Formation and stability of gaseous tolyl ions

Collisional activation mass spectra confirm that tolyl ions can be produced from a variety of CH₃C₆H₄Y compounds. High purity o-, m- and p-tolyl ions are prepared by chemical ionization of the corresponding fluorides (Y=F) as proposed by Harrison. In electron ionization of CH₃C₆H₄Y formation of the more stable tropylium and benzyl ionic isomers usually accompanies that of the o-, m- and p-tolyl ions. Isomerization of low energy [CH₃C₆H₄Y]⁺? to [Y–methylenecyclohexadiene]⁺? is proposed to account for most [benzyl]⁺ formation, while the tropylium ion appears to arise from the isomerization of tolyl ions formed with higher internal energies, [o-, m-, p-tolyl]⁺→ [benzyl]⁺→ [tropylium]⁺, consistent with Dewar's predictions from MINDO/3 calculations.     

Theoretical studies on the structure and protonation of Cu(II) complexes of a series of tripodal aliphatic tetraamines: Good correlations with the experimental data

DFT(B3LYP) studies on first protonation step of a series of Cu(II) complexes of some tripodal tetraamines with general formula N[(CH₂)_nNH₂][(CH₂)_mNH₂][(CH₂)_pNH₂] (n = m = p = 2, tren; n = 3, m = p = 2, pee; n = m = 3, p = 2, ppe; n = m = 3, tpt; n = 2, m = 3, p = 4, epb; and n = m = 3, p = 4; ppb) are reported. First, the gas‐phase proton macroaffinity of all latter complexes was calculated with considering following simple reaction: [Cu(L)]²⁺(g) + H⁺(g) → [Cu(HL)]³⁺(g). The results showed that there is a good correlation between the calculated proton macroaffinities of all complexes with their stability constants in solution. Then, we tried to determine the possible reliable structures for microspecies involved in protonation process of above complexes. The results showed that, similar to the solid state, the [Cu(L)(H₂O)]²⁺ and [Cu(HL)(H₂O)₂]³⁺ are most stable species for latter complexes and their protonated form, respectively, at gas phase. We found that there are acceptable correlations between the formation constants of above complexes with both the ? and ? of following reaction: [Cu(L)(H₂O)]²⁺(g) + H⁺(g) + H₂O(g) → [Cu(HL)(H₂O)₂]³⁺(g). The ? of the latter reaction can be defined as a theoretically solvent–proton macroaffinity of reactant complexes because they have gained one proton and one molecule of the solvent. The unknown formation constant of [Cu(epb)]²⁺ complex was also predicted from the observed correlations. In addition, the first proton affinity of all complexes was studied in solution using DPCM and CPCM methods. It was shown that there is an acceptable correlation between the solvent–proton affinities of [Cu(L)(H₂O)]²⁺ complexes with formation constants of [Cu(HL)(H₂O)₂]³⁺ complexes in solution. © 2010 Wiley Periodicals, Inc. J Comput Chem, 2010     

Metastable ion and induced stable ion fragmentation of isomeric 5-methyl-3-tolyl-1,2,4-oxadiazoles

The electron ionization fragmentation patterns of 5-methyl-3-(o-, m- and p-tolyl)-1,2,4-oxadiazoles (1a—c) have been examined by metastable ion and high resolution mass spectrometry. The o-tolyl isomer loses CO and C₂H₂O from the metastable molecular ion whereas the m- and p-tolyl isomers lose only CH₃CN thus indicating a strong ortho effect in directing the fragmentation in 1a. Slight differences between o-, m- and p-tolyl isomers in the collisional activation fragmentation of stable [C₇H₆N]⁺ ions suggest that structural differences exist even after a series of extensive rearrangements of the molecular ions. Metastable ion kinetic energy (MIKE) and collisional activation (CA) spectra were very helpful in providing valuable information about many fragments.     

Synthesis of porphyrinyl-nucleosides

Several porphyrinyl-nucleosides were prepared in the reaction of the OH group of one, two or four meso-p-hydroxyphenyl substituents of porphyrin with 5′-O-tosylates of 2′,3′-O-isopropylidene-adenosine or -uridine, or 5′-O-tosylthymidine; the remaining porphyrin meso-substituents were p-tolyl, p-hydroxyphenyl or 4-pyridyl. The following porphyrinyl-nucleosides were obtained with 8–17% yield: meso-di(p-tolyl)di(p-phenylene-5′-O-2′,3′-O-isopropylidene-adenosine) (or -uridine)porphyrins 1,2 , the respective meso-tetranucleosideporphyrins 3,4 -meso-mono(p-phenylene-5′-O-thymidine)porphyrins 5–7 , meso-di(p-tolyl)di(p-phenylene-5′-O-thymidine)porphyrins 8,9 and the meso-di(p-hydroxyphenyl)di(p-phenylene-5′-O-thymidine)porphyrins 10. Other compounds prepared belonged to the series: meso(4-pyridyl)_4?n(p-phenylene-5′-O-2′,3′-O-isopropylideneuridine)_nporphyrin, n = 1, 2 or 4, 11–13. N-Methylation gave the water soluble iodide salts: (N-methyl-4-pyridinium)4_4?n(p-phenylene-5′-O-2′,3′-isopropylideneuridine)_nporphyrins, n = 1, 2 or 4, 14–16. The ms fab showed in most cases stepwise detachment of the CH₂(5′)-nucleoside fragments. The porphyrins meso disubstituted by thymidine represent a convenient substrate for the build-up of both nucleoside units into the oligo/polynucleotide chains.     

Electron impact ionization of ethylene–methanol heteroclusters: Stable configurations and mechanisms in intracluster ion–molecule reactions

Reactions that proceed within mixed ethylene–methanol cluster ions were studied using an electron impact time-of-flight mass spectrometer. The ion abundance ratio, [(C₂H₄)_n(CH₃OH)_mH⁺]/[(C₂H₄)_n(CH₃OH)_m⁺], shows a propensity to increase as the ethylene/methanol mixing ratio increases, indicating that the proton is preferentially bound to a methanol molecule in the heterocluster ions. The results from isotope-labelling experiments indicate that the effective formation of a protonated heterocluster is responsible for ethylene molecules in the clusters. The observed (C₂H₄)_n(CH₃OH)_m⁺ and (C₂H₄)_n(CH₃OH)_m–1CH₃O⁺ ions are interpreted as a consequence of the ion–neutral complex and intracluster ion–molecule reaction, respectively. Experimental evidence for the stable configurations of heterocluster species is found from the distinct abundance distributions of these ions and also from the observation of fragment peaks in the mass spectra. Investigations on the relative cluster ion distribution under various conditions suggest that (C₂H₄)_n(CH₃OH)_mH⁺ ions with n + m ≤ 3 have particularly stable structures. The result is understood on the basis of ion–molecule condensation reactions, leading to the formation of fragment ions, $ {\rm CH}_2=\!=\mathop {\rm O}\limits^ + {\rm CH}_3 $ and (CH₃OH)H₃O⁺, and the effective stabilization by a polar molecule. The reaction energies of proposed mechanisms are presented for (C₂H₄)_n(CH₃OH)_mH⁺(n + m ≤ 3) using semi-empirical molecular orbital calculations.     

Polymerization of acrylonitrile by catalytic systems consisting of triphenylphosphine and a lewis acid

Polymerization of acrylonitrile in the presence of systems that consisted of triphenylphosphine (PPh₃) and a Lewis acid R_mMX_n (ZnCl₂, Me₃Al, Et₃Al, Et₂AlCl, EtAlCl₂, AlCl₃) was studied. The systems that contained Me₃Al and Et₃Al (i.e., Lewis acid of moderate acidity) were the most efficient catalysts. Conductometric measurements carried out in the polymerization systems showed the presence of ions. The presence of phosphonium cation in the polyacrylonitrile chain formed by the PPh₃–R_mMX_n catalytic systems was determined by IR, ¹H-NMR, and ³¹P-NMR spectroscopy. The average molecular weight measurements and kinetic chain lengths of polyacrylonitrile formed within the reaction time in the presence of PPh₃–Et₃Al showed that transfer reactions occur. According to the results obtained, the polymerization reaction of acrylonitrile by PPh₃–R_mMX_n involved a zwitterion formed by the attack of PPh₃ on acrylonitrile complexed by Lewis acid [Ph₃P^⊕? CH₂? C^?H? C?N → MR_mX_n] and the anion [CH₂?C^?? C?N] formed by the proton abstraction from the monomer.     

Polyamides from α,ω-oxaalkanedioic acids having long methylene chain units

Three series of polyamides were prepared from diamines (hexamethylenediamine, bis-5-aminoamyl ether, p-xylylenediamine) and α,ω-oxaalkanedioic acids of formula HOOC(CH₂)_mO(CH₂)_nCOOH, where m = n = 3–10, in symmetric structures, but m = 3 or 4 in unsymmetric structures. The melting points of these polymers were plotted against the number of carbon atoms of the oxaalkylene groups. The melting points of polymers from each diamine fell on three different curves according to the structures of the dicarboxylic acids: symmetric ? (CH₂)_nO(CH₂)_n? ; unsymmetric ? (CH₂)₃O(CH₂)_n? , and unsymmetric ? (CH₂)₄O(CH₂)_n? . A minimum melting point is observed at about the same point of the acid structure in every curve of the unsymmetric dicarboxylic acids. The marked depression in the polymer melting points around the minimum point is attributed to the increase of the entropy of fusion.     

Zum basenkatalysierten H/D-Austausch des acetylenischen Wasserstoffatoms in aromatischen Alkinylverbindungen

On the Base-Catalysed H/D-Exchange of the Acetylenic Hydrogen Atom in Aromatic Alkynyl Compounds H/D-exchange rates for a number of compounds of the general type 1 (X = p-CH₃O, m-CH₃O, p-CF₃, m-CF₃, p-CH₃, p-Cl, H; Z ? O, NH, CH₂) were determined in N-methyl-pyrrolidine (NMP)/D₂O mixtures at 25° (see Table 1). It is shown that the log k values of the H/D-exchange correlate nicely (r = 0.995) with the chemical shift of the acetylenic proton in 1 . Thus, the H/D-exchange rate is given by log k (min^?1) = 2.91 · δ (ppm) - 7.79 for the NMP/D₂O mixture at 25°.     

Regioselective aerobic oxidation of bis-sulfides into monosulfoxides

The cobalt(II) acetylacetonate/aldehyde-promoted aerobic oxidation of three bis-sulfides of general formula R¹-SCH₂CH₂S-R², where R¹ is a heterocycle and R² is p-tolyl, provides a method to functionalise selectively the sulfur atom bonded to the p-tolyl moiety leading to the corresponding monosulfoxides. The same chemoselectivity and little diastereoisomeric excess (10%) was achieved by submitting to oxidative conditions the chiral bis-sulfide (S)-R³-SCH₂CH(CH₃)CH₂-SR⁴ (R³=benzothiazolyl, R⁴=p-tolyl).     

Reactions of trichloro(cyclopentadienyl)titanium(IV) with 1,5-diarylthiocarbazones

Summary The synthesis and characterization of the complexes from the reactions of trichloro(cyclopentadienyl)titanium(IV) with 1,5-diarylthiocarbazones (aryl=phenyl,o-tolyl,o-chlorophenyl,p-tolyl,p-chlorophenyl, or 3,5-dimethylphenyl) are reported. They are of the types CpTi(HDz)Cl₂ and CpTi(HDz)₂Cl (Cp=cyclopentadienyl, HDz^–=the mono-anion of a 1,5-diarylthiocarbazone, H₂Dz). The compounds are nonelectrolytes in dimethylformamide (DMF). In solid state, the far i.r. spectra of CpTi(HDz)Cl₂ indicate the complexes to be dimeric, involving Cl-bridges.     

Star-shaped polymers by living cationic polymerization. VII. Amphiphilic graft polymers of vinyl ethers with hydroxyl groups: Synthesis and host–guest interaction

Amphiphilic graft polymers of vinyl ethers (VEs) ( 6 ) where each branch consists of a hydrophilic polyalcohol and a hydrophobic poly(alkyl vinyl ether) segment were prepared on the basis of living cationic polymerization, and their properties and functions were compared with the corresponding amphiphilic star-shaped polymers. In toluene at ?15°C, the HI/ZnI₂-initiated living block polymer 2 of an ester-containing VE (CH₂? CHOCH₂CH₂OCOCH₃) and isobutyl VE (IBVE) was terminated with the diethyl 2-(vinyloxy)ethylmalonate anion [ 3 ; ^ΦC(COOEt)₂CH₂CH₂OCH ? CH₂] ( 2/3 = 1/2 mole ratio) to give a macromonomer ( 4 ), H[CH₂CH(OCH₂CH₂OCOCH₃)] _m-[CH₂CH(OiBu)]_n? C(COOEt)₂CH₂CH₂OCH ? CH₂ (m = 5, n = 15; M?_n = 2600, M?_w/M?_n = 1.13, 1.10 vinyl groups/chain). Subsequently, 4 was homopolymerized with HI/ZnI₂ in toluene at ?15°C. In 3 h, 85% of 4 was consumed and a graft polymer ( 5 ) was obtained [M?_w = 15000, DP_n (for 4 ) = 6]. The apparent M?_w (10,900) of 5 by size-exclusion chromatography (SEC) is smaller than that by light scattering as well as that (18,300) by SEC of the corresponding linear polymer with the almost same molecular weight, indicating the formation of a multi-branched structure. Hydrolysis of the pendant esters in 5 gave the amphiphilic graft polymer 6 where each branch consists of a hydrophilic polyalcohol and a hydrophobic poly(IBVE) segment. The graft polymer 6 was found to interact specifically with small organic molecules (guests) with polar functional groups, and 6 differed in solubility and host-guest interaction from the corresponding star-shaped polymer. © 1993 John Wiley & Sons, Inc.     

Energetics of proton transfer between carbon atoms (H3CH ? CH3)−

Ab initio calculations were carried out to study the potential energy surface of (H₃C? H? CH₃)^?. The 6–31G* basis set is supplemented by a set of diffuse p functions on both C and H (with a range of exponents for the latter). The binding energy of CH₄ and CH₃^? to form the (H₃CH? CH₃)^? complex is about 2 kcal/mol, much smaller than for comparable ionic H-bonded systems involving O or N atoms. Nearly half of this interaction energy is due to correlation effects, computed at second and third orders of Møller-Plesset perturbation theory. Correlation is also responsible for substantial reductions in the energy barrier to proton transfer within the complex. This barrier is computed to be 13?15 kcal/mol at the MP3 level, depending upon the exponent used for the H p functions.     

Mass spectrometric monitoring of oxidation of aliphatic C6–C8 hydrocarbons and ethanol in low pressure oxygen and air plasmas

Experimental and theoretical studies on the oxidation of saturated hydrocarbons (n‐hexane, cyclohexane, n‐heptane, n‐octane and isooctane) and ethanol in 28 Torr O₂ or air plasma generated by a hollow cathode discharge ion source were made. Ions corresponding to [M + 15]⁺ and [M + 13]⁺ in addition to [M ? H]⁺ and [M ? 3H]⁺ were detected as major ions where M is the sample molecule. The ions [M + 15]⁺ and [M + 13]⁺ were assigned as oxidation products, [M ? H + O]⁺ and [M ? 3H + O]⁺, respectively. By the tandem mass spectrometry analysis of [M ? H + O]⁺ and [M ? 3H + O]⁺, H₂O, olefins (and/or cycloalkanes) and oxygen‐containing compounds were eliminated from these ions. Ozone as one of the terminal products in the O₂ plasma was postulated as the oxidizing reagent. As an example, the reactions of C₆H₁₄^+? with O₂ and of C₆H₁₃⁺ (CH₃CH₂CH⁺CH₂CH₂CH₃) with ozone were examined by density functional theory calculations. Nucleophilic interaction of ozone with C₆H₁₃⁺ leads to the formation of protonated ketone, CH₃CH₂C(=OH⁺)CH₂CH₂CH₃. In air plasma, [M ? H + O]⁺ became predominant over carbocations, [M ? H]⁺ and [M ? 3H]⁺. For ethanol, the protonated acetic acid CH₃C(OH)₂⁺ (m/z 61.03) was formed as the oxidation product. The peaks at m/z 75.04 and 75.08 are assigned as protonated ethyl formate and protonated diethyl ether, respectively, and that at m/z 89.06 as protonated ethyl acetate. Copyright © 2016 John Wiley & Sons, Ltd.     

Synthesis of highly reactive polyisobutylenes with exo‐olefin terminals via controlled cationic polymerization with H2O/FeCl3/iPrOH initiating system in nonpolar hydrocarbon media

Cationic polymerizations of isobutylene (IB) with H₂O/FeCl₃/isopropanol (iPrOH) initiating system were conducted in nonpolar hydrocarbon media, such as n‐hexane or mixed C₄ fractions at ?40 to 20 °C. This cationic polymerization is a chain‐transfer dominated process via highly selective β‐proton elimination from ? CH₃ in the growing chain ends, leading to formation of highly reactive polyisobutylenes (HRPIBs) with large contents (> 90 mol %) of exo‐olefin end groups (structure A ). The content of structure A remained nearly constant at about 97 mol % during polymerization and isomerization via carbenium ion rearrangement could be suppressed in nonpolar media. First‐order kinetics with respect to monomer concentration was measured for selective cationic polymerization of IB in the mixed C₄ fraction feed at ?30 °C and the apparent rate constant for propagation was 0.028 min^?1. High polymerization temperature (T_p) or [FeCl₃] accelerate β‐proton elimination or isomerizations and simultaneously decrease selectivity of β‐proton abstraction from ? CH₃. Molecular weight decreased and molecular weight distribution (MWD) became narrow with increasing T_p or [FeCl₃]. To the best of our knowledge, this is the first example to achieve high quality HRPIBs with near 100% of exo‐olefin terminals and relatively narrow MWD (M_w/M_n = 1.8) by a single‐step process in nonpolar hydrocarbon media. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013 , 51, 4200–4212     

Reaction of tetramethyl-1,2-dioxetane with triphenylphosphine: Activation parameters for the formation of 2,2-dihydro-4,4,5,5-tetramethyl-2,2,2-triphenyl-1,3,2-dioxaphospholane

The reaction of tetramethyl-1,2-dioxetane ( 1 ) and triphenylphosphine ( 2 ) in benzene-d₆ produced 2,2-dihydro-4,4,5,5-tetramethyl-2,2,2-triphenyl-1,3,2-dioxaphospholane ( 3 ) in ?90% yield over the temperature range of 6–60°. Pinacolone and triphenylphosphine oxide ( 4 ) were the major side products [additionally acetone (from thermolysis of 1 ) and tetramethyloxirane ( 5 ) were noted at the higher temperatures]. Thermal decomposition of 3 produced only 4 and 5 . Kinetic studies were carried out by the chemiluminescence method. The rate of phosphorane was found to be first order with respect to each reagent. The activation parameters for the reaction of 1 and 2 were: Ea ? 9.8 ± 0.6 kcal/mole; ΔS^≠ = ?28 eu; k_30° = 1.8 m^?1sec^?1 (range = 10–60°). Preliminary results for the reaction of 1 and tris (p-chlorophenyl)phosphine were: Ea ? 11 kcal/mole, ΔS^≠ = ?24 eu, k_30° = 1.3 M^?1sec^?1 while those for the reaction of 1 and tris(p-anisyl)phosphine were: Ea ? 8.6 kcal/mole, ΔS^≠ = ?29 eu, k_30° = 4.9 M^?1 sec^?1.     

Zur Photochemie von 3,5-Diaryl-2-isoxazolinen. 30. Mitteilung über Photoreaktionen

Irradiation of 3,5-diphenyl- or 3-(p-tolyl)-5-phenyl-2-isoxazoline ( 12 and 13 , respectively) in benzene with a high-pressure mercury lamp yields 4,5-diphenyl- or 4-(p-tolyl)-5-phenyl-3-oxazoline ( 17 and 19 , respectively) and the β-amino-chalcones 18 or 20 in addition to benzaldehyde, benzonitrile and p-tolunitrile, respectively (scheme 6 and ‘Anmerkg.’ p. 2600). The 3-oxazolines 17 and 19 are formed by route a (scheme 8) via 3-phenyl- or 3-(p-tolyl)-2H-azirine ( 23 , R = H and CH₃, respectively) and their photochemically rearranged successors, the nitrile methylides 24 , as intermediates. The discovery of this reaction has served as a basis for the quickly developing photochemistry of 3-aryl-2H-azirines [2] [24]. Photolysis of the 2-isoxazoline 13 in methanol leads to the formation of a mixture of syn/anti-p-tolyl trans-styryl ketoximes (syn/anti, trans- 30 ) and anti, cis- 30 , 2-(p-tolyl)-quinoline ( 29 ), the 4-hydroxymethylated derivative 32 of the latter (in small amounts), besides the β-aminochalcone 20 , benzaldehyde, p-tolualdehyde and p-tolunitrile (scheme 9). It could be shown that the stereoisomeric ketoximes 30 are photochemically interconvertible (scheme 12) and that at least one mechanism of formation of 2-(p-tolyl)-quinoline ( 29 ) is the photo-induced cyclisation of p-tolyl-cis-styryl ketoximes (cis- 30 ) (scheme 13). A tentative mechanism for the formation of p-tolual-dehyde is given in scheme 10; the crucial step is the protonation of p-tolunitrile methylide ( 24 , R = CH₃) by methanol at the nitrile carbon atom, after which hydrolysis yields the aldehyde.     

New interpretation of progression bands observed in infrared spectra of nylon‐m/n

A series of progression bands observed in the infrared spectra of nylon‐m/n and their model compounds have been interpreted in a new manner on the basis of simply coupled oscillator models of zigzag alkyl chains. Nylon‐m/n possesses the methylene sequences of (CH₂)_m and (CH₂)_n?2, and so the effective models of m and n ? 2 coupled oscillators, respectively, had previously been assumed for the methylene rocking–twisting mode, for example. However, the spectral patterns of progression bands predicted by this previously proposed model have been found to be inconsistent with those observed for many kinds of nylon samples with various m and n values. It is rather reasonable to assume that the effective numbers of oscillators should be m ? 2 and n ? 4 for the methylene rocking, twisting, and wagging modes of the (CH₂)_m and (CH₂)_n?2 sequences, respectively. In other words, the infrared progression bands observed for methylene local modes of nylon‐m/n may be interpreted reasonably with the data of n‐alkane molecules with the chemical formulae CH₃(CH₂)_m?2CH₃ and CH₃(CH₂)_n?4CH₃. For the C? C stretching modes, the equivalent n‐alkanes are CH₃(CH₂)_m?1CH₃ and CH₃(CH₂)_n?3CH₃, respectively. In the simply coupled oscillator model, the vibrational mode of one methylene group is represented by an oscillator, for example. Our new concept is to isolate the terminal oscillator adjacent to the amide group from the other oscillators in the inner parts of the methylene zigzag sequence. This corresponds to a physical situation in which the methylene group adjacent to the amide group shows a different vibrational behavior of larger amplitude than those of the inner methylene sequence, as supported by broad‐line NMR data and molecular dynamics calculations reported in the literature. Another possibility is a difference in the electron structure of the methylene unit adjacent to the amide group from that of the inner methylene sequence, resulting in a difference in the force constant and giving a vibrational decoupling between these two types of methylene units. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 1294–1307, 2003     

Wetting properties of bis(trifluoromethyl)carbinyl acrylate polymers

A series of bis(trifluoromethyl)carbinyl acrylate monomers [Y-C(CF₃)₂ O? CO? CH?CH₂] in which Y is CH₃, CH₃CH₂, CH₃CH₂CH₂, CH₃CH₂CH₂CH₂, C₆H₅, H, F, CF₃, N₃, CN, and CH₃OCH₂CH₂O, was prepared. Polymers were easily prepared from all of these monomers except where Y = CN, wherein a variety of initiation methods failed to produce high molecular polymer. Wettabilities of the polymer films were examined by means of contact angle measurements by using n-alkane test liquids and water. Values of the dispersion force contribution (γs^d) and the polar force contribution (γs^p) to the solid surface energy were calculated by employing both geometric and harmonic mean approximations. Values of γs^d calculated by either method agreed well with γ_c (critical surface tension) values determined graphically from contact angle data employing n-alkane test liquids, confirming the suggestion that γ_c is an approximate measure of the dispersion force contribution to solid surface energy. Values of γs_d ranged from 15 dyne/cm (Y = F or CF₃) to 25 dyne/cm (Y = C₆H₅). Values of the polar force contribution to solid surface energy (γs^p) varied from 0.6 dyne/cm (Y = CH₃CH₂CH₂CH₂) to 3.4 dyne/cm (Y = CH₃OCH₂CH₂O) when calculated by the geometric mean equation. The values of γs^p obtained from the harmonic mean equation followed the same trend upon varying substituents, but were larger in value, ranging from 2.9 dyne/cm (Y = CH₃CH₂CH₂CH₂) to 7.5 dyne/cm (Y γ CH₃OCH₂CH₂O).     

Living Carbocationic Polymerization. LVII. Kinetic Treatment of Living Carbocationic Polymerization Mediated by the Common Ion Effect

Abstract

The effect of anion concentration on the apparent rate constant of polymerization k^A _p of isobutylene (IB) induced by the 2-chloro-2,4,4-trimethylpentane (TMPCl)/TiCl₄ initiating system using the CH₂Cl₂/nC₆H₁₄ (60/40 v/v) solvent system at ?40 and ?80°C was studied by the use of nBu₄NCl. Computer simulation has shown that k^A _p decreases several orders of magnitude upon the addition of even a very small amount of common anion TiCl^?- ₅ to the charge. The rate of change is reduced in the concentration range of experimental interest. It was concluded that the decrease of k^A _p with increasing TiCl ^?- ₅ concentration is mainly due to the decreasing contribution of propagation by free ions. The contribution (%) of propagation by free ions to the apparent rate of propagation was calculated.     

Metalmetal bonded triazenido compounds : II. Compounds with M = RhI,IrI; R = Me,aryld and X = Cl,Br, I Cl,Br, I

Complexes

(M = Rh, X = Cl, M = Ir, X = Cl, Br, I and R = CH₃, R′ = CH₃, p-tolyl) have been made by the reaction of (Ph₃P)₂(CO)MX with

. The proposed structure is analogous to that of the related copper derivatives and contains a five-membered ring in which an M^I to Ag^I donor bond is bridged by an azenido group, while the halide atom X has migrated from M^I to Ag^I.Carbon monoxide at 1 atm reacts rapidly and quantitatively with the iridium compounds to give novel acyltriazenido compounds {Ph₃P(CO)₂ - Ir[OCN(R)N=NR′]} (R = CH₃, p-tolyl; R′ = CH₃, p-tolyl).