic acid can be used for the selective oxidative chlorination of benzene, halogenobenzenes, toluene, and p-toluic acid with preparative yields.By variation of the water content of the solvent and the nitrate-chloride ratio it is possible to suppress the nitration side reaction.In the presence of oxygen or air alkali-metal nitrites can also be used as oxidizing agents in this process.The chlorinating agent in these systems is molecular chlorine, as confirmed by a comparative study of the reactions of two groups of potential chlorinating agents (nitrosyl chloride and nitryl chloride) under these conditions.The reactions of naphthalene and polymethylbenzenes with nitrosyl chloride in trifluoroacetic acid, leading to the products from chlorination and dehydrooligomerization of the aromatic substrates, were also studied.

Kinetics and Mechanism of Aromatic Thallation. Identification and Proof of Competiting Electrophilic and Electron-Transfer Pathways

The unusual occurrence of simultaneous electrophilic (two-electron) and electron-transfer (one-electron) pathways during the thallation of the homologous methylbenzenes ArCH3 is demonstrated by (1) the careful analysis and identification of three major types of products, (2) the complete dissection of the complex kinetics, and (3) the identification of the reactive intermediates by time-resolved UV-vis and ESR spectroscopy.Side-chain substitution S, dimerization D, and oxidative nuclear substitution O derive from the radical cation ArCH3+. produced as a common intermediate by electron transfer from the methylbenzene to thallium(III) trifluoroacetate in trifluoroacetic acid.The importance of ArCH3+., which is detected by both its electronic and ESR spectra, decreases in the following order, hexamethylbenzene > pentamethylbenzene > durene >> mesitylene, with a concomitant rise in electrophilic nuclear thallation R to account for the complete material balance.The striking color changes that accompany thallation are identified as charge-transfer transition in the series of transient 1:1 ?-complexes of the methylbenzene donors and the thallium(III) acceptor.Quantitative spectrophotometry employing the Benesi-Hildebrand analysis establishes the cationic Tl(O2CCF3)2+ formed by the dissociation of a single trifluoroacetate ligand from the parent thallium tris(trifluoroacetate) as the active electron acceptor.The complete analysis of the complex kinetics including kinetic isotope effects with accompany the nuclear thallation R of mesitylene as well the side-chain substitution S of hexamethylbenzene shows that the cationic Tl(O2CCF3)2+ also serves the dual function as the active electrophile and the active oxidant, respectively.The close competition between these apparently disparate pathways is quantitatively evaluated by the second-order rate constants which differ by less than an order of magnitude.Therefore, the thallation of arometic hydrocarbons represents one of the few systems in which such dual pathways, electrophilic and free radical, apparently occur side under the same experimental conditions of solvent, temperature, etc.Accordingly, it represents an unusual opportunity to delineate two-electron (concerted, electrophilic) from one-electron (stepwise, free radical) mechanism-especially as two whether they represent parallel or sequential events.