Reaction of N1, N2-diarylamidines with chloranil and 2,3-dichloro-1,4-naphthoquinone

Nucleophilic attack by N² of N¹ N²-diarylformamides 1a-c on C-2 of chloranil (2) and subsequently by N¹ on C-1 of 2 initiates the formation of benzimidazolinones 8a-c. In contrast, when 1b-e is reacted with 2,3-dichloro-1,4-naphthoquinone (9) , both chlorine atoms are successively substituted by the two nitrogen atoms and 2-(arylamino)-3-(N-formylarylamino)-1,4-naphthoquinones 13b-e result, which (probably via their cyclic tautomers 12b-e ) may be cyclodehydrogenated to form N¹,N³-diarylnaphtho[2,3-d] imidazoline-2,4,9-triones (as 14b,c ). On the other hand, N¹,N²diarylacetamidines 15a-d attack 2 and 9 at C-2 with N² but subsequently exert nucleophilic character at the acetamidine α-carbon attacking C-1 of 2 and 9 , respectively, thus forming 1-aryl-2-(arylimino)-3a-hydroxy-2,3,3a,6-tetrahydro-1N-indol-6-ones 18a-d and 3-aryl-2-(arylimino)-9b-hydroxy-2,3,5,9b-tetrahydro-1-H-benz[e]indol-5-ones 19b,c , respectively. The latter may be thermally dehydrated to the fully conjugated 2,5-dihydro-3H-benz[e]indol-5-ones 20b,c. Unambiguous structural assignments for 18b and 20c are made on the basis of X-ray crystal structure analyses.     

Interaction of 2,3-dichloro-1,4-naphthoquinone with n-butylamine in halocarbon solvents

The rapid interaction between 2,3-dichloro-1,4-naphthoquinone (DClNQ) and n-butylamine results in the formation of 2N(n-butylamino)-3-chloro-1,4-naphthoquinone as the final product. The reaction is found to proceed through the initial formation of charge-transfer (CT) complex as an intermediate. The final product of the reaction has been isolated and characterized using FTIR, H1 and C13 NMR spectroscopy, mass spectrometry, and elemental analysis. The rate of formation of product has been measured as a function of time in different halocarbon solvents, viz., chloroform, dichloromethane and 1:1 (v/v) mixture of two solvents. The pseudo first order and second order rate constants at various temperatures for the transformation process were evaluated from the absorbance time data. The activation parameters (E(a), DeltaS#, DeltaH#, and DeltaG#) were obtained from temperature dependence of rate constants. The influence of dielectric constant on the properties of reaction was discussed and the probable course of reaction is presented.     

On the reliability of equilibrium data of the charge-transfer complex between 2,3-dichloro-1,4-naphthoquinone and hexamethylbenzene

In view ofHammond's warning⁶ about the Conspiracy of errors, found in the case of low values of equilibrium constants of charge-transfer complexes a case is made out for redetermining the values for the system hexamethylbenzene—2,3-dichloro-1,4-naphthoquinone. Uncertainties in the parameters were estimated using theLiptay ⁸ matrix procedure. The solvent used was dichloromethane. The following data were obtained at 25°C: vC T = 22,220 cm^–1;E _A=0.99 eV;K =2599±57 l²·cm^–1·mol^–2. _max= 1020 ± 148 cm^–1··1;K=2.55±0.37 l·mol^–1; –H=2.7±0.3 kcal·mol^–1.With 1 Figure     

Solvent effect as the result of frontier molecular orbital interaction-1 : The diels-alder reaction between 1,4-naphthoquinone and 2,3-dimethylbutadiene

A kinetic investigation of the solvent effect in the Diels-Alder reaction of2,3-dimethylbutadiene and 1,4-naphthoquinone was undertaken and a hyperbolic correlation was obtained with the Acceptor Numbers (AN) of the solvent. Since ANs correlate with the LUMO of the solvent, the results can be rationalized in terms of an interaction between the LUMO of the solvent and the HOMO of the quinone which determines the MO energy of the solvated quinone. This rationalization seems useful when reactants, products and transition state are weakly polar.     

Reaction of 2,3-dichloro-1,4-naphthoquinone with dithiooxamide. Synthesis of dibenzo[b,i]thianthrene-5,7,12,14-tetrone

The reaction of 2,3-dihalogeno-1,4-naphthoquinone with dithiooxamide gave dibenzo[b,i]thianthrene-5,7,12,14-tetrone in high yield but not 2,2′-bis(naphtho[2,3-d]thiazole-4,9-dione) which was previously reported. A similar reaction of 3,4-dichloro-N-phenylmaleimide with dithiooxamide also gave the corresponding sulfur heterocycles but not the reported bisthiazole.     

Reactions of Substituted Indoles with 2,3-Dichloro-1,4-naphthoquinone and Electrochemical Properties of Some 2,3-Substituted 1,4-Naphthoquinones

Russian Journal of Organic Chemistry - The reactions of 2,3-dichloro-1,4-naphthoquinone with some indoles and thiols were investigated. The resulting nucleophilic substitution products were...     

Charge transfer interaction of 4-acetamidophenol (paracetamol) with 2,3-dichloro-1,4-naphthoquinone: a study in aqueous ethanol medium by UV-vis spectroscopic and DFT methods

4-Acetamidophenol (paracetamol) is shown to form charge transfer complex with 2,3-dichloro1,4-naphthoquinone in aqueous ethanol media exhibiting the unusual 2:1 (paracetamol:quinone) stoichiometry. The complexation enthalpy and entropy have been estimated from the formation constant (K) determined spectrophotometrically at five different temperatures. In aqueous ethanol mixtures of varying composition K increases with increasing dielectric constant of the medium. This has been rationalized by calculating the electronic charge distribution in paracetamol molecule and its conjugate base at the DFT/B3LYP/6-31++G(d,p) level. The theoretically calculated vertical ionization potential of paracetamol also agrees with reported experimental value.     

氨甲苯酸的荷移分光光度法测定

研究了氨甲苯酸与2,3 二氯 5,6 二氰 1,4 对苯醌的荷移反应。结果表明:在水介质中,两者于30℃水浴中恒温130min,可形成稳定的络合物,其λmax=340nm,线性范围1～9μg mL,相关系数r=0.9990,表观摩尔吸光系数ε=1.1×104L·mol-1·cm-1,方法的回收率99.93%～100.1%,相对标准偏差为0.72%～1.1%。用该方法测定了氨甲苯酸注射液,结果与文献方法一致。     

A novel three-component one-pot reaction involving alkynes, urea or thiourea, and aldehydes

A novel three-component, one-pot condensation yielding 2-amino-4H-1,3-oxazines or 2-amino-4H-1,3-thiazines from alkynes, urea or thiourea, and aldehydes is described. [reaction: see text]     

Synthesis of 2-alkoxy 1,4-naphthoquinone derivatives as antiplatelet,antiinflammatory, and antiallergic agents

In our continuing search for novel antiplatelet, antiallergic, and antiinflammatory agents, 2-alkoxy derivatives of 1,4-naphthoquinone were prepared. Some of these compounds showed significant antiplatelet, antiallergic, and antiinflammatory activities. Among them, 2-propoxy-1,4-naphthoquinone and 2-butoxy-1,4-naphthoquinone exhibited potent inhibitory effect on neutrophil superoxide anion formation. These two compounds are worthy of further exploration.     

Synthesis,mechanism, and property aspects of a new class of polyethers: Poly(1,4-dichloro-2,3-epoxybutane)s

Ring-opening polymerization and copolymerization of the cis and trans isomers of 1,4-dichloro-2,3-epoxybutane has let to an interesting 50% Cl. This family of polymers is expected to acquire commercial importance.     

Multiple and sequential charge transfer interactions occurring in situ: A redox reaction of thiazolidine-2-thione with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone

Interaction of thiazolidine-2-thione (T2T) as an electron donor with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) as an electron π-acceptor has been studied. Electronic absorption spectra of the system T2T-DDQ in several organic solvents of different polarities have been measured. A charge transfer (CT) complexation has occurred between T2T and DDQ. This CT interaction has led to a redox reaction in which T2T has been oxidized to the corresponding dehydrogenated T2T (T2T-2H), meanwhile DDQ has been fully reduced to the corresponding hydroquinone (DDQH2). However, the two new species, resulting in situ, have been interacted, whereas a CT complex having the formula (T2T-2H·DDQH2) has occurred. IR, 1H NMR and mass spectra were used for ascertaining the structural formula of the synthesized CT complex. Formation constants (KCT), molar absorption coefficients (?CT) and thermodynamic properties of this CT interaction in various organic solvents were determined and discussed. The obtained KCT and ?CT values have indicated that T2T-2H is a weak CT donor, whereas the formed CT complex has a low stability and it is classified as a contact-type CT complex.     

Suggestion of an organometallic intermediate in an intramolecular dechlorination reaction involving copper(I) and a ArCH2Cl moiety

A copper(I)-mediated reductive dechlorination reaction involving an "internal" chloromethylene substrate at the pyridyl 6-position of one TMPA arm (TMPA triple bond TPA triple bond tris(2-pyridylmethyl)amine) leads to a 1:1 ratio of the starting ligand 6ClCH2-TMPA and a new methyl-TMPA product, 6CH2H-TMPA. On the basis of observed product distributions and a kinetic study, a reaction mechanism involving intramolecular oxidative insertion of Cu(I) to the C-Cl substrate is suggested. The resulting organometallic intermediate is then protonated, leading to the observed products.