Synthesis of 3-pyrrol-3′-yloxindoles with a carbamate function

By the reaction of methyl {4(3)-[2-(2-oxo-1,2-dihydro-3H-indol-3-ylidene)acetyl]phenyl} carbamates with ethyl 3-aminocrotonate at boiling in the mixture toluene-anhydrous ethanol, 2: 1, ethyl 5-{3(4)-[(methoxycarbonyl)amino]phenyl}-2-methyl-4-(2-oxo-2,3-dihydro-1H-indol-3-yl)-1H-pyrrole-3-carboxylates were obtained. The condensation of methyl {3(4)-[2-(2-oxo-1,2-dihydro-3H-indol-3-ylidene)acetyl] phenyl}carbamates with ethyl acetoacetate in the presence of ammonium acetate and 20 mol% of 1-methyl-3-butylimidazolium chloride or 1-methyl-3-octylimidazolium tetrafluoroborate at boiling in anhydrous ethanol led to the formation of the corresponding 3-pyrrol-3′-yloxindoles with a carbamate function.     

Novel Juvenoids of the 2-(4-hydroxybenzyl)cyclohexan-1-one Series

A series of insect juvenile hormone analogs (juvenoids) was synthesized and studied. The basic skeleton of these juvenoids contains three rings and a short aliphatic subunit and bears two or three chiral centers (depending on the appropriate structure; see 6–9 ). The chiral center located in the 1,2-diphenoxypropane subunit has the configuration (RS), (R) ( a series), or (S) ( b series). The juvenoids were subjected to a biological screening, the preliminary results of which are briefly described.     

Polymerization of ethylene with self-immobilizing bis(phenoxyimine) catalytic systems

The kinetic features of polymerization of ethylene with five methylaluminoxane-activated selfim-mobilizing bis(phenoxyimine) complexes of titanium chloride, namely, bis{2-[(4-allyloxyphenylimino)methyl]-6-tert-butylphenoxy}TiCl₂, bis{2-[(4-allyloxyphenylimino)methyl]-4,6-di-tert-butylphenoxy}TiCl₂, bis{2-[(4-allyloxyphenylimino)methyl]-6-cumylphenoxy}TiCl₂, bis{2-[(4-allyloxyphenylimino)methyl]-4,6-dicumylphenoxy}TiCl₂, and bis{2-[(4-allyloxyphenylimino)methyl]-6-1-(4-tert-butylphenyl)ethylphenoxy}TiCl₂ have been studied. The activity of these complexes in the polymerization of ethylene in the temperature range 20–80°C and an ethylene pressure of 0.3 MPa has been investigated both in the homogeneous and polymer matrix-bound states. The self-immobilizing catalytic systems possess high activity (up to 40000 kg_PE/mol_cat MPa h) and give rise to ultrahigh-molecular-weight PE (M = (2–7) × 10⁶) with an improved morphology of polymer particles.     

The reactions of methyl radicals with atomic and molecular oxygen

The reaction of methyl radicals with atomic and molecular oxygen was studied with a photoionization mass spectrometer. The methyl radicals were generated by reacting oxygen atoms with ethylene in a fast-flow tube reactor. The rate constant for the reaction of methyl radicals with oxygen atoms was (1.0 ± 0.2) × 10^?10 cm³/molec · sec with no significant variation with temperature over the range of 259–341°K. The reaction of methyl radicals with molecular oxygen involves both a two-body reaction, having a rate constant \documentclass{article}\pagestyle{empty}\begin{document}$\begin{array}{*{20}c} {k_{{\rm 3a}} = (10^{- 12.54 \pm 0.35})\exp [(- 940 \pm 250)T^{- 1}]} & {{\rm cm}^{\rm 3} /{\rm molec} \cdot {\rm sec}} \end{array}$\end{document} and a three-body recombination having a negative temperature dependence. The methyl peroxy radical could be observed at its steady-state concentration. The rate constants determined at low pressures are compatible with the values determined at higher pressures by flash photolysis. Formaldehyde appears to be a major product of the two-body reaction of CH₃ with O₂, and also of the reaction of CH₃O₂ with oxygen atoms.     

Halocyclization of 2-(2-{4-[allylamino(thioxo)methyl]piperazin-1-yl}ethyl)-1<Emphasis Type="Italic">H</Emphasis>-benzo[<Emphasis Type="Italic">de</Emphasis>]isoquinoline-1,3(2<Emphasis Type="Italic">H</Emphasis>)-dione

Cyclization of 2-(2-{4-[allylamino(thioxo)methyl]piperazin-1-yl}ethyl)-1H-benzo[de]isoquinoline-1,3(2H)-dione by the action of iodine, bromine, or sulfuryl chloride gave 2-(2-{4-[4,5-dihydro-5-(halomethyl)-thiazol-2-yl]piperazin-1-yl}ethyl)-1H-benzo[de]isoquinoline-1,3(2H)-dione hydrohalides which were converted into 2-{2-[4-(5-methylthiazol-2-yl)piperazin-1-yl]ethyl}-1H-benzo[de]isoquinoline-1,3(2H)-dione.     

Synthesis of new functionally substituted hetarylcarbamates from methyl {4-[(2<Emphasis Type="Italic">E</Emphasis>)-3-(4-methoxyphenyl)-prop-2-enoyl]phenyl}carbamate

Three-component condensation of methyl {4-[(2E)-3-(4-methoxyphenyl)prop-2-enoyl]phenyl}- carbamate with ninhydrin and L-proline in methanol–water (10: 1) afforded methyl {4-[1,3-dioxo-1′- (4-methoxyphenyl)-1,1′,2′,3,5′,6′,7′,7a′-octahydrospiro[indene-2,3′-pyrrolizin]-2′-ylcarbonyl]phenyl}carbamate. Heating of methyl {4-[(2E)-3-(4-methoxyphenyl)prop-2-enoyl]phenyl}carbamate with isatin and benzylamine in methanol gave methyl {4-[4′-(4-methoxyphenyl)-2-oxo-5′-phenyl-1,2-dihydrospiro[indole-3,2′-pyrrolidin]-3′-ylcarbonyl]phenyl}carbamate. The condensation of methyl {4-[(2E)-3-(4-methoxyphenyl)prop-2- enoyl]phenyl}carbamate with sarcosine and 11H-indeno[1,2-b]quinoxalin-11-one generated in situ from ninhydrin and o-phenylenediamine in boiling ethanol led to the formation of methyl {4-[4′-(4-methoxyphenyl)-1′-methyl-11,11a-dihydro-5aH-spiro[benzo[b]phenazine-6,2′-pyrrolidin]-3′-ylcarbonyl]phenyl}carbamate.     

Synthesis and Structure-Activity Relationships of Juvenoids Derived from 2-(4-hydroxybenzyl)cycloalkan-1-ones

Juvenoids 16–30, 32, 36, 38–41, 44–46 , and 49–56 containing carbamate, carbonate, and urea moieties in the molecule were synthesized and subjected to a biological screening (Schemes 2–7, Table 2). Carbamate juvenoids 1–4 were used as reference compounds for a detailed structure-activity study of their analogues. A clear relationship between the nature of the side chain functional group and the biological activity was found. Surprisingly, not only the juvenoids 1–4 but also 38–41 , the compounds with a reversed carbamate N,O-substitution pattern, showed very promising biological activity. In contrast, the carbonate and urea derivatives displayed a remarkably low activity. The relationship between the size and substitution at atoms C(2) and C(3) of the saturated ring and the biological activity is very complex and is still not completely understood.     

Magnesium chloride supported high mileage catalysts for olefin polymerization. XXI. Isospecific and regiospecific vanadium catalyst for propylene polymerization

Several CW–V catalysts were prepared by supporting VCl₄ on Mg Cl₂ with ethyl benzoate and CH–V catalysts prepared by reacting MgCl₂.ROH, phthalic anhydride, and VCl₄. These vanadium catalysts, activated with TEA (triethyl aluminum)/MPT (methyl-p-toluate) produce mainly (88–96%) refluxing n-heptane insoluble isotactic PP. The active site has $ k_{p,i} = 1580 \left( M {\rm s} \right)^{ - 1}, k_{tr,i}^{\rm A} = 2 \times 10^{ - 3} {\rm s}^{ - 1} , k_{tr}^{\rm H} = 3.8 \times 10^{ - 2} \left( {\rm torr} \right)^{ - {1 \mathord{\left/ {\vphantom {1 2}} \right. \kern-\nulldelimiterspace} 2}} {\rm s}^{ - 1}$ for the isospecific ones and $ k_{p,a} = 58 \left( M {\rm s} \right)^{ - 1} ,k_{tr,a}^{\rm A} = 3 \times 10^{ - 3} {\rm s}^{ -1}$ for the nonspecific sites. Catalyst of VCl₃ supported on MgCl₂ has comparable productivity as the VCl₄/MgCl₂ catalyst but catalyst of VCl₂ supported on MgCl₂ exhibit only one-ninth of the productivity. Extensive comparison has been made between the CW–V and the CW–Ti systems which revealed striking similarities between their polymerization behaviors. MgCl₂ exerts profound influence on the stereochemical control of the vanadium ion on its activity for monomer coordination and insertion.     

Four NiII complexes with the new cyclam–methylimidazole ligand 1‐[(1‐methyl‐1H‐imidazol‐2‐yl)methyl]‐1,4,8,11‐tetraazacyclotetradecane

Although it has not proved possible to crystallize the newly prepared cyclam–methylimidazole ligand 1‐[(1‐methyl‐1H‐imidazol‐2‐yl)methyl]‐1,4,8,11‐tetraazacyclotetradecane (L^Im1), the trans and cis isomers of an Ni^II complex, namely trans‐aqua{1‐[(1‐methyl‐1H‐imidazol‐2‐yl)methyl]‐1,4,8,11‐tetraazacyclotetradecane}nickel(II) bis(perchlorate) monohydrate, [Ni(C₁₅H₃₀N₆)(H₂O)](ClO₄)₂·H₂O, (1), and cis‐aqua{1‐[(1‐methyl‐1H‐imidazol‐2‐yl)methyl]‐1,4,8,11‐tetraazacyclotetradecane}nickel(II) bis(perchlorate), [Ni(C₁₅H₃₀N₆)(H₂O)](ClO₄)₂, (2), have been prepared and structurally characterized. At different stages of the crystallization and thermal treatment from which (1) and (2) were obtained, a further two compounds were isolated in crystalline form and their structures also analysed, namely trans‐{1‐[(1‐methyl‐1H‐imidazol‐2‐yl)methyl]‐1,4,8,11‐tetraazacyclotetradecane}(perchlorato)nickel(II) perchlorate, [Ni(ClO₄)(C₁₅H₃₀N₆)]ClO₄, (3), and cis‐{1,8‐bis[(1‐methyl‐1H‐imidazol‐2‐yl)methyl]‐1,4,8,11‐tetraazacyclotetradecane}nickel(II) bis(perchlorate) 0.24‐hydrate, [Ni(C₂₀H₃₆N₆)](ClO₄)₂·0.24H₂O, (4); the 1,8‐bis[(1‐methyl‐1H‐imidazol‐2‐yl)methyl]‐1,4,8,11‐tetraazacyclotetradecane ligand is a minor side product, probably formed in trace amounts in the synthesis of L^Im1. The configurations of the cyclam macrocycles in the complexes have been analysed and the structures are compared with analogues from the literature.     

New (S)-proline derivatives as catalysts for the enantioselective aldol reaction

(2S)-N- 2-[(R)-Hydroxy(phenyl)methyl]phenylpyrrolidine-2-carboxamide, (2 S)-N-{2-[(S)-hydroxy(phenyl)methyl]phenyl}pyrrolidine-2-carboxamide, and (S)-N-{2-[hydroxy-(diphenyl)methyl]phenyl}pyrrolidine-2-carboxamide were obtained and tested as catalysts for an asymmetric aldol reaction of 4-nitrobenzaldehyde with acetone.     

Facile addition of methyl lithium to a 4-vinylpyridine system

The rapid addition of methyl lithium to the 4-vinylpyridine system present in 4-{2,6-dihydroxy-4-(3-methyl-2-octyl)phenyl}-2-methyl-4-(4-pyridyl)but-3-en-2-ol ( 2 ) is reported. The α and β-4-{2,6-dihydroxy-4-(3-methyl-2-octyl)phenyl}-2,3-dimethyl-4-(4-pyridyl)butan-2-ols 4 and 5 formed, are cyclised by heating with 5N hydrochloric acid to trans and cis-3,4-dihydro-5-hydroxy-7-(3-methyl-2-octyl)-4-(4-pyridyl)-2,2,3-trimethyl-2H-1-benzopyran 6 and 7 respectively.     

Synthesis and characterization of poly(p-phenylene pyromellitamic acid)

Poly(p-phenylene pyromellitamic acid)s were synthesized over the weight-average molecular weight range 8,000 to 22,000. The polymers were recovered as amorphous powders composed of 3–4 × 1–2 μ platelets 0.1–0.2 μ thick containing 20–30% associated solvent. Consumption of reactants and attainment of the ultimate molecular weight of the polymer were found to occur within the first few minutes of reaction. The polymers were characterized by scanning electron microscopy; ultraviolet, visible, near-infrared, and infrared spectroscopy; x-ray analysis; viscometry; and light-scattering photometry. The intrinsic viscosity–molecular weight relation for the polymer in DMF was \documentclass{article}\pagestyle{empty}\begin{document}$ [\eta ] = 25.2 \times 10^{ - 4} \bar M_w^{0.56} $\end{document}.     

Three AgI,CuI and CdII coordination polymers based on the new asymmetrical ligand 2‐{4‐[(1H‐imidazol‐1‐yl)methyl]phenyl}‐5‐(pyridin‐4‐yl)‐1,3,4‐oxadiazole: syntheses,characterization and emission properties

The new asymmetrical organic ligand 2‐{4‐[(1H‐imidazol‐1‐yl)methyl]phenyl}‐5‐(pyridin‐4‐yl)‐1,3,4‐oxadiazole ( L , C₁₇H₁₃N₅O), containing pyridine and imidazole terminal groups, as well as potential oxdiazole coordination sites, was designed and synthesized. The coordination chemistry of L with soft Ag^I, Cu^I and Cd^II metal ions was investigated and three new coordination polymers (CPs), namely, catena‐poly[[silver(I)‐μ‐2‐{4‐[(1H‐imidazol‐1‐yl)methyl]phenyl}‐5‐(pyridin‐4‐yl)‐1,3,4‐oxadiazole] hexafluoridophosphate], {[Ag( L )]PF₆}_n, catena‐poly[[copper(I)‐di‐μ‐iodido‐copper(I)‐bis(μ‐2‐{4‐[(1H‐imidazol‐1‐yl)methyl]phenyl}‐5‐(pyridin‐4‐yl)‐1,3,4‐oxadiazole)] 1,4‐dioxane monosolvate], {[Cu₂I₂( L )₂]·C₄H₈O₂}_n, and catena‐poly[[[dinitratocopper(II)]‐bis(μ‐2‐{4‐[(1H‐imidazol‐1‐yl)methyl]phenyl}‐5‐(pyridin‐4‐yl)‐1,3,4‐oxadiazole)]–methanol–water (1/1/0.65)], {[Cd( L )₂(NO₃)₂]·2CH₄O·0.65H₂O}_n, were obtained. The experimental results show that ligand L coordinates easily with linear Ag^I, tetrahedral Cu^I and octahedral Cd^II metal atoms to form one‐dimensional polymeric structures. The intermediate oxadiazole ring does not participate in the coordination interactions with the metal ions. In all three CPs, weak π–π interactions between the nearly coplanar pyridine, oxadiazole and benzene rings play an important role in the packing of the polymeric chains.     

The coordination chemistry of two symmetric double‐armed oxadiazole‐bridged organic ligands with copper salts

Two new symmetric double‐armed oxadiazole‐bridged ligands, 4‐methyl‐{5‐[5‐methyl‐2‐(pyridin‐3‐ylcarbonyloxy)phenyl]‐1,3,4‐oxadiazol‐2‐yl}phenyl pyridine‐3‐carboxylate (L1) and 4‐methyl‐{5‐[5‐methyl‐2‐(pyridin‐4‐ylcarbonyloxy)phenyl]‐1,3,4‐oxadiazol‐2‐yl}phenyl pyridine‐4‐carboxylate (L2), were prepared by the reaction of 2,5‐bis(2‐hydroxy‐5‐methylphenyl)‐1,3,4‐oxadiazole with nicotinoyl chloride and isonicotinoyl chloride, respectively. Ligand L1 can be used as an organic clip to bind Cu^II cations and generate a molecular complex, bis(4‐methyl‐{5‐[5‐methyl‐2‐(pyridin‐3‐ylcarbonyloxy)phenyl]‐1,3,4‐oxadiazol‐2‐yl}phenyl pyridine‐3‐carboxylate)bis(perchlorato)copper(II), [Cu(ClO₄)₂(C₂₈H₂₀N₄O₅)₂], (I). In compound (I), the Cu^II cation is located on an inversion centre and is hexacoordinated in a distorted octahedral geometry, with the pyridine N atoms of two L1 ligands in the equatorial positions and two weakly coordinating perchlorate counter‐ions in the axial positions. The two arms of the L1 ligands bend inward and converge at the Cu^II coordination point to give rise to a spirometallocycle. Ligand L2 binds Cu^I cations to generate a supramolecule, diacetonitriledi‐μ₃‐iodido‐di‐μ₂‐iodido‐bis(4‐methyl‐{5‐[5‐methyl‐2‐(pyridin‐4‐ylcarbonyloxy)phenyl]‐1,3,4‐oxadiazol‐2‐yl}phenyl pyridine‐4‐carboxylate)tetracopper(I), [Cu₄I₄(CH₃CN)₂(C₂₈H₂₀N₄O₅)₂], (II). The asymmetric unit of (II) indicates that it contains two Cu^I atoms, one L2 ligand, one acetonitrile ligand and two iodide ligands. Both of the Cu^I atoms are four‐coordinated in an approximately tetrahedral environment. The molecule is centrosymmetric and the four I atoms and four Cu^I atoms form a rope‐ladder‐type [Cu₄I₄] unit. Discrete units are linked into one‐dimensional chains through π–π interactions.     

Pteridines. Part CXVIII

Our approach to achieve a partial synthesis of methanopterin ( 1 ) started from 6‐acetyl‐O⁴‐isopropyl‐7‐methylpterin ( 20 ) which was obtained either by condensation from 6‐isopropoxypyrimidine‐2,4,5‐triamine ( 19 ) and pentane‐2,3,4‐trione ( 6 ) or from 6‐isopropoxy‐5‐nitrosopyrimidine‐2,4‐diamine ( 21 ) and pentane‐2,4‐dione (=acetylacetone; 22 ) (Scheme 2). NaBH₄ reduction of 20 led to 6‐(1‐hydroxyethyl)‐O⁴‐isopropyl‐7‐methylpterin ( 23 ) which was converted into the corresponding 6‐(1‐chloroethyl) and 6‐(1‐bromoethyl) derivatives 24 and 25 . A series of nucleophilic displacement reactions in the side chain and at position 4 were performed as model reactions to give 26 – 29, 32 – 35 , and 39 – 41 . Hydrolysis of the substituents at C(4) led to the corresponding pterin derivatives 30, 31, 36 – 38 , and 42 . Analogously, 25 reacted with 1‐(4‐aminophenyl)‐1‐deoxy‐2,3: 4,5‐di‐O‐isopropylidene‐D ‐ribitol ( 43 ), prepared from N‐(4‐bromophenyl)benzamide ( 47 ) via 49 and 50 to give 1‐{4‐{{1‐[2‐amino‐7‐methyl‐4‐(1‐methylethoxy)pteridin‐6‐yl]ethyl}amino}phenyl}‐1‐deoxy‐D ‐ribitol ( 44 ) in 62% yield (Scheme 3). Acid cleavage of the isopropylidene groups at room temperature led to 45 and on boiling to 1‐{4‐{[1‐(2‐amino‐3,4‐dihydro‐7‐methyl‐4‐oxopteridin‐6‐yl)ethyl]amino}phenyl}‐1‐deoxy‐D ‐ribitol ( 46 ). The next step, however, attachment of the ribofuranosyl moiety with 55 or 56 to the terminal 1‐deoxy‐D ‐ribitol OH group could not been achieved. The second component, bis(4‐nitrobenzyl) 2‐{[(2‐cyanoethoxy)(diisopropylamino)phosphino]oxy}pentanedioate ( 61 ), to built‐up methanopterin ( 1 ) was synthesized from 2‐hydroxypentanedioic acid ( 59 ) and worked well in another model reaction on phosphitylation with N⁶‐benzoyl‐2′,3′‐O‐isopropylideneadenosine and oxidation to give 62 (Scheme 6).     

The gas-phase pyrolysis of alkyl nitrites. III. Isopropyl nitrite

The rate of decomposition of isopropyl nitrite (IPN) has been studied in a static system over the temperature range of 130–160°C. For low concentrations of IPN (1–5 × 10^?5M), but with a high total pressure of CF₄ (～0.9 atm) and small extents of reaction (～1%), the first-order rates of acetaldehyde (AcH) formation are a direct measure of reaction (1), since k₃ » k₂(NO): \documentclass{article}\usepackage{amssymb}\pagestyle{empty}\begin{document}$ {\rm IPN}\begin{array}{rcl} 1 \\ {\rightleftarrows} \\ 2 \\ \end{array}i - \Pr \mathop {\rm O}\limits^. + {\rm NO},i - \Pr \mathop {\rm O}\limits^. \stackrel{3}{\longrightarrow} {\rm AcH} + {\rm Me}. $\end{document} Addition of large amounts of NO (～0.9 atm) in place of CF₄ almost completely suppressed AcH formation. Addition of large amounts of isobutane – t-BuH – (～0.9 atm) in place of CF₄ at 160°C resulted in decreasing the AcH by 25%. Thus 25% of \documentclass{article}\pagestyle{empty}\begin{document}$ i - \Pr \mathop {\rm O}\limits^{\rm .} $\end{document} were trapped by the t-BuH (4): \documentclass{article}\pagestyle{empty}\begin{document}$ i - \Pr \mathop {\rm O}\limits^. + t - {\rm BuH} \stackrel{4}{\longrightarrow} i - \Pr {\rm OH} + (t - {\rm Bu}). $\end{document} The result of adding either NO or t-BuH shows that reaction (1) is the only route for the production of AcH. The rate constant for reaction (1) is given by k₁ = 10^{16.2±0.4–41.0±0.8}/θ sec^?1. Since (E₁ + RT) and ΔH°₁ are identical, within experimental error, both may be equated with D(i-PrO-NO) = 41.6 ± 0.8 kcal/mol and E₂ = 0 ± 0.8 kcal/mol. The thermochemistry leads to the result that \documentclass{article}\pagestyle{empty}\begin{document}$ \Delta H_f^\circ (i - {\rm Pr}\mathop {\rm O}\limits^{\rm .} ) = - 11.9 \pm 0.8{\rm kcal}/{\rm mol}. $\end{document} From ΔS°₁ and A₁, k₂ is calculated to be 10^10.5±0.4M^?1·sec^?1. From an independent observation that k₆/k₂ = 0.19 ± 0.03 independent of temperature we find E₆ = 0 ± 1 kcal/mol and k₆ = 10^9.8+0.4M^?;1·sec^?1: \documentclass{article}\pagestyle{empty}\begin{document}$ i - \Pr \mathop {\rm O}\limits^. + {\rm NO} \stackrel{6}{\longrightarrow} {\rm M}_2 {\rm K} + {\rm HNO}. $\end{document} In addition to AcH, acetone (M₂K) and isopropyl alcohol (IPA) are produced in approximately equal amounts. The rate of M₂K formation is markedly affected by the ratio S/V of different reaction vessels. It is concluded that the M₂K arises as the result of a heterogeneous elimination of HNO from IPN. In a spherical reaction vessel the first-order rate of M₂K formation is given by k₅ = 10^9.4–27.0/θ sec^?1: \documentclass{article}\pagestyle{empty}\begin{document}$ {\rm IPN} \stackrel{5}{\longrightarrow} {\rm M}_2 {\rm K} + {\rm HNO}. $\end{document} IPA is thought to arise via the hydrolysis of IPN, the water being formed from HNO. This elimination process explains previous erroneous results for IPN.     

Reaction of hydrogen atoms with dimethyldisulfide

Hydrogen atoms, generated by the mercury (³P₁) sensitization of H₂, were allowed to react with dimethyldisulfide in the temperature range of 25–155°C. The only retrievable product is methanethiol, formed in the primary metathetical reaction \documentclass{article}\pagestyle{empty}\begin{document}$ {\rm H} + {\rm CH}_3 {\rm SSCH}_3 {\rm CH}_3 {\rm SH} + {\rm CH}_3 {\rm S} $\end{document}. The intermediacy of thiyl radicals was clearly demonstrated in experiments carried out in the presence of ethylene where one of the major products detected was ethyl methyl sulfide, formed via CH₃S + C₂H₅ → CH₃SC₂H₅. The major fate of the CH₃S radical is recombination and disproportionation, and the yield of methanethiol formed via disproportionation contributes less than 5% to the total thiol yield. The rate coefficient of step 1, from competition with the reaction \documentclass{article}\pagestyle{empty}\begin{document}$ {\rm H} + {\rm C}_{\rm 2} {\rm H}_{\rm 4} {\rm C}_{\rm 2} {\rm H}_5 $\end{document}, is k₁ = (5.7 ± 1.2) × 10¹² exp[? (100 ± 100)/RT] cm³/mol sec.     

Methyl thiirane: Kinetic gas-phase titration of sulfur atoms in SX OY systems

The reaction SO + SO →l S + SO₂(2) was studied in the gas phase by using methyl thiirane as a titrant for sulfur atoms. By monitoring the C₃H₆ produced in the reaction \documentclass{article}\pagestyle{empty}\begin{document}$ {\rm S} + {\rm CH}_3\hbox{---} \overline {{\rm CH\hbox{---}CH}_2\hbox{---} {\rm S}} \to {\rm S}_2 + {\rm C}_3 {\rm H}_6 (7) $\end{document}, we determined that k₂ ? 3.5 × 10^?15 cm³/s at 298 K.     

The gas-phase pyrolysis of alkyl nitrites. II. s-butyl nitrite

The rate of decomposition of s-butyl nitrite (SBN) has been studied in the absence (130–160°C) and presence (160–200°C) of NO. Under the former conditions, for low concentrations of SBN (6 × 10^?5 ? 10^?4M) and small extents of reaction (～1.5%), the first-order homogeneous rates of acetaldehyde (AcH) formation are a direct measure of reaction (1) since k_3c » k₂(NO): . Unlike t-butyl nitrite (TBN), d(AcH)/dt is independent of added CF₄ (～0.9 atm). Thus k_3c is always » k₂ (NO) over this pressure range. Large amounts of NO (～0.9 atm) (130–160°C) completely suppress AcH formation. k₁ = 10^16.2–40.9/θ sec^?1. Since (E₁ + RT) and ΔH°₁ are identical, within experimental error, both may be equated with D(s-BuO-NO) = 41.5 ± 0.8 kcal/mol and E₂ = 0 ± 0.8 kcal/mol. The thermochemistry leads to the result ΔH°_f (s-\documentclass{article}\pagestyle{empty}\begin{document}${\rm Bu}\mathop {\rm O}\limits^{\rm .}$\end{document}) = ? 16.6 ± 0.8 kcal/mol. From ΔS°₁ and A₁, k₂ is calculated to be 10^10.4 M^?1 · sec^?1, identical to that for TBN. From an independent observation that k₆/k₂ = 0.26 ± 0.01 independent of temperature, \documentclass{article}\pagestyle{empty}\begin{document}${\rm s - Bu}\mathop {\rm O}\limits^{\rm .} + {\rm NO}\mathop \to \limits^{\rm 6} {\rm MEK} + {\rm HNO}$\end{document}, we find E₆ = 0 ± 1 kcal/mol and k₆ = 10^9.8M^?1 · sec^?1. Under the conditions first cited, methyl ethyl ketone (MEK) is also a product of the reaction, the rate of which becomes measurable at extents of conversion >2%. However, this rate is ～0.1 that of AcH formation. Although MEK formation is affected by the ratio S/V for different reaction vessels, in a spherical reaction vessel, this MEK arises as the result of an essentially homogeneous first-order 4-centre elimination of HNO. \documentclass{article}\pagestyle{empty}\begin{document}${\rm SBN}\mathop \to \limits^{\rm 5} {\rm MEK} + {\rm HNO}$\end{document}; k₅ = 10^12.8–35.8/θ sec^?1. Sec-butyl alcohol (SBA), formed at a rate comparable to MEK, is thought to arise via the hydrolysis of SBN, the water being formed from HNO. The rate of disappearance of SBN, that is, d(MEK + SBA + AcH)/dt, is given by k_global = 10^15.7–39.6/θ sec^?1. In NO (～1 atm) the rate of formation of MEK was about twice that in the absence of NO, whereas the SBA was greatly reduced. This reaction was also affected by the ratio S/V of different reaction vessels. It was again concluded that in a spherical reaction vessel, the rate of MEK formation was essentially homogeneous and first order. This rate is given by k_obs = 10^12.9–35.4/θ sec^?1, very similar to k₅. However, although it is clear that the rate of formation of MEK is doubled in the presence of NO, the value for k_obs makes it difficult to associate this extra MEK with the disproportionation of s-\documentclass{article}\pagestyle{empty}\begin{document}${\rm Bu}\mathop {\rm O}\limits^{\rm .}$\end{document} and NO: s-\documentclass{article}\pagestyle{empty}\begin{document}$s{\rm - Bu}\mathop {\rm O}\limits^{\rm .} + {\rm NO}\mathop \to \limits^{\rm 6} {\rm MEK} + {\rm HNO}$\end{document}. NO at temperatures of 130–160°C completely suppresses AcH formation. AcH reappears at higher temperatures (165–200°C), enabling k_3c to be determined. Ignoring reaction (6), d(AcH)/dt = k₁k₃ (SBN )/[k_3c + k₂(NO)]; k_3c = 10^14.8–15.3/θ sec^?1. Inclusion of reaction (6) into the mechanism makes very little difference to the result. Reaction (3c) is expected to be a pressure-dependent process.