Use Of N-hydroxyphthalimide Research Articles

Kinetic Study of <i>para</i>-<i>tert</i>-Butylcumene Oxidation in the Presence of <i>N</i>-Hydroxyphthalimide

The kinetics of the oxidation of para-tert-butylcumene to hydroperoxide by molecular oxygen in the presence of N-hydroxyphthalimide has been studied. Based on the study of the regularities in the formation of hydroperoxide and non-target reaction products, a mathematical model of the process was obtained that adequately describes the change in the main components of the reaction concentration over time. The main role of N-hydroxyphthalimide is that it converts peroxide radicals into the corresponding hydroperoxides, thereby reducing the formation of non-target reaction products by reducing the quadratic termination rate. Simultaneously formed N-oxyphthalimide radicals increase the rate of hydrocarbon oxidation. Thus, the use of N-hydroxyphthalimide in hydrocarbon oxidation processes results in an increase in the rate and selectivity of hydroperoxide formation.

Direct Tertiary Butyl Alcohol Formation via Catalytic Liquid Phase Isobutane Oxidation with Molecular Oxygen

A safe one-pot catalytic process for directly producing tertiary butyl alcohol (TBA) from liquid-phase isobutane oxidation with oxygen is demonstrated. This is achieved by operating outside the vapor phase flammability envelope and catalytically decomposing tertiary butyl hydroperoxide (TBHP), the main product of homogeneous isobutane oxidation, at 125 °C and 35 bar. Among a dozen heterogeneous metal-based catalysts tested, amorphous MnO2 (AMO) was found to be roughly an order of magnitude more active than supported Pd, Co, Au, and Nb-based catalysts for TBHP decomposition to TBA. As a result, high TBA/TBHP (up to 20.4) selectivity was achieved during isobutane oxidation in the presence of the AMO catalyst. The yield of gas phase C1 products was <1% and only a minor amount of acetone was produced as a β-scission byproduct. The use of n-hydroxy phthalimide (NHPI) as an initiator was found to enhance the TBA yield. This process provides a possible low energy pathway for making isobutylene from isobutane, avoiding the energy-intensive dehydrogenation and isobutane/isobutylene separation steps.

Metal-Free Synthesis of Adipic Acid via Organocatalytic Direct Oxidation of Cyclohexane under Ambient Temperature and Pressure

A direct metal-free approach for the production of adipic acid from cyclohexane is reported. The use of N-hydroxyphthalimide (NHPI) as a catalyst in the presence of HNO3/TFA enables the direct oxidation of cyclohexane to yield adipic acid under ambient temperature and pressure via a simple procedure. This reaction proceeds through an initial oxidation of cyclohexane to cyclohexanone oxime and cyclohexanone followed by a second oxidation of these intermediates to adipic acid. NHPI plays a crucial role in both oxidation steps to achieve a high yield and selectivity for adipic acid.

INTENSIFICATION OF THE CYCLOHEXANE LIQUID PHASE OXIDATION PROCESS

Liquid-phase oxidation of cyclohexane to cyclohexanol and cyclohexanone was studied in the absence of solvents under an air pressure of 0.5-5 MPa, in the temperature range 115-150 °C, catalyzed by N-hydroxyphthalimide (N-HPI). It was established for the first time that the use of N-HPI as a catalyst in place of the conventionally used metal salts of variable valence allowed a 2-3-fold increase in the conversion of the initial hydrocarbon and selectivity from 70-75 to 90%. The combined use of N-HPI with cobalt(II) acetate results in an additional increase in the conversion of cyclohexane by 30-40%, the selectivity of cyclohexanol and cyclohexanone formation to 94-97%, which seems to be due to the synergistic effect between the two components of the catalyst. The mechanism of catalytic oxidation of cyclohexane to cyclohexanol and cyclohexanone is discussed. It has been suggested that N-HPI plays a dual role in the oxidation of cyclohexane: it catalyzes the conversion of cyclohexane to cyclohexanol and cyclohexanone and, on the other hand, promotes the conversion of cyclohexanol to cyclohexanone, thereby substantially reducing the formation of adipic acid and its esters, by-products of the reaction, and increases selectivity of oxidation. This also explains the unusually high (1.3-1.5 : 1) ketone: alcohol ratio in the oxidation products of cyclohexane in the presence of N-HPI. The high selectivity of the formation of the desired products, the conversion of cyclohexane, the moderate temperature, the available catalyst, suggest that this method of oxidizing cyclohexane to cyclohexanol and cyclohexanone may be of interest for further practical use.

N-Hydroxyphthalimide-Mediated Electrochemical Iodination of Methylarenes and Comparison to Electron-Transfer-Initiated C-H Functionalization.

An electrochemical method has been developed for selective benzylic iodination of methylarenes. The reactions feature the first use of N-hydroxyphthalimide as an electrochemical mediator for C-H oxidation to nonoxygenated products. The method provides the basis for direct (in situ) or sequential benzylation of diverse nucleophiles using methylarenes as the alkylating agent. The hydrogen-atom transfer mechanism for C-H iodination allows C-H oxidation to proceed with minimal dependence on the substrate electronic properties and at electrode potentials 0.5-1.2 V lower than that of direct electrochemical C-H oxidation.

Synthesis of amino acid conjugates of glycyrrhizic acid using N-hydroxyphthalimide and N,N'-dicyclohexylcarbodiimide.

Synthesis of amino acid conjugates of glycyrrhizic acid with the use of N-hydroxyphthalimide, N,N'-dicyclohexylcarbodiimide, and tert-butyl esters of L-amino acids (valine, isoleucine, phenylalanine, and methionine) was performed followed by deprotection with trifluoroacetic acid. The target amino acid conjugates were isolated by column chromatography on silica gel in 40–45% yield. The structure of the prepared compounds was confirmed by IR and 13C NMR spectroscopy.

Intensifying the oxidation of isopropylbenzene

The reaction of liquid-phase oxidation of isopropylbenzene in the presence of nitrogen-containing catalysts at 110–130°C was studied. It was found that by using N-hydroxyphthalimide and its 3- and 4-methyl-substituted analogs, a 40–50% conversion of isopropylbenzene can be attained in 2–2.5 h with 90% selectivity of hydroperoxide formation. Considering the amount of phenol production, solving the problem of intensifying isopropylbenzene oxidation through the use of N-hydroxyphthalimide, thereby increasing the reaction rate and hydrocarbon conversion while retaining a high selectivity of hydroperoxide formation, could considerably enhance the economic parameters of the process.

Recent progress in aerobic oxidation of hydrocarbons by N-hydroxyimides

Innovative carbon radical generation from hydrocarbons through a catalytic process under mild conditions has been achieved by the use of N-hydroxyphthalimide (NHPI) as a catalyst. This method can be successfully applied to a wide variety of functionalizations of hydrocarbons. Thus, alkanes are converted into alcohols, ketones, and carboxylic acids, through alkyl radicals generated by the action of NHPI. Cyclohexane was directly converted into adipic acid with O 2 by NHPI combined with Mn(OAc) 2. p-Xylene was oxidized to terephthalic acid in 95% yield by using an NHPI analogue as a catalyst. Alkenes could be epoxidized with H 2O 2 generated in situ from benzhydrol and O 2 under the influence of NHPI.

Aerobic oxidation of 1,3,5-triisopropylbenzene using N-hydroxyphthalimide (NHPI) as key catalyst

The first systematic study on the aerobic oxidation of 1,3,5-triisopropylbenzene was examined by the use of N-hydroxyphthalimide (NHPI) as a key catalyst. It was found that 1,3,5-triisopropylbenzene was efficiently oxidized with O 2 in the presence of a catalytic amount of NHPI and azobisisobutyronitrile (AIBN) at 75 °C. Upon treatment of the resulting products with sulfuric acid followed by acetic anhydride led to 5-acetoxy-1,3-diisopropylbenzene and 3,5-diacetoxy-1-isopropylbenzene as major products and a small amount of 1,3,5-triacetoxybenzene. When t-butylperoxypivalate (BPP) was employed as a radical initiator, the oxidation could be achieved in good yield even at 50 °C. This oxidation provides a facile method for preparing phenol derivatives bearing an isopropyl moiety, which can be used as pharmaceutical starting materials.

Development of Catalytic Carbon Radical Generation and Its Application to Organic Synthesis

AbstractFor Abstract see ChemInform Abstract in Full Text.

The First Hydroxysilylation of Alkenes with Triethylsilane under Dioxygen Catalyzed by N‐Hydroxyphthalimide.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Synthesis of ε-caprolactam precursors through the N-hydroxyphthalimide-catalyzed aerobic oxidation of K/A-oil

A methodology for the preparation of e-caprolactam (CL) precursors like 1,1′-peroxydicyclohexylamine (PDHA) and/or cyclohexanone oxime from K/A-oil (a mixture of cyclohexanone and cyclohexanol) has been established by the use of N-hydroxyphthalimide (NHPI) as a key catalyst. Thus, the aerobic oxidation of K/A-oil catalyzed by NHPI followed by treatment with ammonia afforded CL precursors in high selectivities.

Development of Catalytic Carbon Radical Generation and Its Application to Organic Synthesis

Innovative carbon radical generation from hydrocarbons through a catalytic process under mild conditions has been achieved by the use of N-hydroxyphthalimide (NHPI) as a catalyst. This method can be successfully applied to a wide variety of functionalizations of hydrocarbons. Thus, alkanes are converted into alcohols, ketones, carboxylic acids, nitro alkanes and alkyl sulfonic acids through alkyl radicals generated by the action of NHPI. Hydroxysilylation was first performed by the addition of hydrosilanes and oxygen to alkenes bearing electron-withdrawing substituents. A new approach to oxyalkylation based on the concomitant addition of carbon radicals derived from alkanes or alcohols and molecular oxygen to alkenes or alkynes has been described.

Selective catalytic oxidation of cyclohexylbenzene to cyclohexylbenzene-1-hydroperoxide: a coproduct-free route to phenol

A method is described for the highly selective oxidation of cyclohexylbenzene to cyclohexylbenzene-1-hydroperoxide. In the presence of 0.5 mol% N-hydroxyphthalimide (NHPI) and 2 mol% of the hydroperoxide product, without solvent, a selectivity of ca. 98% to the desired product was obtained at 32% conversion. The use of NHPI increases the selectivity for initial H-abstraction from the 1-position, vs the other positions in the cyclohexyl ring, suppresses byproduct formation via transannular hydrogen abstraction and increases the overall rate of reaction.

An efficient nitration of light alkanes and the alkyl side-chain of aromatic compounds with nitrogen dioxide and nitric acid catalyzed by N-hydroxyphthalimide.

Nitration of light alkanes and the alkyl side-chain of aromatic compounds with NO(2) and HNO(3) was successfully achieved by the use of N-hydroxyphthalimide (NHPI) as a catalyst under relatively mild conditions. For example, the nitration of propane with NO(2) catalyzed by NHPI at 100 degrees C for 14 h gave 2-nitropropane in good yield without formation of 1-nitropropane and cleaved products such as nitroethane and nitromethane. Various aliphatic nitroalkanes, which are difficult to prepare by conventional methods, could be selectively obtained by means of the present methodology by using NHPI as the key catalyst. In addition, the side-chain nitration of alkylbenzenes such as toluene was selectively carried out to lead to alpha-nitrotoluene without the ring nitration. The present reaction provides an efficient selective method for the nitration of light alkanes and alkylbenzenes, which has been very difficult to carry out so far.

First Ritter-type reaction of alkylbenzenes using N-hydroxyphthalimide as a key catalyst.

The first Ritter-type reaction of alkylbenzenes with nitriles has been successfully achieved by the use of N-hydroxyphthalimide (NHPI) as a key catalyst. Thus, treatment of ethylbenzene with ammonium hexanitratocerate(IV) (CAN) in the presence of a catalytic amount of NHPI in EtCN under argon produced the corresponding amide in good selectivity.

The radical-chain addition of aldehydes to alkenes by the use of N-hydroxyphthalimide (NHPI) as a polarity-reversal catalyst.

Hydroacylation of simple alkenes with aldehydes via a radical process was successfully achieved by the use of N-hydroxyphthalimide (NHPI) as a polarity-reversal catalyst. Thus, 5-tridecanone was obtained by the reaction of oct-1-ene with pentanal in the presence of small amounts of NHPI and dibenzoyl peroxide (BPO).

Catalytic oxyalkylation of alkenes with alkanes and molecular oxygen via a radical process using N-hydroxyphthalimide.

A novel catalytic method for the radical addition of alkanes and molecular oxygen to electron-deficient alkenes was achieved by the use of N-hydroxyphthalimide (NHPI) combined with a Co species as the catalyst. This reaction is referred to as oxyalkylation of alkenes with alkanes and O(2). For instance, the reaction of 1,3-dimethyladamantane with methyl acrylate under molecular oxygen in the presence of catalytic amounts of NHPI and Co(acac)(3) at 70 degrees C for 16 h gave oxyalkylated products in 91% yield. Other alkenes such as fumarate and acrylonitrile also serve as good acceptors of alkyl radicals and O(2) to afford the corresponding adducts in high yields. The generality of the present reaction was examined between various alkanes and alkenes under dioxygen. The behavior of Co ions during the reaction course was discussed. The present reaction involves (i) an alkyl radical generation via hydrogen abstraction of alkane by phthalimide N-oxyl generated in situ from NHPI and O(2) assisted by Co(II), (ii) the addition of the resulting alkyl radical to an electron-deficient alkene to form an adduct radical, (iii) trapping of the adduct radical by O(2) yielding a hydroperoxide, and (iv) the decomposition of the hydroperoxide by Co ions to form an adduct in which a hydroxy or a carbonyl function is incorporated.

Development of Catalytic Carbon Radical Generation and Its Application to Organic Synthesis

Innovative carbon radical generation from hydrocarbons through a catalytic process under mild conditions has been achieved by the use of N-hydroxyphthalimide (NHPI) as a catalyst. This method can be successfully applied to a wide variety of functionalizations of hydrocarbons. Thus, alkanes are converted into alcohols, ketones, carboxylic acids, nitro alkanes and alkyl sulfonic acids through alkyl radicals generated by the action of NHPI. Hydroxysilylation was first performed by the addition of hydrosilanes and oxygen to alkenes bearing electron-withdrawing substituents. A new approach to oxyalkylation based on the concomitant addition of carbon radicals derived from alkanes or alcohols and molecular oxygen to alkenes or alkynes has been described.

Nitration of alkanes with nitric acid catalyzed by N-hydroxyphthalimide

Catalytic nitration of alkanes with nitric acid was first successfully achieved by the use of N-hydroxyphthalimide (NHPI) under mild conditions; the key to the present nitration was found to be the in situ generation of NO2 and phthalimide N-oxyl radical by the reaction of NHPI with nitric acid.