Water-catalyzed O-H insertion/HI elimination reactions of isodihalomethanes (CH2X-I, where X = Cl, Br, I) with water and the dehalogenation of dihalomethanes in water-solvated environments

A combined experimental and theoretical investigation of the ultraviolet photolysis of CH2XI (where X = Cl, Br, I) dihalomethanes in water is presented. Ultraviolet photolysis of low concentrations of CH2XI (where X = Cl, Br, I) in water appears to lead to almost complete conversion into CH2(OH)2 and HX and HI products. Picosecond time-resolved resonance Raman (ps-TR3) spectroscopy experiments revealed that noticeable amounts of CH2X-I isodihalomethane intermediates were formed within several picoseconds after photolysis of the CH2XI parent compound in mixed aqueous solutions. The ps-TR3 experiments in mixed aqueous solutions revealed that the decay of the CH2X-I isodihalomethane intermediates become significantly shorter as the water concentration increases, indicating that the CH2X-I intermediates may be reacting with water. Ab initio calculations found that the CH2X-I intermediates are able to react relatively easily with water via a water-catalyzed O-H insertion/HI elimination reaction to produce CH2X(OH) and HI products, with the barrier for these reactions increasing as X changes from Cl to Br to I. The ab initio calculations also found that the CH2X(OH) product can undergo a water-catalyzed HX elimination reaction to make H2C=O and HX products, with the barrier to reaction decreasing as X changes from Cl to Br to I. The preceding two water-catalyzed reactions produce the HI and HX leaving groups observed experimentally, and the H2C=O product further reacts with water to make the other CH2(OH)2 product observed in the photochemistry experiments. This suggests that that the CH2X-I intermediates react with water to form the CH2(OH)2 and HI and HX products observed in the photochemistry experiments. Ultraviolet photolysis of CH2XI (where X = Cl, Br, I) at low concentrations in water-solvated environments appears to lead to efficient dehalogenation and release of two strong acid leaving groups. We very briefly discuss the potential influence of this photochemistry in water on the decomposition of polyhalomethanes and halomethanols in aqueous environments.     

Comparison of the dehalogenation of polyhalomethanes and production of strong acids in aqueous and salt (NaCl) water environments: Ultraviolet photolysis of CH(2)I(2)

The ultraviolet photolysis of CH(2)I(2) was studied in water and salt water solutions using photochemistry and picosecond time-resolved resonance Raman spectroscopy. Photolysis in both types of environments produces mainly CH(2)(OH)(2) and HI products. However, photolysis of CH(2)I(2) in salt water leads to the formation of different products/intermediates (CH(2)ICl and Cl(2) (-)) not observed in the absence of salt in aqueous solutions. The amount of CH(2)(OH)(2) and HI products appears to decrease after photolysis of CH(2)I(2) in salt water compared to pure water. We briefly discuss possible implications of these results for photolysis of CH(2)I(2) and other polyhalomethanes in sea water and other salt aqueous environments compared to nonsalt water solvated environments.     

Comparison of the dehalogenation of dihalomethanes (CH2XI, where X = Cl, Br, I) following ultraviolet photolysis in aqueous and NaCl saltwater environments

The ultraviolet photolysis of low concentrations of CH(2)XI (X = Cl, Br, I) were investigated in water and saltwater solutions by photochemistry and picosecond time-resolved resonance Raman spectroscopy. Photolysis in both kinds of solutions formed mostly CH(2)(OH)(2) and HI and HX products. However, photolysis of the CH(2)XI molecules in saltwater resulted in production of some CH(2)XCl products not observed in aqueous solutions without salt present. The appearance of these new products in saltwater solutions is accompanied by a decrease in the amount of CH(2)(OH)(2), HI, and HX products compared to photolysis in aqueous solutions without salt present. The possible implications for photolysis of CH(2)XI and other polyhalomethanes in seawater and other salt aqueous environments compared to nonsaltwater solvated environments is briefly discussed.     

Density functional theory investigation of the reaction of isodiiodomethane with acetylene: potential utility of isodiiodomethane for cyclopropenation reactions

We present density functional theory calculations for the reactions of CH2I-I and CH2I with acetylene (HC triple bond CH) to form a cyclopropene product. CH2I-I readily reacts with HC triple bond CH to form a cyclopropene product and an I2 leaving group via a rate-determining step barrier of approximately 3.9 kcal/mol (B3LYP/Sadlej-pVTZ). Calculations indicated that the CH2I radical reacts to form an iodopropenyl radical, which can close to a cyclopropene only with difficulty. Our results indicate that CH2I-I may act as an effective carbenoid to produce cyclopropenated products from alkynes.     

Ultraviolet photolysis of CH2I2 in methanol: O-H insertion and HI elimination reactions to form a dimethoxymethane product

Ultraviolet photolysis of low concentrations of CH2I2 in methanol solution found that CH2I2 is converted into dimethoxymethane and some H+ and I- products. Picosecond time-resolved resonance Raman (ps-TR3) experiments observed that the isodiiodomethane (CH2I-I) photoproduct decayed faster as the concentration of methanol increases, suggesting that isodiiodomethane is reacting with methanol. Ab initio calculations indicate isodiiodomethane is able to react with methanol via an O-H insertion/HI elimination to form an iodoether (ICH2-O-CH3) and HI products. The iodoether can then further react via another O-H insertion/HI elimination reaction to form the dimethoxymethane (CH3-O-CH2-O-CH3) observed in the photochemistry experiments. A reaction mechanism consistent with these experimental and theoretical observations is proposed.     

Direct observation of an isopolyhalomethane O-H insertion reaction with water: picosecond time-resolved resonance Raman (ps-TR3) study of the isobromoform reaction with water to produce a CHBr2OH product

Picosecond time-resolved resonance Raman (ps-TR3) spectroscopy was used to obtain the first definitive spectroscopic observation of an isopolyhalomethane O-H insertion reaction with water. The ps-TR3 spectra show that isobromoform is produced within several picoseconds after photolysis of CHBr3 and then reacts on the hundreds of picosecond time scale with water to produce a CHBr2OH reaction product. Photolysis of low concentrations of bromoform in aqueous solution resulted in noticeable formation of HBr strong acid. Ab initio calculations show that isobromoform can react with water to produce a CHBr2(OH) O-H insertion reaction product and a HBr leaving group. This is consistent with both the ps-TR3 experiments that observe the reaction of isobromoform with water to form a CHBr2(OH) product and photolysis experiments that show HBr acid formation. We briefly discuss the implications of these results for the phase dependent behavior of polyhalomethane photochemistry in the gas phase versus water solvated environments.     

Isodiiodomethane is the methylene transfer agent in cyclopropanation reactions with olefins using ultraviolet photolysis of diiodomethane in solutions: a density functional theory investigation of the reactions of isodiiodomethane, iodomethyl radical, and iodomethyl cation with ethylene.

We examine the chemical reactions of the isodiiodomethane (CH2I-I), .CH2I and CH2I(+) species with ethylene using density functional theory computations. The CH2I-I species readily reacts with ethylene to give the cyclopropane product and an I2 product via a one-step reaction with a barrier height of approximately 2.9 kcal/mol. However, the.CH2I and CH2I(+) species have much more difficult pathways (with larger potential barriers) to react with ethylene via a two-step reaction mechanism. Comparison of experimental results to our present calculation results indicates that the CH2I-I photoproduct species is most likely the methylene transfer agent for the cyclopropanation reaction of olefins via ultraviolet photoexcitation of diiodomethane.     

Density functional theory investigation of the reactions of isodihalomethanes (CH(2)X-X where X = Cl, Br, or I) with ethylene: substituent effects on the carbenoid behavior of the CH(2)X-X species

We investigated the chemical reactions of isodihalomethane (CH(2)X-X) and CH(2)X radical species (where X = Cl, Br, or I) with ethylene and the isomerization reactions of CH(2)X-X using density functional theory calculations. The CH(2)X-X species readily reacts with ethylene to give the cyclopropane product and an X(2) product via a one-step reaction with barrier heights of approximately 2.9 kcal/mol for CH(2)I-I, 6.8 kcal/mol for CH(2)Br-Br, and 8.9 kcal/mol for CH(2)Cl-Cl. The CH(2)X reactions with ethylene proceed via a two-step reaction mechanism to give a cyclopropane product and X atom product with much larger barriers to reaction. This suggests that photocyclopropanation reactions using ultraviolet excitation of dihalomethanes most likely occurs via the isodihalomethane species and not the CH(2)X species. The isomerization reactions of CH(2)X-X had barrier heights of approximately 14.4 kcal/mol for CH(2)I-I, 11.8 kcal/mol for CH(2)Br-Br, and 9.1 kcal/mol for CH(2)Cl-Cl. We compare our results for the CH(2)X-X carbenoids to results from previous calculations of the Simmons-Smith-type carbenoids (XCH(2)ZnX) and Li-type carbenoids (LiCH(2)X) and discuss their differences and similarities as methylene transfer agents.     

Water-catalyzed dehalogenation reactions of isobromoform and its reaction products

A combined experimental and theoretical study of the photochemistry of CHBr(3) in pure water and in acetonitrile/water mixed solvents is reported that elucidates the reactions and mechanisms responsible for the photochemical conversion of the halogen atoms in CHBr(3) into three bromide ions in water solution. Ultraviolet excitation at 240 nm of CHBr(3) (9 x 10(-)(5) M) in water resulted in almost complete conversion into 3HBr leaving groups and CO (major product) and HCOOH (minor product) molecules. Picosecond time-resolved resonance Raman (ps-TR(3)) experiments and ab initio calculations indicate that the water-catalyzed O-H insertion/HBr elimination reaction of isobromoform and subsequent reactions of its products are responsible for the production of the final products observed following ultraviolet excitation of CHBr(3) in water. These results have important implications for the phase-dependent behavior of polyhalomethane photochemistry and chemistry in water-solvated environments as compared to gas-phase reactions. The dissociation reaction of HBr into H(+) and Br(-) ions is the driving force for several O-H insertion and HBr elimination reactions and allows O-H and C-H bonds to be cleaved more easily than in the absence of water molecules. This water-catalysis by solvation of a leaving group and its dissociation into ions (e.g., H(+) and Br(-) in the examples investigated here) may occur for a wide range of chemical reactions taking place in water-solvated environments.     

Time-resolved resonance Raman and density functional theory investigation of iodocyclopropanation and addition reactions with alkenes after ultraviolet photolysis of iodoform

A time-resolved resonance Raman spectroscopic investigation is reported for the ultraviolet photolysis of CHI(3) in pure cyclohexane and mixed cyclohexane/cyclohexene solvents. The ICHI-I species is observed in pure cyclohexane solvent. Upon addition of cyclohexene, the ICHI-I species lifetime is reduced and new bands from an I(2):cyclohexene complex are observed. Density functional theory computations show that ICHI-I and CHI(2) species have similar barriers of reaction toward addition to the C=C of ethylene. The addition reaction of ICHI-I with ethylene results in formation of an iodocyclopropane and I(2) molecule while addition of.CHI(2) results in initial formation of a diiodopropyl radical intermediate. Ultraviolet photolysis of CHI(3) in the presence of cyclohexene is known to produce a reasonable yield of iodonorcarane product and some addition reaction products. We present a mechanism for the iodocyclopropanation reaction that is consistent with both experimental and theoretical characterization of reaction intermediates formed after ultraviolet photolysis of CHI(3). We briefly discuss the concentration dependence of the time-resolved resonance Raman spectra and photochemistry in relation to the competition between the reaction of the ICHI-I and CHI(2) species with the C=C bond of olefins.     

Water-catalyzed dehalogenation reactions of the isomer of CBr4 and its reaction products and a comparison to analogous reaction of the isomers of di-and trihalomethanes

A combined experimental and theoretical study of the UV photolysis of a typical tetrahalomethane, CBr4, in water and acetonitrile/water was performed. Ultraviolet photolysis of low concentrations of CBr4 in water mostly leads to the production of four HBr leaving groups and CO2. Picosecond time-resolved resonance Raman (Ps-TR3) experiments and ab initio calculations indicate that water-catalyzed O-H insertion/HBr elimination of the isomer of CBr4 and subsequent reactions of its products lead to the formation of these products. The UV photolyses of di-, tri-, and tetrahalomethanes at low concentrations in water-solvated environments are compared to one another. This comparison enables a general reaction scheme to be deduced that can account for the different products produced by UV photolysis of low concentrations of di-, tri-, and tetrahalomethanes in water. The fate of the (halo)formaldehyde intermediate in the chemical reaction mechanism is the key to determining how many strong acid leaving groups are produced and which carbon atom final product is likely formed by UV photolysis of a polyhalomethane at low concentrations in a water-solvated environment.     

A density functional theory investigation of the Simmons-Smith cyclopropanation reaction: examination of the insertion reaction of zinc into the C-I bond of CH(2)I(2) and subsequent cyclopropanation reactions.

The insertion reaction of zinc into the C-I bond of CH(2)I(2) and subsequent cyclopropanation reactions with CH(2)CH(2) have been investigated using B3LYP level density functional theory calculations. The Simmons-Smith cyclopropanation reaction of olefins does not proceed easily due to the relatively large barriers on the insertion and cyclopropanation pathways. The computed results indicate that the IZnCH(2)I molecule is the active reagent in the Simmons-Smith reaction. This is consistent with the IZnCH(2)I reactive species being generated from diiodomethane and a Zn-Cu couple as proposed by several other research groups. The Simmons-Smith IZnCH(2)I carbenoid and CH(2)I-I carbenoid cyclopropanation reactions with olefins are compared. The reactions of olefins with the radicals from the decomposition of the IZnCH(2)I and CH(2)I-I species were also compared. We found that the chemical reactivity of the carbenoid species is dependent on its electrophilic behavior, steric effects, the leaving group character and the mechanism of the cyclopropanation reactions.     

Photochemical investigation of Roussin's red salt esters: Fe2(mu-SR)2(NO)4

The photochemistry of various Roussin's red ester compounds of the general formula Fe(2)(SR)(2)(NO)(4), where R = CH(3), CH(2)CH(3), CH(2)C(6)H(5), CH(2)CH(2)OH, and CH(2)CH(2)SO(3)(-), were investigated. Continuous photolyses of these ester compounds in aerated solutions led to the release of NO with moderate quantum yields for the photodecomposition of the ester (Phi(RSE) = 0.02-0.13). Electrochemical studies using an NO electrode demonstrated that 4 mol of NO are generated for each mole of ester undergoing photodecomposition. Nanosecond flash photolysis studies of Fe(2)(SR)(2)(NO)(4) (where R = CH(2)CH(2)OH and CH(2)CH(2)SO(3)(-)) indicate that the initial photoreaction is the reversible dissociation of NO. In the absence of oxygen, the presumed intermediate, Fe(2)(SR)(2)(NO)(3), undergoes second-order reaction with NO to regenerate the parent cluster with a rate constant of k(NO) = 1.1 x 10(9) M(-1) s(-1) for R = CH(2)CH(2)OH. Under aerated conditions the intermediate reacts with oxygen to give permanent photochemistry.     

Reactions of radicals with hydrolyzed Bi(III) ions: a pulse radiolysis study

Radiolytic reduction of BiOClO4 in aqueous solutions leads to the formation of bismuth clusters and larger nanoparticles. The mechanisms of redox reactions of the polycationic Bi(III) species that exist in the solution were investigated with pulse radiolysis. The kinetic and spectral properties of the transients formed by the reaction of these species with the primary radicals from water radiolysis are reported. The single-electron reduction product, Bi9(OH)224+, absorbs at lambdamax = 273 nm, while the OH adduct, Bi9(OH)235+, has a broad absorption spectrum with a maximum at 280 nm and a shoulder at 420 nm. Several rate constants were measured: k (e-aq + Bi9(OH)225+) = 1.2 x 1010 M-1 s-1 and k (OH + Bi9(OH)225+) = 1.5 x 109 M-1 s-1. The reduced species, Bi9(OH)224+ further reacts with (CH3)2COH radicals, but not with CH2C(CH3)2OH radicals from t-butanol, to produce a doubly reduced polynuclear species. A few reactions of the reduction of the Bi salt in the presence of poly(acrylic acid) are also described. In the presence of the polymer, a metal-polymer complex is formed prior to the irradiation, and the reduction reactions are significantly slowed down.     

Structure and photochemistry of dicyanocobalt(III) tetraphenylporphyrin. Photochromic reaction caused by photodissociation of axial ligand

Chlorocobalt(III) tetraphenylporphyrin, (Cl)CoIIITPP, reacts with potassium cyanide in dichloromethane or benzene containing 18-crown-6 to give a green solution of [crown-K+][(CN)2CoIIITPP-]. The molecular structure of [crown-K+][(CN)2CoIIITPP-] is identified by X-ray crystallography. In methanol, (Cl)CoIIITPP plus KCN also gives a green solution of [(CN)2CoIIITPP-]. The green methanol solution containing 1.4 x 10(-4) M KCN turns orange by continuous photolysis with a 250-W mercury lamp for 5 min. The orange solution returns to green when it is kept in the dark for 5 min. The kinetic study suggests that [(CN)2CoIIITPP-] dissociates CN- by continuous photolysis, giving rise to the formation of the orange species, (CH3OH)(CN)CoIIITPP. The photoproduct, (CH3OH)(CN)CoIIITPP, regenerates the green species, [(CN)2CoIIITPP-], by reaction with CN-. The laser photolysis study of [(CN)2CoIIITPP-] in methanol demonstrates that photodissociation of CN- takes place within 20 ns after the 355-nm laser pulse, resulting in the formation of two transients, I (short-lived) and II (long-lived). The absorption spectra of both transients are similar to that of (CH3OH)(CN)CoIIITPP. These transients eventually return to [(CN)2CoIIITPP-]. The decay of species I follows first-order kinetics with a rate constant k. = 2 x 10(6) s-1, independent of the concentration of KCN. Species II is identified as (CH3OH)(CN)CoIIITPP, which is observed with the continuous photolysis of the solution. The laser photolysis of [crown-K+][(CN)2COIIITPP-] in dichloromethane gives the transient species, which goes back to the original complex according to first-order kinetics with a rate constant k = 5 x 10(6) s-1. [crown-K+][(CN)2CoIIITPP-] is concluded to photodissociate the axial CN- to form [crown-K+CN-][(CN)CoIIITPP] in which an oxygen atom of the crown moiety in [crown-K+CN-] is coordinated to the cobalt(III) atom of [(CN)CoIIITPP] at the axial position. The intracomplex reverse reaction of [crown-K+CN-][(CN)CoIIITPP] leads to the regeneration of [crown-K+][(CN)2CoIIITPP-]. The structure and the reaction of the transient species I observed for [(CN)2CoIIITPP-] in methanol are discussed on the basis of the laser photolysis studies of [crown-K+][(CN)2CoIIITPP-] in dichloromethane.     

Photolysis and OH-Initiated oxidation of glycolaldehyde under atmospheric conditions

The photolysis and OH-initiated oxidation of glycolaldehyde (HOCH(2)CHO), which are relevant atmospheric processes, have been investigated under different conditions using complementary methods in three different laboratories. The UV absorption cross sections of glycolaldehyde determined in two of the laboratories are in excellent agreement. The photolysis of glycolaldehyde in air has been investigated in a quartz cell with sunlamps and in the EUPHORE chamber irradiated by sunlight. The mean photolysis rate measured under solar radiation was (1.1 +/- 0.3) x 10(-5) s(-1) corresponding to a mean effective photolysis quantum yield of (1.3 +/- 0.3). The major products detected were HCHO and CO, whereas CH(3)OH was also observed with an initial yield around 10%. Evidence for OH production was found in both experiments using either OH scavenger or OH tracer species. Photolysis of glycolaldehyde was used as the OH source to measure the reaction rate constants of OH with a series of dienes by the relative method and to identify and quantify the oxidation products of the OH-initiated oxidation of 2-propanol. The different experiments suggest that OH is produced by the primary channel: HOCH(2)CHO + hnu --> OH + CH(2)CHO (1). The rate constant of the OH reaction with glycolaldehyde has been measured at 298 K using the relative method: k(glyc) = (1.2 +/- 0.3) x 10(-11) cm(3) molecule(-1) s(-1). The product study of the OH-initiated oxidation of glycolaldehyde in air has been performed using both a FEP bag and the EUPHORE chamber. HCHO was observed to be the major product with a primary yield of around 65%. Glyoxal (CHOCHO) was also observed in EUPHORE with a primary yield of (22 +/- 6)%. This yield corresponds to the branching ratio ( approximately 20%) of the H-atom abstraction channel from the CH(2) group in the OH + HOCH(2)CHO reaction, the major channel ( approximately 80%) being the H-atom abstraction from the carbonyl group. The data obtained in this work, especially the first determination of the photolysis rate of glycolaldehyde under atmospheric conditions, indicate that the OH reaction and photolysis can compete as tropospheric sinks for glycolaldehyde. Since glycolaldehyde is a significant oxidation product of isoprene whereas the photolysis of glycolaldehyde is a significant source of methanol, isoprene might contribute a few percent of the global budget of methanol.     

Photochemistry of cis,trans-[PtIV(en)(I)2(CH3COO)2] complex in aqueous solutions

Russian Chemical Bulletin - The photochemistry of aqueous solutions of the cis,trans-[PtIV(en)(I)2(CH3COO)2] complex (1) was studied by stationary photolysis, nanosecond laser flash photolysis and...     

Reactivity of iso-diiodomethane and iso-iodoform, isomers of CH2I2 and CHI3, toward the double bond of a variety of cycloalkenes

The metastable CH2I-I and CHI2-I isomers formed by UV photolysis of CH2I2 and CHI3 transfer methylene and iodomethylene groups, respectively, to a variety of cycloalkenes, leading to their cyclopropanation. More than a 100-fold increase of the reaction rate with increasing solvent polarity suggests a dipolar transition state. The fastest second-order rates observed were in CH3CN. However, CH2Cl2 will be the more appropriate reaction medium because the isomer thermal stability is greater in CH2Cl2 than in the more polar CH3CN.     

Photochemical cleavage and release of para-substituted phenols from alpha-keto amides

In aqueous media alpha-keto amides 4-YC6H4OCH2COCON(R)CH(R')CH3 (5a, R = Et, R' = H; 5b, R = iPr, R' = Me) with para-substituted phenolic substituents (Y = CN, CF3, H) undergo photocleavage and release of 4-YC6H4OH with formation of 5-methyleneoxazolidin-4-ones 7a,b. For both 5a,b quantum yields range from 0.2 to 0.3. The proposed mechanism involves transfer of hydrogen from an N-alkyl group to the keto oxygen to produce zwitterionic intermediates 8a-c that eliminate the para-substituted phenolate leaving groups. The resultant imminium ions H2C=C(OH)CON+(R)=C(R')CH3 9a,b cyclize intramolecularly to give 7a,b. The quantum yields for photoelimination decrease in CH3CN, CH2Cl2, or C6H6 due to competing cyclization of 8a,b to give oxazolidin-4-one products which retain the leaving group 4-YC6H4O- (Y = H, CN). A greater tendency to undergo cyclization in nonaqueous media is observed for the N,N-diethyl amides 5a than the N,N-diisopropyl amides 5b. With para electron releasing groups Y = CH3 and OCH3 quantum yields for photoelimination significantly decrease and 1,3-photorearrangment of the phenolic group is observed. The 1,3-rearrangement involves excited state ArO-C bond homolysis to give para-substituted phenoxyl radicals, which can be observed directly in laser flash photolysis experiments.     

13C, 18O, and D fractionation effects in the reactions of CH3OH isotopologues with Cl and OH radicals

A relative rate experiment is carried out for six isotopologues of methanol and their reactions with OH and Cl radicals. The reaction rates of CH2DOH, CHD2OH, CD3OH, (13)CH3OH, and CH3(18)OH with Cl and OH radicals are measured by long-path FTIR spectroscopy relative to CH3OH at 298 +/- 2 K and 1013 +/- 10 mbar. The OH source in the reaction chamber is photolysis of ozone to produce O((1)D) in the presence of a large excess of molecular hydrogen: O((1)D) + H2 --> OH + H. Cl is produced by the photolysis of Cl2. The FTIR spectra are fitted using a nonlinear least-squares spectral fitting method with measured high-resolution infrared spectra as references. The relative reaction rates defined as alpha = k(light)/k(heavy) are determined to be: k(OH + CH3OH)/k(OH + (13)CH3OH) = 1.031 +/- 0.020, k(OH + CH3OH)/k(OH + CH3(18)OH) = 1.017 +/- 0.012, k(OH + CH3OH)/k(OH + CH2DOH) = 1.119 +/- 0.045, k(OH + CH3OH)/k(OH + CHD2OH) = 1.326 +/- 0.021 and k(OH + CH3OH)/k(OH + CD3OH) = 2.566 +/- 0.042, k(Cl + CH3OH)/k(Cl + (13)CH3OH) = 1.055 +/- 0.016, k(Cl + CH3OH)/k(Cl + CH3(18)OH) = 1.025 +/- 0.022, k(Cl + CH3OH)/k(Cl + CH2DOH) = 1.162 +/- 0.022 and k(Cl + CH3OH)/k(Cl + CHD2OH) = 1.536 +/- 0.060, and k(Cl + CH3OH)/k(Cl + CD3OH) = 3.011 +/- 0.059. The errors represent 2sigma from the statistical analyses and do not include possible systematic errors. Ground-state potential energy hypersurfaces of the reactions were investigated in quantum chemistry calculations at the CCSD(T) level of theory with an extrapolated basis set. The (2)H, (13)C, and (18)O kinetic isotope effects of the OH and Cl reactions with CH3OH were further investigated using canonical variational transition state theory with small curvature tunneling and compared to experimental measurements as well as to those observed in CH4 and several other substituted methane species.