Rate constants for the addition of the 2-hydroxy-2-propyl radical to alkenes in solution

Absolute rate constants for the addition of the 2-hydroxy-2-propyl radical to 18 substituted alkenes (CH₂ = CXY) were determined at (296 ± 1) K in 2-propanol by time-resolved electronspin-resonance spectroscopy. With alkene substitution the rate constants vary by more than 6 orders of magnitude. For 3,3-dimethyl-but-1-ene the temperature dependence is given by log k/M^?1 · s^?1 = 6.4 minus;; 19.1/Θ where Θ = 2.303 RT in kJ/mol^?1. As shown by a good correlation with the alkene electron affinities, log k₂₉₆/M^?1 · s^?1 = 6.46 + 1.71 · EA/eV (r = 0.930), 2-hydroxy-2-propyl is a very nucleophilic radical, and its addition rates are highly governed by polar effects. © 1993 John Wiley & Sons, Inc.     

Rate constants for the reactions of the OH radical with the propyl and butyl nitrates and 1-nitrobutane at 298 ± 2 k

Using a relative rate method, rate constants for the gas-phase reactions of the OH radical with 1- and 2-propyl nitrate, 1- and 2-butyl nitrate and 1-nitrobutane have been determined in the presence of one atmosphere of air at 298 ± 2 K. Using rate constants for the reactions of the OH radical with propane and cyclohexane of 1.15 × 10^?12 and 7.49 × 10^?12 cm³ molecule^?1 s^?1, respectively, following rate constants (in units of 10^?12 cm³ molecule^?1 s^?1) were obtained: 1-propyl nitrate, 0.62; 2-propyl nitrate, 0.41; 1-butyl nitrate, 1.78; 2-butyl nitrate, 0.93; and 1-nitrobutane, 1.35. These rate constants are compared and discussed with the literature data.     

Quantitative rate constants for radical reactions in the nanopores of cotton

The understanding of radical reactions in nanostructured materials is important for developing new synthetic procedures and controlling degradation reactions. To develop this area, an easy method for measuring quantitative rate constants of some radical reactions in nanostructures is required. A simple method for measuring the rate constant of dye bleaching, kdye, by organic radicals in such materials is introduced, involving the measurement of microsecond bleaching kinetics by diffuse reflectance spectroscopy, following laser flash creation of the radicals. Using wet and dry cotton as model substrates, we obtained kdye of 2-hydroxy-2-propyl and 1-hydroxy-1-cyclohexyl radicals with reactive red 3 and reactive orange 4 and compared them to solution-phase values. Surprisingly, the reactions in cotton follow simple liquid-phase kinetics and are diffusion-controlled. A cage effect in cotton is also found.     

光解苯半醌和2-羟基-2-丙基自由基的CIDEP谱

用高时间分辨ＥＳＲ波谱仪测量了光解苯半醌和２－羟基－２－丙基自由基的ＣＩＤＥＰ谱,苯半醌自由基的ＣＩＤＥＰ属ＴＭ机理,实验研究了微波功率,溶液浓度对苯半醌自由基的ＣＩＤＥＰ谱时间演化的影响,２－羟基－２－丙基自由基的ＣＩＤＥＰ属ＲＰＭ机理,实验研究了自旋极化的生成环境。     

A direct arylation-oxidation route to 3-arylisoindolinone inhibitors of MDM2-p53 interaction

A route to the MDM2-p53 inhibitor isoindolinone pharmacophore from a pre-formed phthalimide is detailed. The route involves treatment of 3-hydroxy-2-(n-propyl)isoindolinone with a substituted benzene in the presence of triflic acid. The resulting 3-aryl-2-(n-propyl)isoindolinones are then oxidized to the corresponding 3-hydroxy-3-aryl-2-(n-propyl) isoindolinones by treatment with 2,2’-bipyridinium chlorochromate. The benzylic oxidation represents a rather rare oxochromium (VI)-mediated reaction in which a selective C-H to C-OH transformation occurs.     

Properties of an amphoteric cellulose derivative containing anionic carboxymethyl and cationic 2-hydroxy-3-(trimethylammonio) propyl substituents

An amphoteric cellulose derivative, O-carboxymethyl-O-2-hydroxy-3-(trimethylammonio) propylcellulose (CM-HTMAPC), was prepared by the etherification of O-carboxymethylcellulose (CMC) with (3-chloro-2-hydroxy-n-propyl)-trimethylammonium chloride in a NaOH solution. Apparent molecular sizes of the amphoteric cellulose derivative in aqueous solutions of different NaCl concentrations under various pH conditions were investigated by gel permeation chromatography (GPC), and results were evaluated in terms of inter- and intramolecular ionic interactions. Relation between GPC and viscosity results was also discussed. A titration method to determine the apparent acidic dissociation constants of carboxymethyl substituents was developed and the effect of cationic substituents on apparent acidic dissociation constants was examined. ©1995 John Wiley & Sons, Inc.     

Synthesis and Characterization of Oxybis(Diacetoxyborane) Derivatives of Bifunctional Tridentate Aldimines

The reactions of oxybis(diacetoxyborane) with the aldimines, N-(2-hydroxyethyl) salicylaldimine N-(2-hydroxy-1-propyl) salicylaldimine, N-(3-hydroxy-1-propyl) salicylaldimine, N-(o-hydroxyphenyl) salicylaldimine. N-(m-hydroxyphenyl) salicylaldimine, N(2-hydroxyethyl)-2-hydroxy-1-naphthaldimine and N(2-hydroxy-1-propyl) 2-hydroxy-1-naphthaldimine have been carried out in 1: 1 and 1: 2 molar ratios. All the compounds except those derived from N-(3-hydroxy-1-propyl) salicylaldimine have been found to be sparingly soluble in benzene and nonelectrolytes in anhydrous DMF. The newly synthesized derivatives have been characterized by elemental analysis, molecular weight determinations and infrared, proton magnetic resonance, ultraviolet, visible and ¹¹B nuclear magnetic resonance spectral studies.     

Synthesis and Properties of 7-Acetyl-8-aryl-9-cyano-3-hydroxy-6-methyl-3,4-dihydro-2H,8H-pyrido[2,1-<Emphasis Type="Italic">b</Emphasis>][1,3]thiazines

7-Acetyl-8-aryl-2-(1-chloro-2-hydroxy-3-propyl)thio-9-cyano-6-methyl-1,4-dihydropyridines were obtained by treatment of 1,4-dihydropyridine-2(3H)-thiones with epichlorohydrin in the presence of sodium bicarbonate. When treated with NaOMe, these compounds are readily intramolecularly alkylated with formation of 7-acetyl-8-aryl-3-hydroxy-9-cyano-6-methyl-3,4-dihydro-2H,8H-pyrido[2,1-b]-[1,3]thiazines. We have studied amination of 2-(1-chloro-2-hydroxy-3-propyl)thio-1,4-dihydropyridines and acylation of 3-hydroxy-3,4-dihydro-2H,8H-pyrido[2,1-b][1,3]thiazines. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1394–1399, September, 2005.     

Organoboron compounds: CDV. Bromination of 2-isopropyl-2-boraadamantane

Bromination of 2-isopropyl-2-boraadamantane in CH₂Cl₂ proceeds simultaneously by both radical and electrophilic mechanisms. The first involves elimination of HBr and formation of 2-(2-bromo-2-propyl)-2-boraadamantane; this rearranges, under the action of nucleophilic reagents, to a derivative of 4-borahomoadamantane, which converts, on oxidation, to 3α-hydroxy-7α-(2-hydroxy-2-propyl)bicyclo[3.3.1]-nonane. The second direction includes cleavage of a BC(isopropyl) bond with formation of i-PrBr and 2-bromo-2-boraadamantane, oxidation of which leads to 3α, 7α-dihydroxybicyclo[3.3.1]nonane. In the presence of H₂O, a solvated Br⁺ also takes part in the bromination, which results in formation of hydroxy (3-noradamantyl)isopropylborane, which is oxidized to 3-noradamantanol. Depending on the reaction conditions one of the three possible directions may predominate.     

Reactions of hydrated electron with various radicals: spin factor in diffusion-controlled reactions

The reactions of hydrated electron (eaq-) with various radicals have been studied in pulse radiolysis experiments. These radicals are hydroxyl radical (*OH), sulfite radical anion (*SO3-), carbonate radical anion (CO3*-), carbon dioxide radical anion (*CO2-), azidyl radical (*N3), dibromine radical anion (Br2*-), diiodine radical anion (I2*-), 2-hydroxy-2-propyl radical (*C(CH3)2OH), 2-hydroxy-2-methyl-1-propyl radical ((*CH2)(CH3)2COH), hydroxycyclohexadienyl radical (*C6H6OH), phenoxyl radical (C6H5O*), p-methylphenoxyl radical (p-(H3C)C6H4O*), p-benzosemiquinone radical anion (p-OC6H4O*-), and phenylthiyl radical (C6H5S*). The kinetics of eaq- was followed in the presence of the counter radicals in transient optical absorption measurements. The rate constants of the eaq- reactions with radicals have been determined over a temperature range of 5-75 degrees C from the kinetic analysis of systems of multiple second-order reactions. The observed high rate constants for all the eaq- + radical reactions have been analyzed with the Smoluchowski equation. This analysis suggests that many of the eaq- + radical reactions are diffusion-controlled with a spin factor of 1/4, while other reactions with *OH, *N3, Br2*-, I2*-, and C6H5S* have spin factors significantly larger than 1/4. Spin dynamics for the eaq-/radical pairs is discussed to explain the different spin factors. The reactions with *OH, *N3, Br2*-, and I2*- have also been found to have apparent activation energies less than that for diffusion control, and it is suggested that the spin factors for these reactions decrease with increasing temperature. Such a decrease in spin factor may reflect a changing competition between spin relaxation/conversion and diffusive escape from the radical pairs.     

Organic free radicals in superheated water studied by muon spin spectroscopy

There is a pressing need to identify and monitor reaction intermediates in water at high temperatures and pressures, but conventional techniques have limited capability for studying transient free radicals under such challenging conditions. Apparatus has now been developed to permit muon avoided-level crossing spectroscopy (muLCR) of organic free radicals in superheated water. The combination of muLCR with transverse-field muon spin rotation (TF-muSR) provides the means to identify and characterize free radicals via their nuclear hyperfine coupling constants. Because the radicals are derived from the addition of muonium (Mu = mu+ e-) to unsaturated compounds, the ensuing muoniated free radicals correspond to conventional organic free radicals but with a muon spin label substituted for one of the protons. Muon spin spectroscopy is the only technique presently being used to characterize transient free radicals under hydrothermal conditions in an unambiguous manner, free from interference from other reaction intermediates. This paper demonstrates how muoniated radicals can be used to monitor the species present in hydrothermal systems, and examples are presented from two classes of reaction: dehydration of alcohols and enolization of ketones. Spectra are displayed and hyperfine constants reported for muoniated forms of the following free radicals in superheated water (typically 350 degrees C at 250 bar): 2-propyl, 2-methyl-2-propyl (tert-butyl), and 2-hydroxy-2-propyl. The latter radical is the product of muonium addition to both the keto and the enol forms of acetone, but different isotopomers are produced according to which reaction channel is dominant. This should prove invaluable in future studies of the role of enols in combustion.     

Synthesis and molecular structure of the methyl ester of 3-bromo-2-(2-hydroxy-2-propyl)-7-oxo-7H-selenolo[2,3-<Emphasis Type="Italic">f</Emphasis>]chromene-8-carboxylic acid

A two-stage method has been developed for the synthesis of the methyl ester of 3-bromo-2-(2-hydroxy-2-propyl)-7-oxo-7H-selenolo[2,3-f]chromene-8-carboxylic acid – a new example of a class of selenophene-containing polycyclic heterocycles. The molecular structure was confirmed by X-ray crystallography.     

A kinetic study of the reactions of 2-propyl radicals in the liquid phase in the presence and absence of oxygen

2-Propyl radicals have been generated from the photolysis of solutions of 2,2-azopropane and 2,4-dimethyl-3-pentanone in decane in a glass and a metal cell. The time course of their reactions in the presence and absence of oxygen has been monitored between 323 and 373 K. The primary process involves the formation of solvent-caged radical pairs, two 2-propyl radicals and a 2-propyl and a 2-methylpropanoyl radical from the azo and ketone precursors, respectively. Subsequently these radicals are partitioned between cage escape and dimerization and disproportionation within the cage. In oxygenated solution the free 2-propyl radicals are effectively trapped as 2-propylperoxyl radicals. However, oxygen does not react with the solvent-caged radicals. This leads to a major difference in the hydrocarbon products from the two precursors. 2,2′-Azopropane gives propane, propene, and 2,3-dimethylbutane from the start of the reaction whereas the ketone only gives propene. Following the depletion of oxygen or in the absence of oxygen, both precursors behave analogously and give all three hydrocarbons. The 2-propylperoxyl radicals undergo self-reaction and hydrogen abstraction from the solvent to give 2-propanol, propanone, and 2-propyl hydroperoxide and, under conditions of low oxygen concentration, by reaction with 2-propyl radicals they give 2,2′-dipropylperoxide. Although the two cells lead to different overall rates of reaction, the relative rates and product distributions are unaffected by the cell design. A unified mechanism is described and the known and best estimates of rate constants for the individual steps are used to simulate the time dependence of the product yields from the photolysis of both precursors. © 1996 John Wiley & Sons, Inc.     

Functional polymers. XVI. Synthesis and polymerization of 2(2-hydroxy-5-isopropenylphenyl)-2H-benzotriazole and a new synthesis of 2(2-hydroxy-5-vinylphenyl)2H-benzotriazole

2(2-Hydroxy-5-isopropenylphenyl)2H-benzotriazole was synthesized in 40% overall yield starting from o-nitroaniline. Diazotization in aqueous hydrochloric acid gave o-nitrophenyl diazonium chloride which was condensed with p-hydroxyacetophenone; the azo compound was reduced to 2(2-hydroxy-5-acetylphenyl) 2H-benzotriazole with zinc powder in sodium hydroxide solution and the 2-hydroxy group of the compound was acetylated. Treatment of the acetyl compound with methyl Grignard reagent resulted in the methylation of the 5-acetyl group to 2[2-acetoxy-5(2-hydroxy-2-propyl)phenyl]2H-benzotriazole which was then dehydrated with potassium hydrogen sulfate to the desired 2(2-hydroxy-5-isopropenylphenyl)2H-benzotriazole. This monomer did not homopolymerize, but was copolymerized readily with styrene, methyl methacrylate, and n-butyl acrylate with azobisisobutyronitrile as the initiator. 2(2-Acetoxy-5-acetylphenyl)2H-benzotriazole was also reduced with sodium borohydride to form 2[2-acetoxy-5-(1-hydroxyethyl)phenyl]2H-benzotriazole which was dehydrated and hydrolyzed to the known 2(2-hydroxy-5-vinylphenyl)-2H-benzotriazole. This route provides a novel and simpler synthesis of 2(2-hydroxy-5-vinylphenyl)2H-benzotriazole.     

Catalytic hydrogenation of persubstituted <Emphasis Type="Italic">p</Emphasis>-nitrosophenols

Catalytic hydrogenation of dialkyl 2-hydroxy-4,6-dimethyl-5-nitrosobenzene-1,3-dicarboxylates over Pd/C gave the corresponding previously unknown dialkyl 5-amino-2-hydroxy-4,6-dimethylbenzene-1,3-dicarboxylates. The first-order rate constants for the hydrogenation process were found to be linearly related to steric constants of the alkyl groups.     

PHOTOCHEMICAL AND FREE RADICAL INITIATED REACTIONS OF1,3-DIMETHYLTHYMINE WITH ISOPROPANOL

Abstract— A photochemically induced reaction of 1 ,3-dimethylthymine (DMT) with isopropanol leads to the formation of four alcohol adducts. The products have been identified as the cis and trans isomers of 5 ,6-dihydro-1,3-dimethyll-6-(2-hydroxy-2-propyl) thymine (I and II), 2.4-diaza-8-hydroxy-2.4,6.8-tetramethylbicyclo[4.2.0]octan-1,3-dione (III), and 5 ,6-dihydro-1,3-dimethyl-6-(2-oxo-l-propyl)-thymine (IV). An acetone photosensitized reaction of DMT with isopropanol gives the same products in a similar relative yield distribution. In both of these reactions, cyclobutane dimers of DMT are produced as well. Free radical reactions of 2-hydroxyisopropyl radicals with DMT, initiated by decomposition of di- t -butyl peroxide, leads to formation of only one of the cis and trans isomers described above. along with 1 ,3-dimethyl-5-(2-hydroxy-2-methyl-1-propyl)uracil (V).     

5-Hydroxy-2,3-dihydrobenzofuran-derived polyfunctional antioxidants 2. Synthesis of 2-dodecylselenomethyl-5-hydroxy-2,3-dihydrobenzofurans and their antioxidant profile <Emphasis Type="Italic">versus</Emphasis> 2-dodecylthiomethyl-substituted analogs

A number of 2-dodecylselenomethyl-5-hydroxy-2,3-dihydrobenzofurans were synthesized from the corresponding 5-alkoxy-2-iodomethyl-substituted derivatives. The rate constants of the reaction with peroxide radicals and stoichiometric coefficients of inhibition were measured for the synthesized compounds and their 2-dodecylthiomethyl substituted analogs in the model reaction of initiated styrene oxidation. The dissociation energies of O–H bond were also calculated. 2-Dodecylselenomethyl-5-hydroxy-2,3-dihydrobenzofurans exceed their sulfurcontaining analogs and tocopherols by antioxidant activity in the thermal autooxidation of methyl oleate by a factor of 9–14 and 19–20, respectively.     

Kinetics of the gas-phase reactions of OH radicals with alkyl nitrates at 299 ± 2 K

Relative rate constants for the gas-phase reactions of OH radicals with a series of alkyl nitrates have been determined at 299 ± 2 K, using methyl nitrite photolysis in air as a source of OH radicals. Using a rate constant for the reaction of OH radicals with cyclohexane of 7.57 × 10^?12 cm³/molec·s, the rate constants obtained are (× 10¹² cm³/molec·s): 2-propyl nitrate, 0.18 ± 0.05; 1-butyl nitrate, 1.42 ± 0.11; 2-butyl nitrate, 0.69 ± 0.10; 2-pentyl nitrate, 1.87 ± 0.12; 3-pentyl nitrate, 1.13 ± 0.20; 2-hexyl nitrate, 3.19 ± 0.16; 3-hexyl nitrate, 2.72 ± 0.22; 3-heptyl nitrate, 3.72 ± 0.43; and 3-octyl nitrate, 3.91 ± 0.80. These rate constants, which are the first reported for the alkyl nitrates, are significantly lower than those for the parent alkanes, and a formula, based on the numbers of the various types of C? H bonds in the alkyl nitrates, is derived for rate constant estimation purposes.     

Chemistry of sulfonyl isocyanates and sulfonyl isothiocyanates. IX. Routes to substituted oxazolidin-2-ones and oxazolidine-2-thiones

4-Chlorobenzenesulfonyl isocyanate (I) reacted with 2-chloroethanol and 1-chloro-2-propanol to give, respectively, 2-chloroethyl 4-chlorobenzenesulfonyl carbamate (III) and 1-chloro-2-propyl 4-chlorobenzenesulfonyl carbamate (VI). The carbamates III and VI cyclized under the influence of pyridine to afford, respectively, 3-(4-chlorobenzenesulfonyl)oxazolidin-2-one (IV) and 3-(4-chlorobenzenesulfonyl)-5-methyloxazolidin-2-one (VII). The oxazolidin-2-ones were stable toward hydrochloric acid but hydrolyzed in 2M sodium hydroxide solution to N-(2-hydroxyethyl)-4-chlorobenzenesulfonamide (V) and N-(2-hydroxy-1-propyl)-4-chlorobenzene-sulfonamide (VIII), respectively. 4-Toluenesulfonyl isothiocyanate (II) reacted with 2-chloroethanol to give 2-chloroethyl 4-chlorobenzenesulfonyl thiocarbamate (IX), which was converted by pyridine to 3-(4-toluenesulfonyl)oxazolidine-2-thione (X).     

A relative rate study of the reaction of Cl atoms with a series of alkyl nitrates and nitro alkanes in air at 295 ± 2 K

The relative rate technique has been used to measure rate constants for the reaction of chlorine atoms with nitro methane, nitro ethane, nitro propane, nitro butane, nitro pentane, ethyl nitrate, isopropyl nitrate, n-propyl nitrate, 2-pentyl nitrate, and 2-heptyl nitrate. Decay rates of these organic species were measured relative to one or more of the following reference compounds; n-butane, ethane, chloroethane, and methane. Using rate constants of 2.25 × 10^?10 5.7 × 10^?11, 8.04 × 10^?12, and 1.0 × 10^?13 cm³ molecule^?1 s^?1 for the reaction of Cl atoms with n-butane, ethane, chloroethane, and methane, respectively, the following rate constants were derived, in units of cm³ molecule^?1 s^?1: nitro methane, <7 × 10^?15; nitro ethane, (2.05 ± 0.14) × 10^?13; nitro propane, (1.13 ± 0.05) × 10^?11; nitro butane, (5.13 ± 0.68) × 10^?11; nitro pentane, (1.40 ± 0.14) × 10^?10; ethyl nitrate, (3.70 ± 0.24) × 10^?12; n-propyl nitrate, (2.15 ± 0.13) × 10^?11; i-propyl nitrate, (3.94 ± 0.48) × 10^?12; 2-pentyl nitrate, (1.00 ± 0.06) × 10^?10; and 2-heptyl nitrate, (2.84 ± 0.50) × 10^?10. Quoted errors represent 2σ and do not include possible systematic errors due to errors in the reference rate constants. Experiments were performed at 295 ± 2 K and atmospheric pressure (?740 torr) of synthetic air. The results are discussed with respect to the previous literature data and to the modeling of these compounds in the atmosphere.