HETEROGENEOUS REACTIONS OF OH RADICALS WITH PARTICULATE-PYRENE AND 1-NITROPYRENE OF ATMOSPHERIC INTEREST

The heterogeneous reactivity of OH radicals with pyrene and 1-nitropyrene adsorbed on model particles has been investigated using a discharge flow reactor, in the presence of a large excess of NO ₂ . Graphite was chosen as a simple model of carbonaceous particles, whereas silica was chosen as a representative surrogate of mineral atmospheric aerosol. The reaction kinetics was investigated by measuring the remaining pyrene and 1-nitropyrene adsorbed on particles after pressurized fluid extraction and gas chromatography/mass spectrometry analysis. Pseudo-first order rate constants were obtained from the fit of the experimental decay of particulate polycyclic compound concentrations versus reaction time. Rate constants were measured at room temperature for reactions of OH radicals with, respectively, pyrene, 1-nitropyrene, both adsorbed on silica, and 1-nitropyrene adsorbed on graphite, in the presence of NO ₂ .     

Chemistry of Secondary Organic Aerosol Formation from OH Radical-Initiated Reactions of Linear,Branched, and Cyclic Alkanes in the Presence of NO x

The effects of molecular structure on the products and mechanisms of SOA formation from OH radical-initiated reactions of linear, branched, and cyclic alkanes in the presence of NO _x were investigated in a series of environmental chamber experiments. SOA mass spectra were obtained in real time and off line using a thermal desorption particle beam mass spectrometer and used to identify reaction products. Real-time mass spectra were used to classify products according to their temporal behavior, and off-line temperature-programmed thermal desorption analysis of collected SOA was used to separate products by volatility prior to mass spectral analysis and to gain information on compound vapor pressures. A reaction mechanism that includes gas- and particle-phase reactions was developed that explains the formation of SOA products and is consistent with the various lines of mass spectral information. Results indicate that the SOA products formed from the reactions of linear, branched, and cyclic alkanes are similar, but differ in a few important ways. Proposed first-generation SOA products include alkyl nitrates, 1,4-hydroxynitrates, 1,4-hydroxycarbonyls, and dihydroxycarbonyls. The 1,4-hydroxycarbonyls and dihydroxycarbonyls rapidly isomerize in the particle phase to cyclic hemiacetals that then dehydrate to volatile dihydrofurans. This conversion process is catalyzed by HNO ₃ formed in the chamber and is slowed by the presence of NH ₃ . Volatile products can react further with OH radicals, forming multi-generation products containing various combinations of the same functional groups present in first-generation products. For linear and branched alkanes, the products are acyclic or monocyclic, whereas for cyclic alkanes they are acyclic, monocyclic, or bicyclic. Some of the products, especially those formed from ring-opening reactions of cyclic alkanes appear to be low volatility oligomers. The implications of the results for the formation of atmospheric SOA are discussed.     

Nitrate Radicals in Tropospheric Chemistry

Nitrate radicals are being recognized as key intermediates in a growing list of important chemical processes in the atmosphere. Here, the role of nitrate radicals (NO₃) in tropospheric chemistry is discussed, with special emphasis on results from field measurements, most of which have been made by differential optical absorption spectroscopy (DOAS), with matrix-isolation electron spin resonance being an alternative technique. Nitrate radicals were observed in the atmosphere at peak mixing ratios of 350 ppt. Long-term observation of NO₃ shows that 24-h averages in rural air masses are closer to a few ppt. Nevertheless, the NO₃ radical plays an important role in the non-photochemical conversion of NO_x to HNO₃. Also, NO₃ is a strong oxidizing agent and initiates the night-time removal of atmospheric trace species such as olefins, aromatic hydrocarbons, and organic sulfur compounds. Finally, night-time peroxy radical production and release of reactive halogen species from sea salt aerosol might be initiated by NO₃ reactions.     

Innovation of Hydrocarbon Oxidation with Molecular Oxygen and Related Reactions

An innovation of the aerobic oxidation of hydrocarbons through catalytic carbon radical generation under mild conditions was achieved by using N‐hydroxyphthalimide (NHPI) as a key compound. Alkanes were successfully oxidized with O₂ or air to valuable oxygen‐containing compounds such as alcohols, ketones, and dicarboxylic acids by the combined catalytic system of NHPI and a transition metal such as Co or Mn. The NHPI‐catalyzed oxidation of alkylbenzenes with dioxygen could be performed even under normal temperature and pressure of dioxygen. Xylenes and methylpyridines were also converted into phthalic acids and pyridinecarboxylic acids, respectively, in good yields. The present oxidation method was extended to the selective transformations of alcohols to carbonyl compounds and of alkynes to ynones. The epoxidation of alkenes using hydroperoxides or H₂O₂ generated in situ from hydrocarbons or alcohols and O ₂ under the influence of the NHPI was demonstrated and seems to be a useful strategy for industrial applications. The NHPI method is applicable to a wide variety of organic syntheses via carbon radical intermediates. The catalytic carboxylation of alkanes was accomplished by the use of CO and O₂ in the presence of NHPI. In addition, the reactions of alkanes with NO₂ and SO₂ catalyzed by NHPI provided efficient methods for the synthesis of nitroalkanes and sulfonic acids, respectively. A catalytic carbon‐carbon bond forming reaction was achieved by allowing carbon radicals generated in situ from alkanes or alcohols to react with alkenes under mild conditions. 1 Introduction 2 Discovery of NHPI as Carbon Radical Producing Catalyst from Alkanes 2.1 Historical Background 2.2 Catalysis of NHPI in Aerobic Oxidation 3 NHPI‐Catalyzed Aerobic Oxidation 3.1 Oxidation of Benzylic Compounds 3.2 Alkane Oxidations with Molecular Oxygen 3.3 Oxidation of Alkylbenzenes 3.4 Practical Oxidation of Methylpyridines 3.5 Preparation of Acetylenic Ketones via Alkyne Oxidation 3.6 Oxidation of Alcohols 3.7 Selective Oxidation of Sulfides to Sulfoxides 3.8 Production of Hydrogen Peroxide by Aerobic Oxidation of Alcohols 3.9 Epoxidation of Alkenes using Molecular Oxygen as Terminal Oxidant 4 Carboxylation of Alkanes with CO and O₂ 5 Utilization of NO_x in Organic Synthesis 5.1 First Catalytic Nitration of Alkanes using NO₂ 5.2 Reaction of NO with Organic Compounds 6 Sulfoxidation of Alkanes Catalyzed by Vanadium 7 Carbon‐Carbon Bond Forming Reaction via Catalytic Carbon Radicals Generated from Various Organic Compounds Assisted by NHPI 7.1 Oxyalkylation of Alkenes with Alkanes and Dioxygen 7.2 Synthesis of α‐Hydroxy‐γ‐lactones by Addition of α‐Hydroxy Carbon Radicals to Unsaturated Esters 7.3 Hydroxyacylation of Alkenes using 1,3‐Dioxolanes and Dioxygen 8 Conclusions     

Exploring formation pathways of aromatic compounds in laboratory-based model flames of aliphatic fuels

This presentation summarizes our recent experimental and flame modeling studies focusing on understanding of the formation of small aromatic species, which potentially grow to polycyclic aromatic hydrocarbons (PAHs) and soot. In particular, we study premixed flames, which are stabilized on a flat-flame burner under a reduced pressure of ≈15–30 torr, to unravel the important chemical pathways to aromatics formation in flames fueled by small C₃–C₆ hydrocarbons. Flames of allene, propyne, 1,3-butadiene, cyclopentene, and C₆H₁₂ isomers 1-hexene, cyclohexane, 3,3-dimethyl-1-butene, and methylcyclopentane are analyzed by flame-sampling molecular-beam time-of-flight mass spectrometry. Isomer-specific experimental data and detailed modeling results reveal the dominant fuel-destruction pathways and the influence of different fuel structures on the formation of aromatic compounds and their commonly considered precursors. As a specific aspect, the role of resonance-stabilized free radical reactions is addressed for this large number of similar flames of structurally different fuels. While propargyl and allyl radicals dominate aromatics formation in most flames, contributions from reactions involving other resonance-stabilized radicals like i-C₄H₅ and C₅H₅ are revealed in flames of 1,3-butadiene, 3,3-dimethyl-1-butene, and methylcyclopentane. Dehydrogenation processes of the fuel are found to be important benzene formation steps in the cyclohexane flame and are likely to also contribute in methylcyclopentane flames.     

Mechanistic Studies on the Dibenzofuran Formation from Phenanthrene,Fluorene and 9–Fluorenone

We carried out molecular orbital theory calculations for the homogeneous gas‑phase formation of dibenzofuran from phenanthrene, fluorene, 9-methylfluorene and 9-fluorenone. Dibenzofuran will be formed if ∙OH adds to C_8a, and the order of reactivity follows as 9-fluorenone > 9-methylfluorene > fluorene > phenanthrene. The oxidations initiated by ClO∙ are more favorable processes, considering that the standard reaction Gibbs energies are at least 21.63 kcal/mol lower than those of the equivalent reactions initiated by ∙OH. The adding of ∙OH and then O₂ to phenanthrene is a more favorable route than adding ∙OH to C_8a of phenanthrene, when considering the greater reaction extent. The reaction channel from fluorene and O₂ to 9-fluorenone and H₂O seems very important, not only because it contains only three elementary reactions, but because the standard reaction Gibbs energies are lower than −80.07 kcal/mol.     

Polymerization initiation by N-p-tolylglycine: Free-radical reactions studied by pulse and steady-state radiolysis

The extensive use of N-p-tolylglycine (NTG) and analogous compounds in adhesive bonding technologies requires a better understanding of their role in initiating free-radical polymerization. The fast oxidation and reduction reactions of NTG proceed via the formation of various free radicals and radical cation and anion intermediates. These intermediates were identified and their reactivity with oxygen, to produce the corresponding peroxyl radicals, was measured. Hydroxyl radicals (?H) were used to initiate oxidation reactions of NTG, while the reduction reactions were initiated with hydrated electrons (e). OH radicals react with NTG predominately by addition to the aromatic ring followed by OHÞ elimination to produce NTG⁺· radical cations. In the presence of oxygen, the OH–NTG^? adduct also reacts with oxygen to produce peroxyl radicals. The reaction of NTG with e forms the radical anion, which subsequently protonates on the aromatic ring to produce cyclohexadienyl radicals, or undergoes an amine elimination to yield an acetic acid free radical and 4-methylaniline. Hydroperoxyl radicals (HO) abstract hydrogen from the α position of NTG to form the corresponding alkyl free radical. © 1994 John Wiley & Sons, Inc.

1 This article is a US Government work and, as such, is in the public domain in the United States of America.

     

The Role of pH in the Mechanism of .OH Radical Induced Oxidation of Nicotine

The ^.OH radical induced oxidation of nicotine was studied using pulse radiolysis techniques from pH 1 to 13.6. Theoretical calculations were used to help interpret the experimental results. The bond dissociation enthalpies of all of the C H bonds of nicotine were determined using DFT calculations, coupled with the isodesmic reaction. From time-dependent density functional response theory, estimates were obtained of the location of the dominant transient absorption bands (λ_max), their intensities (electronic oscillator strength, f), and the electronic composition of these transitions. OH radicals as well as other potent oxidants reacted with free nicotine through separated, concerted electron proton transfer, leading mostly to the formation of an alpha-aminoalkyl radical located on the C_2′ carbon of the aliphatic ring ( A_2′ ). Protonated nicotine underwent hydrogen atom abstraction at the C_2′ and N_1′ positions, resulting in the formation of the conjugate acid of A_2′ ( A_2′H⁺ ) and the alkylamine radical cation ( N⁺ ), respectively. Doubly protonated nicotine underwent the same reaction pathways, leading to two corresponding conjugate acid species, protonated at the aromatic nitrogen position: PyrH⁺A_2′H⁺ and PyrH⁺N⁺ _. All these radicals interconverted between each other through hydrolytic reactions. The radical A_2′ and its conjugate acid PyrH⁺A_2′ absorbed 10 times stronger than the N⁺ species, based on calculations of f. From the growth of the transient absorption of A_2′ (λ_max=330 nm, ε=8080 M ⁻¹ cm⁻¹), second-order rate constants were determined: k_(OH+Nic)=6.7×10⁹ M ⁻¹ s ⁻¹, k_(OH+NicH)=1.0×10⁹ M ⁻¹ s⁻¹. The alpha-aminoalkyl radicals decayed by disproportionation to form iminium cations 1 – 5 , which contributed to an increase in the specific conductivity of the basic solutions of nicotine following electron pulse irradiation.     

ATMOSPHERIC OCCURRENCE OF 2-NITROBENZANTHRONE ASSOCIATED WITH AIRBORNE PARTICLES IN CENTRAL TOKYO

2- and 3-Nitrobenzanthrones (NBAs) in airborne particles collected in central Tokyo on a seasonal basis from 1996 to 2001 are quantified and possible sources are investigated. The concentrations of 2- and 3-NBA are found to range from 49 to 831 fmol m^–3and 0.5 to 3.5 fmol m^–3, while the nitrated polycyclic hydrocarbons 1-nitropyrene and 2-nitrofluoranthene are found at concentrations of 100–492 fmol m^–3 and 10–97 fmol m^–3. Significant linear correlations are identified between 2-NBA and NO₂, a photochemical product, suggesting that 2-NBA is formed by atmospheric reactions of benzanthrone initiated by hydroxyl or nitrate radicals in the presence of NO₂. 2-NBA is not correlated with directly emitted compounds such as 1-nitropyrene. The concentration ratio of 2-NBA to 1-nitropyrene is 5 or greater in all samples. Nitrated polycyclic aromatic compounds formed by atmospheric reactions therefore appear to represent a substantial contribution to the mutagenicity of airborne particulate matter.     

The Chemical Background of Advanced Oxidation Processes

In advanced oxidation processes, the hydroxyl radical is the main initiator of the degradation of pollutants. For aromatic molecules, the rate coefficients are between 2×10⁹ and 1×10¹⁰ mol⁻¹ dm³ s⁻¹ and show some variation according to the electron-withdrawing or donating nature of the substituents. The one-electron oxidant ^.OH induces 2–4 electron oxidations of many aromatic pollutants. These high rates are explained by ^.OH addition to an unsaturated bond, scavenging of the organic radical by dissolved O₂, and subsequent reactions. In amino-substituted molecules and in azo dyes the efficiency is lower, because O₂ cannot compete efficiently with the unimolecular transformation of carbon-centered radicals. Generally, the toxicity first increases and then decreases with treatment time. The increase is attributed to the high toxicity of some degradation products and to H₂O₂ formation. In surface waters, traces of transition metal ions degrade some of the H₂O₂ in Fenton-like processes.     

Reactions of Methylated Naphthalenes with Hydroxyl Radicals Under Simulated Atmospheric Conditions

The gas-phase reactions of OH with 1- and 2-methylnaphthalene, 1,3- and 2,3-dimethylnaphthalene, acenaphthylene and acenaphthene were investigated under simulated atmospheric conditions in a 10m³ smog chamber. The rates of reaction, relative to naphthalene = 1.0, were 1-methylnaphthalene, 1.5; 2-methylnaphthalene, 2.1; 1,3-dimethylnaphthalene, 0.9; 2,3-dimethylnaphthalene, 0.9; acenaphthene, 2.9; and acenaphthylene, 5.8. Solid phase microextraction (SPME) in combination with gas chromatography/mass spectrometry (GC/MS) was used to analyze the organic reaction products, thus avoiding the production of artifacts observed in the previously used cold finger trapping procedure. Reaction products were mainly homologs of those formed in the reaction of naphthalene with OH radicals.     

The method for surface functionalization of single-walled carbon nanotubes with fuming nitric acid

Surface functionalization of single-walled carbon nanotubes (SWCNTs) was carried out using fuming nitric acid as a NO₂ radical source. The surface double bonds of the SWCNTs reacted with the NO₂ radicals at 10–90 °C under sonication, and following treatment with aqueous NaOH yielded modified carbon nanotubes with high affinity for polar solvents such as dimethylformamide. The structure of the product was characterized using Fourier transform-infrared spectroscopy (FT-IR), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis, and atomic force microscopy. FT-IR and XPS spectra revealed the product has OH groups (3400, 1200 cm⁻¹), which was expected due to the addition of NO₂ radicals to the surface double bonds and subsequent substitution with OH groups. C_1s curve fitting analysis of the XPS spectra was used to quantitatively determine the different functional groups on the surface, and the amount of COOH groups was found to be increased from 2.8% to 9.3% due to progressive oxidation by increasing the reaction temperature from 10 to 90 °C.     

New anionic alkylaryl surfactants based on olefin sulfonic acids

A new family of anionic surfactants has been produced by the simultaneous sulfonation and alkylation of aromatic compounds using olefin sulfonic acid(s). This new process does not require the conventional alkylation unit and the strong acid catalysts, such as AlCl₃ or HF, normally used for alkylation. The resulting alkylaryl sulfonic acids differ from existing prodeucts by having the sulfonate group attached to the alkyl chain rather than the aromatic ring. This allows for further derivatization of the aromatic compounds by leaving more positions open on the ring. Aromatic compounds that lend themselves to the new process include benzene, toluene, xylene, alkylbenzenes, phenol, alkylphenols, alkoxylated phenols, alkoxylated alkylphenols, alkoxylated alkylphenol/formaldehyde resins, naphthalene, and alkylnaphthalenes. Any type of olefin that can be sulfonated can be used as the starting material. These include internal and α-olefins, linear and branched olefins, polyolefins, and vinylidenes. Mono- and disulfonated compounds, as well as geminitype surfactants, are easily prepared.     

NO x -Catalyzed Gas-Phase Activation of Methane: In Situ IR and Mechanistic Studies

The products of reactions occurring in a CH₄–O₂–NO _x mixture have been investigated by in situ FTIR spectroscopy. The results show that low temperatures favor the formation of HCHO and CH₃OH, while high temperatures favor that of C₂H₄. Possible reaction mechanisms based on the in situ observations are briefly discussed.     

Chemical reactions in the low-temperature zone of a laminar rich propane—air flame

The mechanism of chemical reactions in the low-temperature zone of a rich propane—air flame is considered. It is shown that at temperatures of 300–700 K, intense chemical reactions proceed with the formation of end products and that the water concentration reaches an intermediate equilibrium value even at a temperature of 685 K. In this zone of the front, the diffusion of atomic hydrogen from the high-temperature zone plays a determining role and water is formed mainly by the reactions H + O₂ + M ⇒ HO₂ + M, HO₂ + HO₂ ⇒ H₂O₂ + O₂, H₂O₂ (+M) ⇒ 2OH (+M), C₃H₈ + OH ⇒ C₃H₇ + H₂O. Propane reacts with active centers more effectively than molecular hydrogen. Its primary reactions are due to the interaction with OH and HO₂ radicals. Arguments are given in favor of the thermal-diffusion nature of the superadiabatic temperature phenomenon in rich propane—air flames. __________ Translated from Fizika Goreniya i Vzryva, Vol. 42, No. 5, pp. 14–19, September–October, 2006.     

Benzophenone vs. Copper/Benzophenone in Light‐Promoted Atom Transfer Radical Additions (ATRAs): Highly Effective Iodoperfluoroalkylation of Alkenes/Alkynes and Mechanistic Studies

Iodoperfluooralkylation of terminal alkenes and alkynes is effectively photo‐promoted by benzophenone 2 (BP) or the photoreducible copper(II) complex 1 . In particular, BP at 1 mol% in methanol upon 365 nm irradiation with a low‐pressure mercury lamp (type TLC=thin layer chromatography, 6 W) results in a fast reaction with excellent reaction yields. Complex 1 and BP 2 exhibited very similar reactivity, suggesting that the reactions involving 1 are likely to be governed by the benzophenone photoactivation processes, rather than copper(I)/(II) redox processes. Mechanistic investigations using transient absorption spectroscopy revealed that a deactivation pathway of the benzophenone triplet (³BP*) is via its reaction with the methanol solvent. We propose that the generated radicals, in particular ^.CH₂OH, play a key role in the initiation step forming R_f^. by reacting with R_fI, R_f^. then entering a radical chain cycle. ¹H NMR studies provided evidence that a substantial amount (∼7% NMR yield) of the hemiacetal CH₃OCH₂OH is formed, i.e., the possible by‐product of the reaction between ^.CH₂OH and R_fI. Finally, DFT calculations indicate that a triplet‐triplet energy transfer (TTET) process from ³BP* to perfluorooctyl iodide (C₈F₁₇I) is unlikely or should be rather slow under the reaction conditions, consistent with the transient absorption studies.

     

Study of the coupling reactions between electrochemically generated aromatic radical anions and methyl, alkyl and benzyl radicals

Alkyl radicals produced in the indirect reduction of alkyl halides or alkyldimethylsulfonium salts by electrochemically generated aromatic radical anions couple fast with the latter and alkylated or dialkylated dihydro compounds are formed. Rate constants measured for the coupling reaction between on one hand methyl, primary, secondary and tertiary alkyl radicals as well as benzyl and cumyl radicals and on the other hand a wide spectrum of electrochemically generated aromatic radical anions are found to be about 1×10⁹ M⁻¹ s⁻¹. Previous measurements of coupling rate constants for primary alkyl radicals have been re-evaluated since they were affected by the presence of an S_N2 reaction occurring between the alkyl halides used as radical precursors and the aromatic radical anions. New experiments are also included using alkyldimethylsulfonium salts as precursors in order to prevent such S_N2 artefacts. It is concluded that sterical hindrance does not play a significant role for the radical-radical anion coupling reactions. In general the rate constants for the coupling reactions are all close to 10⁹ M⁻¹ s⁻¹.     

Chemical Mechanisms of Aging of Aerosol Formed from the Reaction of n-Pentadecane with OH Radicals in the Presence of NOx

The effects of aging via gas-phase oxidation and heterogeneous/multiphase reactions on the composition and volatility of secondary organic aerosol (SOA) were investigated in a series of environmental chamber experiments. SOA was formed from the reaction of n-pentadecane, a C₁₅ intermediate volatility alkane, with OH radicals in the presence of NO_x under conditions corresponding to ～1.5 and ～15 h of daytime oxidation, and analyzed using a suite of real-time and offline methods. Functional group analysis indicated that the average number of nitrate, hydroxyl, carbonyl, carboxyl, ester, acylperoxynitrate, and methylene groups per C₁₅ molecule were 0.84, 1.07, 0.25, 0.00, 0.00, 0.00, and 12.84 in less aged SOA and 1.25, 0.69, 0.32, 0.00, 0.33, 0.10, and 12.27 in more aged SOA, and the corresponding O/C, H/C, and N/C ratios determined by offline elemental analysis were 0.32, 2.20, and 0.062, and 0.31, 1.86, and 0.061, respectively, similar to each other and in good agreement with values calculated from functional group composition. Time-dependent SOA yields and temperature-programmed thermal desorption (TPTD) analysis showed that the more aged SOA was much less volatile and more chemically complex, and when combined with particle mass spectra indicated that the major SOA components included 1,4-hydroxynitrates, cyclic hemiacetals (CHA), cyclic hemiacetal nitrates (CHAN), and related compounds, as well as hemiacetal (HA) and acetal oligomers. The effects of aging on functional group composition were due primarily to dehydration of CHA and formation of second- and third-generation products via gas-phase OH radical reactions, whereas SOA volatility was reduced primarily by enhanced formation of HA and acetal oligomers through heterogeneous/multiphase reactions involving these multigeneration products. These results can be explained using well-established gas-phase and heterogeneous/multiphase reaction mechanisms.

Copyright 2013 American Association for Aerosol Research     

Formation of C m H n (m ≥ 3, n ≤ m) hydrocarbons from C1 and C2 molecules by high‐temperature (≥1000°C), short‐contact‐time (1–10 ms) nozzle beam reactions

A nozzle, fabricated from nickel, molybdenum, iron, palladium, and quartz was utilized to produce longer chain hydrocarbons, C _m H _n (m ≥ 3, n≤ m) from C₂ (ethane, acetylene) and C₁ (methane) reactants at nozzle temperature range 1000–1150°C. The conversion of ethane was close to 100% at T _noz = 1000°C, while that of methane reached 20% at T _noz = 1150°C. The contact time in the nozzle is in the 10^-3–10^-2 s range. The reactions are first and higher order in reactant pressure. The reaction mechanism involves the formation of free radicals at the nozzle surface followed by gas‐phase reactions. This revised version was published online in July 2006 with corrections to the Cover Date.     

Opening of the rings of aromatic and naphthene hydrocarbons: A new way of improving the quality of fuels

In recent years, the opening of the rings of aromatic and naphthene hydrocarbons has been considered as a way way of improving the quality of motor fuels. In gasolines, the opening of monocyclic compounds like di- and trialkylcyclohexanes allows the synthesis of high-octane components (C₇–C₁₀ iso-paraffins). In diesel fuels containing considerable amounts of bi- and trinuclear polycyclic compounds such as derivatives of naphthalene (decaline), phenanthrene, and indane, this allows the synthesis of monocyclic compounds and alkanes, thus leading to a reduction in the freezing temperature of the fuel and, when obtaining predominantly linear alkanes, to an increase in the cetane number. In this work, we conduct a brief analysis of accumulated data on the opening of cyclic compounds on oxide and zeolite supported catalysts.