18936-17-9Relevant academic research and scientific papers
Cyanidation of halogen compounds and esters catalyzed by PEG400 without solvent
Cao,Chen,Pei
, p. 2203 - 2207 (2007/10/03)
Primary aliphatic and aromatic nitriles were synthesized in excellent yields (84-96%) and purity by the cyanidation of halogen compounds and esters with dry powdered sodium cyanide catalysed by phase transfer catalyst PEG400 under solvent-free conditions.
The MTO-catalyzed oxidative conversion of N,N-dimethylhydrazones to nitriles
Stankovic, Sasa,Espenson, James H.
, p. 1579 - 1580 (2007/10/03)
Methyltrioxorhenium catalyzes the fast and efficient oxidation of aldehyde N,N-dimethylhydrazones to the corresponding nitriles in high yield.
Substituent Effects on the C-C Bond Strength, 15. Geminal Substituent Effects, 7. Thermochemistry and Thermal Decomposition of Alkyl-substituted Tricyanomethyl Compounds
Rakus, Klaus,Verevkin, Sergej P.,Beckhaus, Hans-Dieter,Ruechardt, Christoph
, p. 2225 - 2234 (2007/10/02)
The thermolysis reactions of the tricyanomethyl compounds 10a-c were studied in solution. 2,2-Dicyano-3-methyl-3-phenylbutyronitrile (10a) and 2,2-dicyano-3-methyl-3-(4-nitrophenyl)butyronitrile (10b) decomposed heterolytically into carbenium ions and (CN)3C(-) anions, while 9-methyl-9-(tricyanomethyl)fluorene (10c) underwent about 11percent homolytic C-C bond cleavage into 9-methyl-9-fluorenyl- and tricyanomethyl radicals.The rates of the homolysis were determined by a radical scavenger procedure under conditions of pseudozero order kinetics.From the temperature effect on the rate constants the activation parameters were determined -1, ΔS(excit.) (10c) = 58 +/- 5 J mol-1 K-1>.Standard enthalpies of formation ΔHf0 (g) were determined for 2,2-dicyanopropionitrile (2) (422.45 kJ mol-1), 2,2-dicyanohexanenitrile (3) (349.74 kJ mol-1), 2,2-dicyano-3-phenylpropionitrile (4) (540.75 kJ mol-1), 2-butyl-2-methylhexanenitrile (5) (-133.20 kJ mol-1), 2,2-dimethylpentanenitrile (6) (-45.78 kJ mol-1), and 2-methylbutyronitrile (7) (2.44 kJ mol-1) from the enthalpies of combustion and enthalpies of sublimation/vaporization.From these data and known ΔHf0 (g) values for alkanenitriles and -dinitriles, thermochemical increments for ΔHf0 (g) were derived for alkyl groups with one, two, or three cyano groups attached.The comparison of these increments with those of alkanes reveals a strong geminal destabilization, which is interpreted by dipolar repulsions between the cyano groups. - From ΔHf0 (g) of 10c and ΔH(excit.) of its homolytic decomposition the radical stabilization enthalpy for the tricyanomethyl radical 1 RSE (1) = -18 kJ mol-1 was determined.Thus, 1 is destabilized, in comparison with the RSEs of tertiary α-cyanoalkyl (23 kJ mol-1) and α,α-dicyanoalkyl (27 kJ mol-1) radicals, which were recalculated from bond homolysis measurements and the new thermochemical data.This change of RSE on increasing the number of α-cyano groups is discussed as the result of the additive contributions by resonance stabilization and increasing destabilization by dipolar repulsion.The amount of the dipolar energies was estimated by molecular mechanics (MM2). - Key Words: Enthalpies of formation / Geminal substituents, energetic interaction of / Bond cleavage, C-C, kinetics of / Radicals, stability of / Increments, thermochemical, of cyanides / Bond strength, substituent effects on
Nucleophilic Substitution Reactions of Alkyl Halides By Using New Polymer-Supported Reagents Containing Hemin
Saito, Kiyoshi,Harada, Kaoru
, p. 2562 - 2566 (2007/10/02)
A new polymer reagent consisting of hemin, divinylbenzene, and 2-methyl-5-vinylpyridine was synthesized by suspension copolymerization.Substitution reactions of primary, secondary, and tertiary alkyl halides with the hemin copolymer combined with cyanide, azide, and thiocyanate ions were given satisfactory yields.This reaction mechanism was revealed to be a SNi type on the basis of stereochemical study.The hemin copolymer was not only a polymer-supported reagent with functional capabilities, but also served to separate the product from the reaction mixture.
Substituent Effects on the C-C-Bond Strength, 2. The Thermal Stability of Tetrasubstituted Succinonitriles
Barbe, Werner,Beckhaus, Hans-Dieter,Ruechardt, Christoph
, p. 1042 - 1057 (2007/10/02)
Rate constants and activation parameters for the thermolysis reaction of ten, partly cyclic tetraalkylsuccinonitriles and of meso-2,3-dimethyl-2,3-diphenylsuccinonitrile were determined.Relationships between ΔG* (300 deg C), ΔH* and ΔS* of the thermolysis reaction on the one hand and the change in strain enthalpy during bond dissociation on the other are pointed out.A force field procedure for the estimation of the strain in α-cyanoalkyl radicals is presented.A quantitative separation of the steric and resonance effects responsible for the thermal dissociation pro cess was achieved successfully.A resonance energy of 5.3 kcal*mol-1 was deduced for tertiary α-cyanoalkyl radicals in agreement with the most recent literature data.
Free Radical Substitution. Part 38. The Effect of Solvent on the Atomic Chlorination and Bromination of 2-Substituted Butanes and the Importance of Steric Effects
Atto, Saeed Y.,Tedder, John M.,Walton, John C.
, p. 629 - 634 (2007/10/02)
The relative selectivity of atomic halogenation of 2-substituted butanes is influenced by the phase and by solvents.There are solvents which increase the selectivity compared with the gas phase and solvents which decrease the relative selectivity.However the most striking feature of the halogenation (especially the bromination) of 2-substituted butanes is the high reactivity of the 2-position notwithstanding very unfavourable polar effects.This reactivity is attributed to the release of steric compression associated with the abstraction of the tertiary hydrogen atom.The halogenation of butan-2-ol esters is associated with some decomposition of 2-butyl radical (OCOR)CH3> and the chlorination of 2-phenylbutane with the formation of olefins 2-phenylbut -1-ene and 2-phenylbut-2-ene.
Stereoselective Cyanation of Vinyl Halides Catalyzed by Tetracyanocobaltate(I)
Funabiki, Takuzo,Hosomi, Hiroaki,Yoshida, Satohiro,Tarama, Kimio
, p. 1560 - 1568 (2007/10/02)
Tetracyanocobaltate(I), 3-, which is formed in an aqueous alkaline solution under a hydrogen atmosphere, catalyzes the cyanation of vinyl halides to form 2-alkenenitriles.The reaction is stereoselective, forming nitriles with retention of configuration, except for (Z)-2-bromobut-2-ene, which forms a mixture of nearly equimolar isomeric nitriles.Reactivity is dependent on the CN:Co ratio and is highest when the ratio is slightly lower than 5:1.Presence of excess cyanide ion inhibits the reaction, but a dropwise addition of the KCN solution to maintain CN:Co3-, were detected as intermediates by 1H and 13C NMR spectroscopy, indicating that the reaction proceeds stepwise.In the first step, the ? complex is formed by the oxidative addition of a vinyl halide to 3- via a radical nonchain process; in this step stereoselectivity is determined.In the second step, which is rate determining, a 2-alkenenitrile is formed by the reductive coupling of the vinyl and cyano ligands, regenerating 3-.Clear NMR evidence has been obtained for the formation of 3-, where the olefin is (E)- or (Z)-cinnamonitrile.A high degree of electron transfer from 3- to olefin was indicated by the large upfield shifts of the olefinic carbon atom resonances by coordination.
The Question of Tautomerism of Alkylnitrile and Isonitrile Cations
Chess, Edward K.,Lapp, R. L.,Gross, Michael L.
, p. 475 - 480 (2007/10/02)
The isomeric pairs+. and +. and +. and +. have been established as stable, noninterconverting structures.The conclusion derives from studies of collision induced decomposition spectra.The same conclusion pertains for the ions +. and +., and for +., +. and HNCCHCHCNH>+..The energy barrier of a -hydrogen shift, a possible isomerization mechanism, is determined to be at least 163kJ mol-1 for the +. and +. pair, and the barrier may be as high as 318kJ*mol-1.The C3H5N and C4H4N2 radical cations decompose before they can be activated with 318 kJ mol-1 of internal energy.
