Quaternary ammonium polyelectrolytes. IV. Addition reaction between poly(4-vinylpyridinium chloride) and electrophilic vinyl compounds

It was found that the addition reaction between poly(4-vinylpyridinium chloride) and electrophilic vinyl compounds, such as acrylic acid, acrylamide, methylacrylate, and acrylonitrile. leads to ammonium quaternary polymers with a transformation degree that depends oil the reactivity of vinyl compounds. The structure of addition compounds was established by using ¹H-NMR IR, and UV spectral methods. NMR-determined values of transformation degree indicate that the reactivity of vinyl compounds decreases as follows:      

Transition states in the reaction of radical addition to the vinyl double bond

The transition states for the addition of^.CH₃, CH₃O^.,^.CCl₃,^.CF₃, and HOO^. radicals to the C and C atoms of ethylene, propylene, styrerie, acrylonitrile, methyl acrylate, vinyl acetate, and vinyl- and vinylidene chlorides were calculated using the MNDO method. A satisfactory correlation between the heats of reaction and activation energies was found. The calculated coefficients of proportionality, 0.4–0.5, are twice as high as those in the Polyani—Semenov equation. The calculated heat of reaction of radical addition was shown to be as «strong» an index of reactivity as the calculated activation barrier.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 680–684, April, 1993.     

Addition of an electrophilic carbene to an electron-deficient olefin. Kinetics of benzylchlorocarbene-diethyl fumarate reaction

Benzylchlorocarbene reacts as an electrophile with electronic deficient diethyl fumerate; the dependence of product ratio on [DEF] is consistent with formation of a carbene adduct.     

Quantum-chemical study of electrophilic addition reaction of iodine to ethylene

The relative stability of and barrier to interconversion of the two possible intermediates in the electrophilic addition of iodine to ethylene have been studied by means of ab initio molecular calculations with pseudopotential approximations. The geometries of the 2-iodoethyl and ethylene iodonium cations have been optimized by the energy gradient technique with pseudopotential approximations. From the results of the calculations, it is found that the only possible intermediate is the cyclic ethylene iodonium ion, as shown by experiments.     

Electrophilic aromatic addition reaction: electrophilic attack at an aromatic H substituent position

[reaction: see text] We report and propose a mechanism for an unusual electrophilic aromatic addition reaction (Ad(E)()Ar). During our preparation of 5,7-dibromo-8-methoxyquinaldine as a key intermediate in the synthesis of 7-bromoquinaldine-5,8-dione, direct bromination in either acidic or neutral conditions led only to the formation of 5-bromo-8-methoxyquinaldine. Under basic methanolic conditions, however, we unexpectedly obtained the 5,7-dibromo-8,8-dimethoxy-7,8-dihydroquinaldine adduct 2a. This result not only allows for the functionalization of aromatic compounds via the addition adducts, but also introduces the possibility of an alternate mechanism for electrophilic substitution reactions.     

Synthesis of (-)-ilimaquinone via a radical decarboxylation and quinone addition reaction

[reaction: see text] A stereoselective synthesis of (-)-ilimaquinone (4) is presented. The synthetic strategy is based on a novel radical decarboxylation and quinone addition methodology that produces quinone 7 from reaction of thiohydroxamic acid derivative 8 with benzoquinone (9). Final functionalization of 7 to ilimaquinone (4) is achieved by exploring the electronic effects of the residual thiopyridyl group.     

Addition reaction of various azoles to perfluoromethyl vinyl ether

Chemistry of Heterocyclic Compounds - The addition reaction of perfluoromethyl vinyl ether to various azoles – derivatives of pyrrole, imidazole, pyrazole, indole, benzotriazole, carbazole,...     

Comparison of the electrophilic and free-radical addition of halogens with hexafluoro-1,3-butadiene and 1,3-butadiene

Ionic and photochemical reaction of chlorine (Cl₂), bromine (Br₂) and iodine monochloride (ICl) to hexafluoro-1,3-butadiene (1) and 1,3-butadiene (2) were carried out under conditions that would provide product distributions under controlled ionic or free-radical conditions. Product distributions for ionic reaction of Cl₂ and Br₂ with 1 are similar and suggest a weakly-bridged halonium ion species. Theoretical calculations support weakly-bridged chloronium and bromonium ions for both dienes 1 and 2. There are more of the 1,4-dihalo-2-butene products from ionic halogenation of 1 than 2 which correlates with the greater charge density on carbon-4 of halonium ions from 1. Ionic and free-radical reactions of ICl with 1 give 8 and 2% of 3-chloro-4-iodohexafluoro-1-butene and 4-chloro-3-iodohexafluoro-1-butene, respectively. The minor cis-1,4-dihalo-2-butene products from 1 and 2 are reported when formed.     

Diastereoselective vinyl addition to chiral hydrazones via tandem thiyl radical addition and silicon-tethered cyclization

A diastereoselective method for addition of a vinyl group to alpha-hydroxy hydrazones under neutral tin-free radical cyclization conditions, leading to substituted vinylglycinols, is presented. Tandem thiyl radical addition/cyclization upon a silicon-tethered vinyl group followed by treatment with potassium fluoride accomplishes a one-pot neutral vinyl addition process to afford acyclic allylic anti-hydrazino alcohols in good yield.     

Steric diversion—I : Addition of halogens and pseudo-halogens to isolongifolene

Addition of halogens (Cl₂, Br₂) and pseudo-halogens (ICl, halogen azides, NOCl) to solongifolene does not yield any “normal” addition products due to severe steric hindrance to the approach of counter ion at C-7. Initially formed halogenonium ions undergo elimination or rearrangement to give “abnormal” products. The term Steric Diversion is suggested to describe this switch over from the “normal” route.     

Reactivity of diacetylplatinum(II) complexes: Oxidative addition of halogens and hydrogen halides

Diacetylplatinum(II) complexes [Pt(COMe)₂()] ( = bpy, 3a; 4,4′-t-Bu₂-bpy, 3b), obtained by the reaction of [Pt(COMe)₂X(H)()] with NaOH in CH₂Cl₂/H₂O, were found to undergo oxidative addition reactions with halogens (Br₂, I₂) yielding the platinum(IV) complexes (trans, OC-6-13)/(cis, OC-6-32) [Pt(COMe)₂X₂()] ( = bpy, X = Br, 4a/4b; I, 4c/4d;  = 4,4′-t-Bu₂-bpy, X = Br, 4e/4f; I, 4g/4h). The diastereoselectivity of the reactions proved to be strongly dependent on the solvent. The oxidative addition of (SCN)₂ resulted in the formation of (OC-6-13)-[Pt(COMe)₂(SCN)₂()] ( = bpy, 4i; 4,4′-t-Bu₂-bpy, 4j). In a reaction the reverse of their formation, the diacetylplatinum(II) complexes 3 underwent oxidative addition with anhydrous HX (X = Cl, Br, I), prepared in situ from Me₃SiX/H₂O, yielding diacetyl(hydrido)platinum(IV) complexes [Pt(COMe)₂X(H)()] ( = bpy, X = Cl, 5a; Br, 5b; I, 5c;  = 4,4′-t-Bu₂-bpy, X = Cl, 5d; Br, 5e; I, 5f). Furthermore, diacetyldihaloplatinum complexes 4 were found to undergo reductive elimination reactions in boiling methanol yielding acetylplatinum(II) complexes [Pt(COMe)X()] ( = bpy, X = Br, 6b; I, 6c;  = 4,4′-t-Bu₂-bpy, X = Br, 6e; I, 6f). All complexes were characterized by microanalysis, IR and ¹H and ¹³C NMR spectroscopy. Additionally, the bis(thiocyanato) complex 4j was characterized by single-crystal X-ray diffraction analysis.     

Addition of Bis(trimethylsiloxy)phosphine to Diphenyl(vinyl)- and Phenyldivinylphosphines

Russian Journal of General Chemistry -     

Nucleophilic, radical, and electrophilic (phenylsulfonyl)difluoromethylations

Selective incorporation of a fluoroalkyl moiety to modulate the properties of an organic molecule has become a frequently used strategy in life science- and materials science-related applications. In this context, selective introduction of a (phenylsulfonyl)difluoromethyl group (PhSO₂CF₂) into organic molecules has attracted much attention, since the PhSO₂CF₂ group can be regarded as a “chemical chameleon” that can be readily transformed into difluoromethyl (CF₂H), difluoromethylene (–CF₂–), and difluoromethylidene (CF₂) functionalities. This article overviews the recent development of (phenylsulfonyl)difluoromethylation reactions from 2003, including the nucleophilic (phenylsulfonyl)difluoromethylations with PhSO₂CF₂H, PhSO₂CF₂SiMe₃ and PhSO₂CF₂Br reagents, free radical (phenylsulfonyl)difluoromethylations with PhSO₂CF₂I reagent, and electrophilic (phenylsulfonyl)difluoromethylations with a hypervalent iodine(III)-CF₂SO₂Ph reagent.     

Addition of atomic hydrogen to acetylene. Chain reactions of the vinyl radical

The main reaction products resulting from the addition of atomic hydrogen to acetylene are shown to be ethylene, 1,3-butadiene, and benzene. The mechanism involves chain reactions of the vinyl and butadienyl radicals, which regenerate atomic hydrogen. Some of the rate parameters are estimated.     

Radical addition to isonitriles: a route to polyfunctionalized alkenes through a novel three-component radical cascade reaction

The reaction of aromatic disulfides, alkynes, and isonitriles under photolytic conditions affords polyfunctionalized alkenes--beta-arylthio-substituted acrylamides or acrylonitriles--in fair yields through a novel three-component radical cascade reaction. The procedure entails addition of a sulfanyl radical to the alkyne followed by attack of the resulting vinyl radical to the isonitrile. A fast reaction, e.g., scavenging by a nitro derivative or beta-fragmentation, is necessary in order to trap the final imidoyl radical, since addition of vinyl radicals to isonitriles seems to be a reversible process. The stereochemistry of the reaction is discussed, particularly with respect to the stereochemical outcome of related hydrogen abstraction reactions by the same vinyl radicals. The lower or even inverted preference for either geometrical isomer observed in our cases with respect to that encountered in hydrogen abstraction reactions is explained in terms of transition-state interactions and/or isomerization of the final imidoyl radical. The latter possibility is supported by semiempirical calculations, which show that the spin distribution in the imidoyl radical can allow rotation of the adjacent carbon-carbon double bond prior to beta-fragmentation.     

多氯甲烷与双环[2,2,1]-2,5-庚二烯光敏化离子自由基加成反应

以芳胺为光敏剂, 研究了多氯甲烷与双环[2,2,1]-2,5-庚二烯离子自由基加成反应, 在所研究的体系中只得到3,5-加成物, 说明该反应具有高度的区域选择性. 结合多氯甲烷对光敏剂N, N, N', N'-四甲基联苯二胺光物理性质的影响, 提出了反应经过离子自由基复俣物中间体的反应机理.     

Oxidative addition of iodo-acetonitrile and of elemental halogens to [Pt3(mu-CO)3(PCy3)3

The reaction of [Pt3(mu-CO)3(PCy3)3](1) with one mole-equivalent of iodo-acetonitrile was quantitative at -70 degrees C giving the oxidative addition product [Pt3(mu-CO)3(PCy3)3(I)(CH2CN)](2). Fragmentation of was observed in solution giving [Pt2I(CH2CN)(CO)2(PCy3)2](3) which is the major product at room temperature if the starting cluster/reactant ratio is equal to or less than 1 to 1.5. Dimer 3 decomposes slowly in solution giving [Pt2I2(CO)2(PCy3)2](4a) and succinonitrile. Monomer [PtI(CH2CN)(CO)(PCy3)] was the final product of the reaction when using excess of iodo-acetonitrile. The reactions of with one mole-equivalent of halogens X2 gave the new 44-electron clusters [Pt3X(micro-CO)2(micro-X)(PCy3)3](X = I2(7a) or Br2(7b)) by oxidative addition followed by substitution of CO by X-. Fragmentation of and took place in solution when using one and a half mole-equivalents of X2 giving dimers 4a and [Pt2Br2(CO)2(PCy3)2](4b) as well as [Pt2X2(mu-X)2(CO)2(PCy3)2]. Monomers cis-[PtX2(CO)(PCy3)] were the final products of the reaction of with excess of halogens. Insertion of SnCl2 was observed into the Pt-Pt bond but not into the Pt-X bond, when equimolar amounts of SnCl2 x 2H2O were added to a solution of 4a or its chloro-analogue giving [Pt2X2(micro-SnCl2)(CO)2(PCy3)2]. The Pt(I) dimers have unusually small J(Pt-Pt) values as observed by 195Pt NMR and calculated by DFT. These values showed periodic changes comparing 4a and its analogues with other halides and mixed halide dimers.