Presence Of N-hydroxyphthalimide Research Articles

Highly efficient and organic nitrogen-containing cation-promoted aerobic oxidation of alkylaromatics in the presence of N-hydroxyphthalimide

BACKGROUD: Direct oxidation of alkylaromatics to the corresponding aromatic ketone is an important process in the manufacture of perfumes, pharmaceuticals, flavors, dyes and agrochemicals. For example, tetralin is oxidized to produce 1-tetralinone, which is a key intermediate in the commercial production of 1-naphthol, 2-hydroxy-1-tetralone, aureolic acid antibiotics and other pharmaceuticals. RESULTS: In this investigation, it was found that alkylaromatics could be efficiently and selectively oxidized to the corresponding aromatic ketones when methyl violet was employed as a promotor in the presence of N-hydroxyphthalimide (NHPI); tetralin was oxidized with 89% conversion and 76% selectivity to 1-tetralinone under 0.3 MPa of O2 at 75 °C for 2.5 h. The effects of temperature, oxygen pressure, reaction time and additive inclusion were studied in detail. A possible reaction mechanism for tetralin oxidation has been proposed. CONCLUSION: It was demonstrated that methyl violet could efficiently promote the aerobic oxidation of alkylaromatics in the presence of NHPI under mild conditions. Further investigations indicated that the nitrogen cation had a crucial promotion effect in the oxidation process. Copyright © 2009 Society of Chemical Industry

Mechanisms of the C-H halogenation of adamantane in the presence of N-hydroxyphthalimide

A study was carried out on the mechanisms for the halogenation of the C-H bonds in systems containing N-hydroxyphthalimide, oxone, and CHal4 or N-hydroxyphthalimide and t-BuOCl. These reactions proceed with the participation of the phthalimido-N-oxyl (PINO) radical, which may serve either as an initiator or reagent. A DFT (density functional theory) model showed that the PINO radical may be generated efficiently in the presence of t-BuOCl as the initiator.

New Strategies for Sulfate-Free Synthesis of Lactams from Cycloalkanes Using NHPI as a Key Catalyst

New strategies for lactams synthesis from cycloalkanes without formation of sulfates have been proposed. The synthesis of lactams from cycloalkanes through a one-pot reaction was successfully performed using N-hydroxyphthalimide (NHPI) as a key catalyst. The strategy involves nitrososation of cycloalkanes with tert-butyl nitrite under the influence of NHPI followed by isomerization to oximes and then the Beckmann rearrangement to lactams. For example, e-caprolactam and laurolactam were prepared from cyclohexane and cyclododecane in 74% and 78% yields, respectively, in one-pot. An alternative approach for sulfate-free lactam synthesis includes the nitration of cyclohexane with NO2 to nitrocyclohexane in the presence of NHPI under mild conditions followed by the hydrogenation to cyclohexanone oxime. The Beckmann rearrangement to .e-caprolactam was found to be achieved in quantitative yields by a very small amount of cyanuric chloride in a mixed solvent of trifluoroacetic acid and toluene.

One‐Pot Synthesis of Lactams from Cycloalkanes and tert‐Butyl Nitrite by Using N‐Hydroxyphthalimide as Key Catalyst

Lactams were successfully synthesized in the one-pot reaction of cycloalkanes and tBuONO in the presence of N-hydroxyphthalimide as a key catalyst. Cyclododecane and cyclohexane were treated with tBuONO followed by triethylamine and then cyanuric chloride in a one-pot manner to give laurolactam and epsilon-caprolactam, respectively, in good yields. The Beckmann rearrangement of oximes by cyanuric chloride was found to be accelerated by the use of 1,1,1,3,3,3-hexafluoro-2-propanol as solvent. The method provides the first successful environmentally benign direct synthetic route to lactams from cycloalkanes without the formation of any salt.

Highly Efficient and Metal‐Free Aerobic Hydrocarbons Oxidation Process by an o‐Phenanthroline‐Mediated Organocatalytic System

AbstractA highly efficient o‐phenanthroline‐mediated, metal‐free catalytic system has been developed for oxidation of hydrocarbons with dioxygen in the presence of N‐hydroxyphthalimide; various hydrocarbons were efficiently and high selectively oxidized, e.g., ethylbenzene to acetophenone in 97% selectivity and 76% conversion, under mild conditions.

An improved protocol for aerobic oxidation of acetals to esters catalyzed by N-hydroxy phthalimide (NHPI) and lipophilic Co(II) complexes

In this work the effect of lipophilization of Co(II) ions on the rate of the aerobic oxidation of acetals to esters in the presence of N-hydroxy phthalimide (NHPI) was investigated. The catalysts that were used in this work are Co(OAc) 2 ( 1a), Co(OCOC 5H 11) 2 ( 1b), Co(OCOC 6H 5) 2 ( 1c), Co(OCOC 9H 19) 2 (1d), Co(OCOC 17H 35) 2 ( 1e). It has been found that among the described Co(II) salts, both 1b and 1c were better suited than the other cobalt carboxylates in catalyzing of aerobic oxidation of acetals in the presence of NHPI. The probable role of the carboxylate ligands were also briefly discussed.

Novel Method for Efficient Aerobic Oxidation of Silyl Ethers to Carbonyl Compounds Catalyzed with N‐Hydroxyphthalimide (NHPI) and Lipophilic Co(II) Complexes.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Novel method for efficient aerobic oxidation of silyl ethers to carbonyl compounds catalyzed with N-hydroxyphthalimide (NHPI) and lipophilic Co(II) complexes.

In this work, a new method for highly efficient and selective oxidative deprotection of a variety of structurally diverse trimethylsilyl (TMS) and tert-butyldimethylsilyl (TBS) ethers using molecular oxygen in the presence of N-hydroxyphthalimide (NHPI) and various types of Co(II) complexes is reported. As a result of the relatively neutral reaction medium, acid-sensitive functional groups such as phenolic TBS ethers survived intact under the presented reaction conditions.

Mechanism of the catalytic oxidation of hydrocarbons by N-hydroxyphthalimide: a theoretical studyElectronic supplementary information (ESI) available: all discussed TS and important intermediates (geometries, energies, ZPE, rotational constants and frequencies). See http://www.rsc.org/suppdata/cc/b4/b401050g/

The mechanism of the recently proposed catalytic oxidation of hydrocarbons by oxygen in the presence of N-hydroxyphthalimide (NHPI) was established by quantum chemical calculations, consistent with experiments.

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 NOx 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

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 NOx 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

Direct Conversion of Cyclohexane into Adipic Acid with Molecular Oxygen Catalyzed by N-Hydroxyphthalimide Combined with Mn(acac)2 and Co(OAc)2

Direct conversion of cyclohexane into adipic acid was achieved by the use of the radical catalyst, N-hydroxyphthalimide (NHPI), in the presence of a small amount of a transition metal. For instance, cyclohexane could be converted into adipic acid in 73% selectivity at 73% conversion under atmospheric oxygen (1 atm) in the presence of NHPI (10 mol %) and Mn(acac)2 (1 mol %) at 100 °C for 20 h. ESR measurements show that the formation of phthalimide N-oxyl generated from NHPI with O2 was assisted by Co(II) species. Thus, the oxidation of cyclohexane to adipic acid was found to be enhanced by the addition of a small amount of Co(OAc)2 to the NHPI/Mn(acac)2 system. The NHPI-catalyzed oxidation of cyclohexane provides an attractive direct method which has long been desired in the chemical industry for the manufacturing of adipic acid. The present oxidation seems to be the first practical environmentally friendly process, in which nitric acid is not used as the oxidant, for the production of adipic acid from cyclohexane.

N-hydroxyphthalimide (NHPI)-catalyzed reaction of adamantane under nitric oxide atmosphere

The reaction of adamantane under atmospheric nitric oxide in the presence of N-hydroxyphthalimide (NHPI) which serves as the radical catalyst in a mixed solvent of benzonitrile and acetic acid afforded 1- N-adamantylbenzamide as a principal product along with small amounts of 1-nitroadamantane and 1-hydroxyadamantane. On the other hand, 1-nitroadamantane was obtained in good yield upon treatment of adamantane with NO O 2 .

A novel catalysis of N-hydroxyphthalimide (NHPI) combined with Co(acac) n ( n = 2 or 3) in the oxidation of organic substrates with molecular oxygen

A novel class of catalysts for aerobic oxidation for a wide variety of organic substrates was developed. Benzylic compounds such as fluorene were oxidized with molecular oxygen in the presence of N-hydroxyphthalimide (NHPI) to give the corresponding oxygenated products such as fluorenone. For the oxidation of cycloalkanes, polycyclic alkanes and alkylbenzenes, which are difficult to be oxidized by NHPI alone, a combined catalytic system of NHPI with Co(acac) n ( n = 2 or 3) was found to be efficient for the oxidation of these substrates. Thus cycloalkanes were successfully oxidized with dioxygen in the presence of a catalytic amount of NHPI (10 mol%) and Co(acac) 2 (0.5 mol%) in acetic acid at 100°C to give cycloalkanones and dicarboxylic acids as principal products. Alkylbenzenes were also oxidized by this catalytic system to form the corresponding carboxylic acids and/or carbonyl compounds in good yields. Exposure of NHPI to atmospheric oxygen in benzonitrile at 80°C generated phthalimide N-oxyl (PINO), a key intermediate, in this oxidation. The formation of PINO from the NHPI and dioxygen was significantly accelerated by adding Co(acac) 2 to the reaction system.

Hydroxylation of polycyclic alkanes with molecular oxygen catalyzed by N-hydroxyphthalimide (NHPI) combined with transition metal salts

Adamantanes were successfully converted into the corresponding mono- and dihydroxy adamantanes with molecular oxygen in the presence of N-hydroxyphthalimide (NHPI) combined with cobalt salts under mild conditions. For example, exposure of adamantane under oxygen atmosphere in the presence of NHPI (10 mol%) and Co(acac) 2 (0.5 mol%) in acetic acid at 75 °C for 6 h afforded adamantan-1-ol (43 %) and adamantane-1,3-diol (40 %) along with adamantan-2-one (8 %) in 93 % conversion. Similarly, 1,3-dimethyladamantane produced 3,5-dimethyladamantan-1-ol (47 %) and 5,7-dimethyladamantane-1,3-diol (37 %).

5505920 Process for treatment of waste gas from a cyclohexane oxidation reactor

A novel class of catalysts for aerobic oxidation for a wide variety of organic substrates was developed. Benzylic compounds such as fluorene were oxidized with molecular oxygen in the presence of N-hydroxyphthalimide (NHPI) to give the corresponding oxygenated products such as fluorenone. For the oxidation of cycloalkanes, polycyclic alkanes and alkylbenzenes, which are difficult to be oxidized by NHPI alone, a combined catalytic system of NHPI with Co(acac)n (n = 2 or 3) was found to be efficient for the oxidation of these substrates. Thus cycloalkanes were successfully oxidized with dioxygen in the presence of a catalytic amount of NHPI (10 mol%) and Co(acac)2 (0.5 mol%) in acetic acid at 100°C to give cycloalkanones and dicarboxylic acids as principal products. Alkylbenzenes were also oxidized by this catalytic system to form the corresponding carboxylic acids and/or carbonyl compounds in good yields. Exposure of NHPI to atmospheric oxygen in benzonitrile at 80°C generated phthalimide N-oxyl (PINO), a key intermediate, in this oxidation. The formation of PINO from the NHPI and dioxygen was significantly accelerated by adding Co(acac)2 to the reaction system.

Anodic oxidation of compounds having benzylic or allylic carbon and .ALPHA.-carbon to hetero atom using N-hydroxyphthalimide as a mediator.

Benzylic, allylic carbons and the carbon α to hetero atoms are electrochemically oxidized to the corresponding carbonyl group in the presence of N-hydroxyphthalimide under mild conditions.