Halogenation of N-substituted p-quinone monoimines and p-quinone monooxime esters: X. Halogenation of N-aroyl-2,5(2,3)-dialkyl-1,4-benzoquinone monoimines and their reduction products

Introduction of a strong electron-withdrawing substituent to the nitrogen atom of 2,5(2,3)-dialkyl-1,4-benzoquinone imines makes their halogenation products, the corresponding cyclohexene derivatives, very unstable and favors halogenation of methyl groups in the quinoid ring. Bromination of 4-amino-N-aroyl-2,5-dialkyl-6-bromophenols gave 2,5-dialkyl-6-benzoyloxy-3,5-dibromocyclohex-2-ene-1,4-diones.     

Halogenation of N-substituted para-quinone monoimines and para-quinone monoximes ethers: IX. Halogenation of N-aroyl-2,6(3,5)-dimethyl-1,4-benzoquinone monoimines and their reduced forms

At the halogenation of N-aroyl-2,6(3,5)-dimethyl-1,4-benzoquinone imines we found the halogenation of methyl groups to occur. The bromination of N-aroyl-2,6-dimethyl-1,4-benzoquinone imines yielded 3,6-dibromo-2,6-dimethyl-5-aroyloxycyclohex-2-ene-1,4-diones due to the strong acceptor property of the ArCO group and high redox potentials of N-aroyl derivatives. In the chlorination of N-aroyl-3,5-dimethyl-1,4-benzoquinone imines the chlorine addition to the C=C bond of the quinoid ring proceeded both by the trans- and syn-scheme.     

Halogenation of n-substituted p -quinone monoimines and p -quinone monooxime esters: VIII. Halogenation of N -aroyl(arylsulfonyl)-2,6-di- tert -butyl-1,4-benzoquinone monoimines and their reduced forms

Chlorination of N-aroyl(arylsulfonyl)-2,6-di-tert-butyl-1,4-benzoquinone imines gave Z and E isomers of 4-arylsulfonylimino-2,6-di-tert-butyl-5,6-dichlorocyclohex-2-en-1-ones and Z isomers of 4-aroyl-(arylsulfonyl)imino-2,6-di-tert-butyl-5,5,6-trichlorocyclohex-2-en-1-ones, in which the tert-butyl group on the sp ³-hybridized carbon atom occupies exclusively the axial position. The formation of Z/E-isomeric structures is related to configurational stability of the chlorination products. The chlorination of 4-aroylamino-2,6-di-tertbutylphenols was found to be accompanied by replacement of one tert-butyl group by chlorine atom with formation of 4-aroylimino-6-tert-butyl-2,3,5,6-tetrachlorocyclohex-2-en-1-ones. Original Russian Text ? A.P. Avdeenko, V.V. Pirozhenko, O.V. Shishkin, G.V. Palamarchuk, R.I. Zubatyuk, S.A. Konovalova, O.N. Ludchenko, 2008, published in Zhurnal Organicheskoi Khimii, 2008, Vol. 44, No. 6, pp. 818–824. For communication VII, see [1].     

Hydrohalogenation of N-acetyl(aroyl)-1,4-benzoquinone monoimines

New N-acetyl-1,4-benzoquinone monoimines alkyl-substituted in the quinoid ring were synthesized. The hydrohalogenation of N-acetyl(aroyl)-1,4-benzoquinone monoimines proceeds exclusively in keeping with the 1,4-addition. The hydrochlorination occurs along the ionic mechanism, in the hydrobromination grows the role of the radical mechanism.     

Halogenation of N-substituted p-quinone monoimines and p-quinone monooxime ethers: XIV. Halogenation of N-[arylsulfonylimino(phenyl)methyl]-2,5-dialkyl-1,4-benzoquinone monoimines and their reduction products

Despite steric hindrances created by the bulky substituent on the nitrogen atom, halogenation of 2,5-dialkyl-N-[arylsulfonylimino(phenyl)methyl]-1,4-benzoquinone monoimines fairly readily gives their derivatives having two halogen atoms in the quinoid ring.     

Halogenation of N-substituted para-quinone monoimine and para-quinone monooxime esters: V. Chlorination and bromination of N-arylsulfonyl-1,4-benzoquinone monoimines dialkyl-substituted in the quinoid ring

The direction of halogen addition to N-arylsulfonyl-1,4-benzoquinone monoimines dialkyl-substituted in the quinoid ring is governed by the steric factors: the size and position of the substituent, the halogen volume, and the position of the substituent at the nitrogen. The first stage of halogenation of N-arylsulfonyl-4-aminophenols with two alkyl substituents in the phenylsulfonyl ring largely occurs as electrophilic substitution.     

Halogenation of N-substituted para-quinone monoimine and para-quinone monooxime esters: VI. Regular trends in chlorination and bromination of N-arylsulfonyl-1,4-benzoquinone monoimines alkyl-substituted in the quinoid ring

Reactions of halogens with N-arylsulfonyl-1,4-benzoquinone monoimines occur with the formation of a halogenonium ion that either transforms into a carbocation where the first halogen atom adds to the carbon in the ortho-position relative to the carbonyl carbon, or the halogenonium ion adds directly the second halogen atom.     

Halogenation of N-substituted p-quinone imines and p-quinone oxime esters: IV. Chlorination and bromination of N-arylsulfonyl-2(3)-methyl(2-chloro)-1,4-benzoquinone monoimines

The addition of halogens to N-arylsulfonyl-1,4-benzoquinone imines, which exist in a solution as Z and E isomers, is controlled by the steric factor. Z-E Isomerization strongly affects the stability of cyclohexene structures formed by halogenation of 1,4-benzoquinone imines. The halogenation of N-arylsulfonyl-1,4-benzoquinone imines was found to be accompanied by prototropic rearrangement.     

Synthesis and structure of N-aryl(phenoxy, benzylidene)acetyl-1,4-benzoquinone monoimines

New N-aryl(phenoxy, benzylidene)acetyl-1,4-benzoquinone monoimines were synthesized by reaction of aminophenols with arylacetyl, phenoxyacetyl, and cinnamoyl chlorides in dimethylformamide-acetic acid (1: 3) in the presence of anhydrous sodium acetate. Structural parameters of the products and their probable biological activity were determined.     

Reaction of N-acyl-and N-[N-arylsulfonylbenz(acet)imidoyl]-1,4-benzoquinone monoimines with hydrazoic acid

N-Aroyl-3,5-dimethyl-and N-[N-arylsulfonylbenz(acet)imidoyl]-3,5-dimethyl-1,4-benzoquinone monoimines react with hydrazoic acid according to the 1,4-addition pattern. N-Acyl-2,3,5,6-tetrachloro-1,4-benzoquinone monoimines take up hydrazoic acid at the double C=N bond (1,2-addition).     

Halogenation of N-substituted p-quinone monoimines and p-quinone monooxime esrers: XI. Synthesis and halogenation of 4-[aryl(alkyl)aminocarbonyl-oxyimino]cyclohexa-2,5-dien-1-ones

4-[Aryl(alkyl)aminocarbonyloxyimino]cyclohexa-2,5-dien-1-ones were synthesized by treatment of various substituted p-quinone monooximes with aryl isocyanates. The selectivity in the halogenation of the obtained p-quinone monooxime esters depended on the substrate structure and was either completely (syn addition) or partly regioselective (syn or anti addition). In all cases, the effect of steric factor was crucial, and the reaction was accompanied by halogenation of the aryl fragment.     

Activated sterically strained C=N bond in N-substituted p-quinone mono- and diimines: XIII. Reactions of N-alkyl(aryl, trifluoromethyl)sulfonyl-, N-arylsulfinyl- and N-arylsulfanyl-1,4-benzoquinone monoimines with alcohols

Steric strains arising between the substituent atoms at nitrogen (S, SO, or SO₂) and the methyl group located in positions 3 or 5 of the quinoid ring of 3,5-dimethyl-substituted quinone monoimines lead to the increased angle C=N-S. As a result in these quinone monoimines the reactions of 1,2-addition become thermodynamically possible since the formation of quinolide structures with the sp³-hybridized carbon atom removes the steric strain.     

Halogenation of N-substituted <Emphasis Type="Italic">p</Emphasis>-quinone monoimines and <Emphasis Type="Italic">p</Emphasis>-quinonemonooxime ethers: XII. Halogenation of <Emphasis Type="Italic">N</Emphasis>-aroyl-2(3)-methyl-1,4-benzoquinone monoimines and their reduced forms

A strong acceptor substituent at the nitrogen atom of the N-substituted p-quinone monoimine decreases the stability of the halogen-containing cyclohexene structures formed at the addition of a halogen molecule to the C=C bond of the quinoid ring. As a result of the bromination of N-benzoyl-2-methyl-1,4-benzoquinone monoimine alongside the usual products of addition and substitution the 5-benzoyloxy-2,3,6-tribromo-6-methylcyclohex-2-ene-1,4-dione was isolated.     

Solvatochromic studies of interactions between surfactants and poly(N-substituted acrylamide)s

Interactions between poly(N-substituted acrylamide)s and surfactants, such as sodium dodecyl sulfate (SDoS) and sodium decyl sulfate (SDeS), in aqueous solutions were investigated using a solvatochromic probe. The polymers used were poly(N,N-dimethylacrylamide) (PDMA), poly(N-isopropylacrylamide) (PIPA), poly(N-acryloylpyrrolidine) (PAPR), and poly(vinylpyrrolidone) (PVPy) for comparison. They were labeled with pyridinium dicyanomethylide chromophore as a solvatochromic probe, and the changes in the microenvironment polarity of the polymer upon association with surfactant micelles were investigated by monitoring the λ_max in the absorption spectra of the probe molecule. It was found that the Gibbs free energy of micelle stabilization by polymer complexation for SDoS is 7.6, 4.1, and 2.2 kJ mol⁻¹, and for SDeS 5.1, 2.9, and 0.8 kJ mol⁻¹ with PIPA, PAPR, and PDMA, respectively. These results indicate that the complexation between polymer and surfactant is influenced not only by the alkyl-chain length of the surfactant, but also by the polymer side groups.     

N-substituted salicylaldimine complexes of rhodium(III) and related rhodium(III) organometallic derivatives

A series of new Rh^III complexes with N-substituted salicylaldimines have been prepared of the form [RhSBPy₂]PF₆ where SB is a tetradentate N,N′-substituted bis(salicylaldimine) or represents two molecules of a corresponding bidentate derivative. Several of these complexes have been reduced with 0.5% sodium amalgam and the products reacted with CH₃I to yield the organometallic derivatives CH₃RhSBPy.     

Halogenation of <Emphasis Type="Italic">N</Emphasis>-substituted <Emphasis Type="Italic">p</Emphasis>-quinone monoimines and <Emphasis Type="Italic">p</Emphasis>-quinone monooxime ethers: XV. Synthesis and bromination of 4-(cinnamoyloxyimino)-cyclohexa-2,5-dienones

New 4-(cinnamoyloxyimino)cyclohexa-2,5-dien-1-ones were synthesized, and their bromination afforded bromine addition products to the syn- and anti-C=C bonds of the quinoid ring. In all cases, bromine addition to the C=C double bond of the cinnamoyl fragment was observed.     

Synthesis and polymerization of 7,7-bis(alkoxycarbonyl)-1,4-benzoquinone methides

7,7-Bis(methoxycarbonyl)-, 7,7-bis(ethoxycarbonyl)-, and 7,7-bis(isopropoxycarbonyl)-1,4-benzoquinone methides ( 4a, 4b , and 4c ) were successfully prepared as pure, isolable yellow-orange needles. The values of the first reduction potential for 4a, 4b , and 4c were measured in dichloromethane containing tetrabutylammonium perchlorate by cyclic voltammetry to be −0.54, −0.55, and −0.55 V, respectively, indicating that the alkyl groups do not significantly affect their electron-accepting properties. An anionic initiator butyllithium induced the homopolymerizations of 4a–c at 0°C, but a cationic initiator boron trifluoride etherate did not of 4a–c at 0°C. Compounds 4a and 4b homopolymerized with a radical initiator 2,2′-azobis(isobutyronitrile) (AIBN), but 4c did not, probably due to a larger steric hindrance effect of the isopropyl group compared with methyl and ethyl groups. Homopolymerizable compound 4a copolymerized with styrene in benzene in the presence of AIBN in a random fashion to give the monomer reactivity ratios r₁ ( 4a ) = 2.40 ± 0.40 and r₂ (styrene) = 0.01 ± 0.02 at 60°C and the Q and e values of 4a were 21.2 and +1.13, respectively, indicating that 4a is a highly conjugative and electron-accepting monomer, while the nonhomopolymerizable compound 4c copolymerized with styrene in a perfectly alternating fashion in benzene in the presence of AIBN at 60°C. No copolymerizations of 4a or 4c with 7,7,8,8-tetracyanoquinodimethane took place in dichloromethane in the presence of AIBN at 60°C. © 1996 John Wiley & Sons, Inc.     

Bismuth(III) complexing with some N- and N,N-substituted thioureas

Stability constants at ionic strength I = 2 and 293 K were determined spectrophotometrically for multiligand bismuth(III) complexes with thiourea (Tu), N-phenylthiourea (Ptu), N-phenyl-N′-propylthiourea (Pptu), N,N′-diphenylthiourea (Bptu), and N-allyl-N′-propylthiourea (Aptu). The protonation constants of these ligands in perchloric acid solutions were also determined. The stability of the listed complexes changes in the following order of ligands: aptu > tu > pptu > ptu > bptu. This order coincides with the order of changing protonation constants. Original Russian Text ? N.N. Golovnev, G.V. Novikova, and A.A. Leshok, 2009, published in Zhurnal Neorganicheskoi Khimii, 2009, Vol. 54, No. 2, pp. 374–376.     

Chlorination of N-(N-Arylsulfonylarylimidoyl)-1,4-benzoquinone Imines and Their Reduced Forms

The study of chlorination of N-(N-arylsulfonylarylimidoyl)-1,4-benzoquinone imines and of N-(N-arylsulfonylarylimidoyl)-1,4-aminophenols revealed that the dominant stage in the process was the formation of cyclohexene structures, 4-(N-arylsulfonylarylimidoyl)imino-2,5,6-trichloro-2-cyclohexene-1- ones, resulting from addition of a Cl₂ molecule across the C = C bond of the quinoid ring. These substances suffer a prototropic rearrangements yielding N-(N-arylsulfonylarylimidoyl)-2,3,6-trichloro-4-aminophenols. The latter are the most common reaction products. The products of deeper chlorination were also obtained.     

Synthesis and thiocyanation of <Emphasis Type="Italic">N</Emphasis>-alkyl(trifluoromethyl)sulfonyl 1,4-benzoquinone monoimines

New N-alkyl(trifluoromethyl)sulfonyl 1,4-benzoquinone monoimines were synthesized, and their thiocyanation gave 5-alkyl(trifluoromethyl)sulfonylamino-1,3-benzoxathiol-2-ones. An intermediate thiocyanation product, 5-trifluoromethylsulfonylamino-1,3-benzoxathiol-2-imine, was isolated for the first time.