The efficient liquid‐phase oxidation of aromatic hydrocarbons by molecular oxygen in the presence of MnCO3

BACKGROUND: The liquid‐phase catalytic oxidation of aromatic hydrocarbons by molecular oxygen is a commercially important process. We consider the MnCO₃‐promoted oxidation of toluene to produce benzaldehyde and benzoic acid. In this investigation, toluene was oxidized with 25.0% conversion and 80.8% selectivity with respect to benzoic acid in the presence of MnCO₃ under 1.0 MPa of oxygen at 190 °C for 2 h. RESULTS: Moreover, the oxidation of other aromatic hydrocarbons, such as ethylbenzene, p‐xylene, m‐xylene, o‐xylene, and p‐chlorotoluene, were also efficiently promoted by MnCO₃. CONCLUSION: It is concluded that an efficient oxidation of aromatic hydrocarbons can be achieved in the presence of MnCO₃ under solvent‐free conditions. The catalytically active species are high‐valence Mn generated via the action of MnCO₃ with oxygen. Copyright © 2007 Society of Chemical Industry     

Solvent‐free diazotization–azidation of aryl amine using a polymer‐supported azide ion

Crosslinked poly (4‐vinylpyridine)‐supported azide ion was used as an effective azidating agent for deazodination of stable arenediazonium salts under solvent‐free conditions in high yields. The diazotization of aromatic amines was prepared by grinding the combination of an aromatic amine, sodium nitrite (NaNO₂), p‐toluene sulfonic acid (p‐TsOH), and 0.2 mL H₂O in a mortar. Grinding was continued for deazodination–azidation of the obtained relatively stable diazonium salts, with addition of crosslinked poly (4‐vinylpyridine) supported azide ion to obtain the corresponding aryl azides. The spent polymeric reagents can usually be removed and regenerated. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Synthesis and characterization of novel aromatic polyamides derived from 2,2′‐bis(p‐phenoxyphenyl)‐4, 4′‐diaminodiphenyl ether

BACKGROUND: Wholly aromatic polyamides (aramids) are high‐performance polymeric materials with outstanding heat resistance and excellent chemical stabilities due to chain stiffness and intermolecular hydrogen bonding of amide groups. Synthesis of structurally well‐designed monomers is an effective strategy to prepare modified forms of these aramids to overcome lack of organo‐solubility and processability limitations. RESULTS: A novel class of wholly aromatic polyamides was prepared from a new diamine, namely 2,2′‐bis(p‐phenoxyphenyl)‐4,4′‐diaminodiphenyl ether (PPAPE), and two simple aromatic dicarboxylic acids. Two reference polyamides were also prepared by reacting 4,4′‐diaminodiphenyl ether with the same comonomers under similar conditions. M?_w and M?_n of the resultant polymers were 8.0 × 10⁴ and 5.5 × 10⁴ g mol^?1, respectively. Polymers resulting from PPAPE exhibited a nearly amorphous nature. These polyamides exhibited excellent organo‐solubility in a variety of polar solvents and possessed glass transition temperatures up to 200 °C. The 10% weight loss temperatures of these polymers were found to be up to 500 °C under a nitrogen atmosphere. The polymers obtained from PPAPE could be cast into transparent and flexible films from N,N‐dimethylacetamide solution. CONCLUSION: The results obtained show that the new PPAPE diamine can be considered as a good monomer to enhance the processability of its resultant aromatic polyamides while maintaining their high thermal stability. The observed characteristics of the polyamides obtained make them promising high‐performance polymeric materials. Copyright © 2009 Society of Chemical Industry     

Surfactant‐Stabilized Aqueous Iridium(0) Colloidal Suspension: An Efficient Reusable Catalyst for Hydrogenation of Arenes in Biphasic Media

Aqueous suspensions of iridium nanoparticles produced by the chemical reduction of IrCl₃ assisted by sonication, in the presence of N,N‐dimethyl‐N‐cetyl‐N‐(2‐hydroxyethyl)ammonium chloride salt as surfactant, have shown an efficient activity for the catalytic hydrogenation of various aromatic derivatives in biphasic media under mild conditions. These nanocatalysts can be reused for further runs with a total conservation of activity and provided significant catalytic lifetime for anisole hydrogenation in pure water with 3000 total turn‐over (TTO).     

Eine neue,breit anwendbare Synthese für aromatische Aldehyde

Diformamide ( 1 ) reacts with activated aromatic compounds like toluene, anisole, m‐xylene, 1,2‐dimethoxybenzene in the presence of AlCl₃ to give N‐(diarylmethyl)‐formamides 2a—d , the corresponding aromatic aldehydes 3—6 are formed as by‐products in low yields. From N,N‐dimethylaniline and 1 /AlCl₃ the triphenylmethane derivative 7 can be obtained. The reaction of anisole with N‐methyl‐diformamide ( 9 ) affords the formamide 10 . The mixture of formamide, P₄O₁₀ and AlCl₃ reveals to be a reagent which is capable to formylate toluene and anisole, resp. Triformamide ( 14 )/AlCl₃ is an effective formylating system which allows the preparation of aromatic aldehydes (e.g. 3,4,17—32 ) from the corresponding aromatic hydrocarbons. Aluminiumchloride can be replaced by borontrichloride. The yields of the formylation reactions depend strongly from the reaction conditions (molar ratio: aromatic hydrocarbon/AlCl₃/ 14 ; solvent, reaction temperature). The scope of the reaction covers nearly complete those of the Gattermann‐Koch‐, Gattermann‐ and Vilsmeier—Haack‐reaction.     

Synthesis and characterization of first‐ and second‐generation polyamide pyridylimine nickel dihalide metallodendrimers and their uses as catalysts for ethylene polymerization

First‐ and second‐generation pyridylimine‐terminated dendrimeric ligands were prepared by the reaction of the corresponding amine‐terminated aromatic polyamide dendrimers with 2‐acetylpyridine. The pyridylimine terminal groups were used as bidentate N,N ligands of nickel halide to prepare the corresponding first‐generation and second‐generation nickel dihalide metallodendrimers C1 and C2 , respectively. The synthesized dendrimers and metallodendrimers were characterized by elemental and spectral analyses. C1 and C2 were evaluated as catalyst precursors for ethylene oligomerization after being activated with methylaluminoxane (MAO) and diethylaluminum chloride (Et₂AlCl) under 1 atm and 5 atm pressure of ethylene. In both cases, the use of 1 atm or 5 atm pressure of ethylene and a 1500:1 Al:Ni molar ratio for C1 and C2 resulted in high catalytic activities toward ethylene polymerization. Upon activation with MAO and Et₂AlCl, C1 exhibited promising activities toward ethylene polymerization and produced linear chain structures that were associated with high density polyethylene. In contrast, C2 produced a polymer with the branching nature of low density polyethylene under similar conditions. © 2014 Society of Chemical Industry     

Palladium(II)‐Catalyzed Direct ortho‐C?H Acylation of Anilides by Oxidative Cross‐Coupling with Aldehydes using tert‐Butyl Hydroperoxide as Oxidant

An efficient palladium‐catalyzed C H acylation with aldehydes using tert‐butyl hydroperoxide (TBHP) transforms various anilides into synthetically useful 2‐aminobenzophenone derivatives under mild conditions (40 °C, 3 h). The acylation reaction exhibits excellent regioselectivity and functional group tolerance, and simple aromatic aldehydes, functionalized aliphatic aldehydes and heteroaromatic aldehydes are effective coupling partners. The acylation reaction is probably initiated by a rate‐limiting electrophilic C H cyclopalladation (k_H/k_D=3.6; ρ⁺=−0.74) to form an arylpalladium complex, followed by acyl radical functionalization.     

Composition,thermal properties,and biodegradability of a new biodegradable aliphatic/aromatic copolyester

A series of new aliphatic/aromatic copolyesters [poly(hexylene terephthalate‐co‐hexylene adipate) (PHTA)] were synthesized on the bases of 1,6‐hexanediol, adipic acid, and dimethyl terephthalate and characterized by gel permeation chromatography, ¹H‐NMR, wide‐angle X‐ray diffraction (WAXD), differential scanning calorimetry (DSC), and compost testing. ¹H‐NMR results show that the compositions of the copolyesters were in accordance with the feed molar ratios. The WAXD patterns indicated that the crystal structures of the PHTA copolyesters were determined by the dominant crystal units, and the copolyesters became less crystallizable, even amorphous, with increasing comonomer content. The DSC curves showed that the glass‐transition temperatures (T_g′s) of the PHTA copolyesters decreased linearly, and both the melting temperature (T_m) and heat of fusion decreased first and then increased with increasing hexylene adipate unit content. Under compost conditions, PHTA copolyesters with less than 60 mol % aromatic units were biodegradable. Particularly, compared with the copolyester poly(butylene terephthalate‐co‐butylene adipate), the PHTA copolyester with the same aliphatic/aromatic composition possessed a lower T_g and T_m and better biodegradability. Additionally, the biodegradability of the copolyesters could be predicted by the number‐average sequence length of aromatic units, T_g, and the temperature difference between T_m and the temperature at which biodegradation took place. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Partially aromatic polyamides based on tetraphenylthiophene diamine: Synthesis and characterization

Tetraphenylthiophene diamine (TPTDA) was prepared through a modified three‐step route to achieve an improved overall yield. TPTDA reacted with succinic, adipic, suberic, sebasic, and fumaric acids via the Yamazaki phosphorylation method to yield novel partially aromatic polyamides (TPT series). A counterpart polyamide series based on p‐phenylene diamine (Ph series) was also synthesized under the same conditions. All of the polymers were characterized by means of spectrochemical (Fourier transform infrared spectroscopy, ¹H‐nuclear magnetic resonance (NMR), and ¹³C‐NMR) and thermal (differential scanning calorimetry and thermogravimetric) methods of analysis. Solubility of TPT polyamides was clearly improved due to the presence of the bulky aromatic diamine as well as flexible CH₂—CH₂ segments. The highly phenylated thiophene diamine moiety was recognized to improve thermal stability of the TPT polyamides in comparison with Ph polyamides (integral procedural decomposition temperature (IPDT) 480–517°C against 454–485°C). A favorable balance was recognized in regard to solubility, thermostability, and melting temperature in the TPT polyamides, especially TPT4 and TPT6. Therefore, they may be considered good candidates for processable polymers. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 1144–1153, 2000     

Treatment of paper and pulp wastewater and removal of odorous compounds by a Fenton‐like process at the pilot scale

A Fenton‐like process, involving oxidation and coagulation, was evaluated for the removal of odorous compounds and treatment of a pulp and paper wastewater. The main parameters that govern the complex reactive system [pH and Fe(III) and hydrogen peroxide concentrations] were studied. Concentrations of Fe(III) between 100 and 1000 mg L^?1 and of H₂O₂ between 0 and 2000 mg L^?1 were chosen. The main mechanism for color removal was coagulation. The maximum COD, color and aromatic compound removals were 75, 98 and 95%, respectively, under optimal operating conditions ([Fe(III)] = 400 mg L^?1; [H₂O₂] = 500–1000 mg L^?1; pH = 2.5; followed by coagulation at pH 5.0). The biodegradability of the wastewater treated increased from 0.4 to 0.7 under optimal conditions and no residual hydrogen peroxide was found after treatment. However, partially or non‐oxidized compounds present in the treated wastewater presented higher acute toxicity to Artemia salina than the untreated wastewater. Based on the optimum conditions, pilot‐scale experiments were conducted and revealed a high efficiency in relation to the mineralization of organic compounds. Terpenes [(1S)‐α‐pinene, β‐pinene, (1R)‐α‐pinene and limonene] were identified in the wastewater and were completely eliminated by the Fenton‐like treatment. Copyright © 2006 Society of Chemical Industry     

Chiral NCN Pincer Rhodium(III) Complexes with Bis(imidazolinyl)phenyl Ligands: Synthesis and Enantioselective Catalytic Alkynylation of Trifluoropyruvates with Terminal Alkynes

A series of new chiral C₂‐symmetrical NCN pincer rhodium(III) complexes with bis(imidazolinyl)phenyl ligands have been conveniently synthesized from easily available materials. The complexes were subsequently applied in the enantioselective addition of terminal alkynes to trifluoropyruvates. With catalyst loading of 1.5–3.0 mol%, the alkynylation of ethyl or methyl trifluoropyruvate with a variety of electronically and structurally diverse terminal alkynes gave the optically active trifluoromethyl‐substituted tertiary propargylic alcohols with enantioselectivities of up to >99% ee and high yields. Although good to excellent enantioselectivities (85–98% ee) could be achieved only for some of the aliphatic terminal alkynes under the optimized conditions, the enantioselectivities were consistently excellent (94% to >99% ee) in the case of aromatic as well as heteroaromatic alkynes and enynes.     

Metalloporphyrin/Iodine(III)‐Cocatalyzed Oxygenation of Aromatic Hydrocarbons

Hypervalent iodine species have a pronounced catalytic effect on the metalloporphyrin‐mediated oxygenations of aromatic hydrocarbons. In particular, the oxidation of anthracene to anthraquinone with Oxone readily occurs at room temperature in aqueous acetonitrile in the presence of 5–20 mol% of iodobenzene and 5 mol% of a water‐soluble iron(III)‐porphyrin complex. 2‐tert‐Butylanthracene and phenanthrene also can be oxygenated under similar conditions in the presence of 50 mol% of iodobenzene. The oxidation of styrene in the presence of 20 mol% of iodobenzene leads to a mixture of products of epoxidation and cleavage of the double bond. Partially hydrogenated aromatic hydrocarbons (e.g., 9,10‐dihydroanthracene, 1,2,3,4‐tetrahydronaphthalene, and 2,3‐dihydro‐1H‐indene) afford under these conditions products of oxidation at the benzylic position in moderate yields. The proposed mechanism for these catalytic oxidations includes two catalytic redox cycles: 1) initial oxidation of iodobenzene with Oxone producing the hydroxy(phenyl)iodonium ion and hydrated iodosylbenzene, and 2) the oxidation of iron(III)‐porphyrin to the oxoiron(IV)‐porphyrin cation‐radical complex by the intermediate iodine(III) species. The oxoiron(IV)‐porphyrin cation‐radical complex acts as the actual oxygenating agent toward aromatic hydrocarbons.     

Environment‐friendly chemical recycling of aliphatic polyurethanes by hydrolysis in a CO2‐water system

In order to develop a chemical recycling system of polyurethanes (PUs), environment‐friendly hydrolysis of two types of aliphatic PUs was studied under pressured CO₂ in water, in which the carbonic acid generated from CO₂ acted as an acid catalyst. Two PUs, namely H‐PU or I‐PU, were synthesized starting from 1,4‐butanediol and 1,6‐hexamethylene diisocyanate or isophorone diisocyanate, respectively. The hydrolysis of PUs depended on the experimental conditions, such as the temperature and CO₂ pressure. As a result, 98% of H‐PU and 91% of I‐PU were successfully hydrolyzed under the typical conditions of 190 °C for 24 h at 8.0 MPa CO₂. The reaction mixtures afforded 1,4‐butanediol and diamines without the formation of any byproducts. Both of these raw materials generated from the originated PUs by selective hydrolytic cleavage of the urethane linkages, and they were easily isolated in high yields simply by evaporation of the water‐soluble components within the reaction mixture. By comparing the results of the two aliphatic PUs with those of an aromatic PU (M‐PU), the hydrolyzability was found to decrease in the order H‐PU, I‐PU, and M‐PU. The difference can be ascribed to the hydrophilicity of the aliphatic or aromatic groups connected to the urethane moieties at the terminals of PUs. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45897.     

Synthesis and properties of new aromatic poly(ester‐imide)s derived from 4‐p‐biphenyl‐2,6‐bis(4‐trimellitimidophenyl) pyridine and various dihydroxy compounds

A novel class of wholly aromatic poly(ester‐imide)s, having a biphenylene pendant group, with inherent viscosities of 0.32–0.49 dL g^?1 was prepared by the diphenylchlorophosphate‐activated direct polyesterification of the preformed imide‐ring‐containing diacid, 4‐p‐biphenyl‐2,6‐bis(4‐trimellitimidophenyl)pyridine (1) with various aromatic dihydroxy compounds in the presence of pyridine and lithium chloride. A reference diacid, 2,6‐bis(trimellitimido)pyridine (2) without a biphenylene pendant group and two phenylene rings in the backbone, was also synthesized for comparison purposes. At first, with due attention to structural similarity and to compare the characterization data, a model compound (3) was synthesized by the reaction of compound 1 with two mole equivalents of phenol. Moreover, the optimum condition of polymerization reactions was obtained via a study of the model compound synthesis. All of the resulting polymers were characterized by Fourier transform infrared and ¹H NMR spectroscopy and elemental analysis. The ultraviolet λ_max values of the poly(ester‐imide)s were also determined. All of the resulting polymers exhibited excellent solubility in common organic solvents, such as pyridine, chloroform, tetrahydrofuran, and m‐cresol, as well as in polar organic solvents, such as N‐methyl‐2‐pyrrolidone, N,N‐dimethylacetamide, N,N‐dimethylformamide, and dimethyl sulfoxide. The crystalline nature of the polymers obtained was evaluated by means of wide‐angle X‐ray diffraction. The resulting poly(ester‐imide)s showed nearly an amorphous nature, except poly(ester‐imide) derived from 4,4′‐dihydroxy biphenyl. The glass transition temperatures (T_g) of the polymers determined by differential scanning calorimetry thermograms were in the range 298–342 °C. The 10% weight loss temperatures (T_10%) from thermogravimetric analysis curves were found to be in the range 433–471 °C in nitrogen. Films of the polymers were also prepared by casting the solutions. Copyright © 2006 Society of Chemical Industry     

Isothermal and nonisothermal crystallization kinetics of isotactic polypropylene nucleated with substituted aromatic heterocyclic phosphate salts

The crystallization kinetics of isotactic polypropylene (iPP) and nucleated iPP with substituted aromatic heterocyclic phosphate salts were investigated by means of a differential scanning calorimeter under isothermal and nonisothermal conditions. During isothermal crystallization, Avrami equation was used to describe the crystallization kinetics. Moreover, kinetics parameters such as the Avrami exponent n, crystallization rate constant Z_t, and crystallization half‐time t_1/2 were compared. The results showed that a remarkable decrease in t_1/2 as well as a significant increase in overall crystallization rate was observed in the presence of monovalent salts of substituted aromatic heterocyclic phosphate, while bivalent and trivalent salts have little effect on crystallization rate of iPP. The addition of monovalent metal salts could decrease the interfacial free energy per unit area perpendicular to PP chains σ_e value of iPP so that the nucleation rate of iPP was increased. During nonisothermal crystallization, Caze method was used to analyze the crystallization kinetics. It also showed that monovalent metal salts had better nucleation effects than bivalent and trivalent metal salts. From the obtained Avrami exponents of iPP and nucleated iPP it could be concluded that the addition of different nucleating agents changed the crystal growth pattern of iPP. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 3307–3316, 2006     

New Mono‐Quarternized Bis‐Cinchona Alkaloid Ligands for Asymmetric Dihydroxylation of Olefins in Aqueous Medium: Unprecedented High Enantioselectivity and Recyclability

New mono‐quaternized allyl bromide salts of bis‐Cinchona alkaloid ligands, [(QD)₂PHAL‐Allyl]Br and [(QN)₂PHAL‐Allyl]Br, have been synthesized which can be converted into their highly water‐soluble multihydroxylated derivatives under asymmetric dihydroxylation (AD) conditions and, thus, easily recovered by a simple extraction method after reaction and reused. These mono‐quaternized ligands exhibited superior catalytic efficiency to their neutral counterparts such as (DHQD)₂PHAL and (DHQ)₂PHAL for the AD reactions of mono‐ and disubstituted styrenes under Upjohn conditions. Merely 0.1 mol % of osmium was enough to complete the reactions of mono‐ and disubstituted styrenes and, moreover, these ligands showed the highest enantioselectivities (e.g., for styrene, 97 % ee with [(QD)₂PHAL‐Allyl]Br) among those ever achieved under Upjohn conditions.     

Direct synthesis of poly(4′‐oxy‐4‐biphenylcarbonyl) and poly(2‐oxy‐6‐naphthoyl) under nonstoichiometric conditions

Direct synthesis of poly(4′‐oxy‐4‐biphenylcarbonyl) (POBP) and poly(2‐oxy‐6‐naphthoyl) (PON) was examined by polycondensation of 4′‐hydroxy‐4‐biphenylcarboxylic acid (HBPA) and 2‐hydroxy‐6‐naphthoic acid (HNA) in the presence of 4‐ethoxybenzoic anhydride or 2‐naphthoic anhydride as condensation reagents. Polymerizations were carried out at 320 °C in aromatic solvents and liquid paraffin. POBP, having a number‐average degree of polymerization (DPn) of 38, was obtained as plate‐like crystals at the molar ratio of HBPA and anhydride of 50 mol%. PON was also obtained as plate‐like crystals but the DPn was only 13. HBPA and HNA were first converted to reactive acyloxyaromatic acid intermediates. Then the DPn was increased by means of reaction‐induced crystallization of oligomers and subsequent solid‐state polymerization via an acid–ester exchange under nonstoichiometric conditions caused by the monocarboxylic acid by‐product. Even though the DPn of PON was not as high, direct polycondensation of HBPA and HNA proceeded successfully with aromatic anhydrides. Copyright © 2004 Society of Chemical Industry     

Oxime Palladacycle‐Catalyzed Suzuki–Miyaura Alkenylation of Aryl,Heteroaryl, Benzyl,and Allyl Chlorides under Microwave Irradiation Conditions

A simple new protocol for the palladium‐catalyzed Suzuki–Miyaura cross‐coupling of organic chlorides under microwave irradiation is presented. Deactivated aryl and heteroaryl chlorides are efficiently cross‐coupled with alkenylboronic acids and potassium alkenyltrifluoroborates using the 4,4′‐dichlorobenzophenone oxime‐derived palladacycle 1b as precatalyst in 0.1 to 0.5 mol% palladium loading, tris(tert‐butyl)phosphonium tetrafluoroborate {[HP(t‐Bu)₃]BF₄} as ligand, tetra‐n‐butylammonium hydroxide as cocatalyst, and potassium carbonate as base in N,N‐dimethylformamide at 130 °C under microwave irradiation conditions. Under these conditions, styrenes, stilbenes, and alkenylarenes are obtained in good to high yields, and with high regio‐ and diastereoselectivities in only 20 min. The reported protocol is also very efficient for the regioselective alkenylation of benzyl and allyl chlorides to afford allylarenes and 1,4‐dienes.     

Synthesis,characterization, and soil biodegradation study of polyamides derived from the novel bioactive diacid monomer 5‐(2‐phthalimidoethanesulfonamido) isophthalic acid

A new bioactive diacid monomer, 5‐(2‐phthalimidoethanesulfonamido) isophthalic acid ( 6 ), was synthesized in three steps. This monomer can be regarded as biologically active aromatic diacid and may be used in the design of biodegradable and biological materials. This monomer was polymerized with several aromatic diamines by step‐growth polymerization to give a series of biodegradable and highly thermally stable polyamides (PAs) with good yield (70–82%) and moderate inherent viscosity between 0.38–0.68 dL/g in a system of triphenylphosphite/pyridine/N‐methyl‐2‐pyrolidone/CaCl_2. The new aromatic diacid 6 and all of the PAs derived from this diacid and aromatic diamines were characterized by Fourier transform infrared, ¹H‐NMR, ¹³C‐NMR, and elemental analysis techniques. The thermal stability of the PAs was determined by thermogravimetric analysis and differential scanning calorimetry techniques under a nitrogen atmosphere, and we found that they were moderately stable. The soil biodegradability behavior of 6 and all of the PAs derived from this diacid and aromatic diamines were investigated in culture media, and we found that the synthesized diacid 6 and all of the PAs were biodegradable under a natural environmental. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

MECHANISMS OF THE GAS-PHASE REACTIONS OF AROMATIC HYDROCARBONS AND PAHS WITH OH AND NO 3 RADICALS

Chemical removal for the simple monocyclic aromatic hydrocarbons (benzene and the C ₁ -C ₃ alkylbenzenes) and naphthalene and the C ₁ -C ₂ alkylnaphthalenes in the atmosphere is by reaction with hydroxyl (OH) radicals. Naphthalene and the C ₁ -C ₂ alkylnaphthalenes may also be removed, but to a much lesser extent, by reaction with nitrate (NO ₃ ) radicals. While rate constants for the gas-phase reactions of OH radicals and NO ₃ radicals with many of the simple monocyclic aromatic hydrocarbons and with naphthalene and the C ₁ -C ₂ alkylnaphthalenes have been measured, the detailed mechanisms of these OH radical-and NO ₃ radical-initiated reactions in the atmosphere are less well understood, especially for naphthalene and the alkylnaphthalenes. Here we present the available data on the reaction mechanisms occurring under laboratory conditions and attempt to reconcile these data with ambient atmospheric measurements. The OH radical reactions with benzene and alkylbenzenes and the OH radical and NO ₃ radical reactions with naphthalene and alkylnaphthalenes proceed mainly by initial addition of the OH or NO ₃ radical to the aromatic ring(s) at room temperature and below. The NO ₃ radical reactions with alkylbenzenes proceed by H-atom abstraction from the C-H bonds of the alkyl substituent group(s), while the NO ₃ radical reactions of naphthalene and the alkylnaphthalenes proceed by addition and with rates proportional to the NO ₂ concentration. The OH-monocyclic aromatic adducts react with O ₂ under atmospheric conditions, while the OH-naphthalene/alkylnaphthalene and NO ₃ -naphthalene/alkylnaphthalene adducts appear to undergo significant reaction with NO ₂ under urban atmospheric conditions.