Selectivity engineering of O-methylation of hydroxybenzenes with dimethyl carbonate using ionic liquid as catalyst

Kabra, Satish K.; Huuhtanen, Mika; Keiski, Riitta L.; Yadav, Ganapati D.

doi:10.1039/c6re00016a

Cited by 24 publications

(8 citation statements)

References 23 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Alkylation of phenols is an important process in the chemical industry and has become even more interesting with the research on biomass derived phenols . An usual approach for alkylation of phenols is by phase‐transfer catalysis, where the counter‐ion plays a key role in the process.…”

Section: Resultsmentioning

confidence: 99%

Counter‐ion and solvent effects in the C‐ and O‐alkylation of the phenoxide ion with allyl chloride

Nogueira

Pliego

2019

J of Physical Organic Chem

View full text Add to dashboard Cite

The alkylation reaction of the phenoxide ion with allyl chloride can take place in the oxygen atom or in the carbons of the aromatic ring in the ortho position. Experimental studies have suggested that solvent effects and ion pairing are important for the regioselectivity. In this work, this reaction has been studied by means of theoretical methods using density functional theory, continuum solvation models, and inclusion of some explicit water molecules. It was found that O-alkylation is the only product in the reaction of free phenoxide ion in the gas phase. Inclusion of the solvent effect induces an activation barrier, and although the effect is more important for O-alkylation, it is not enough to reverse the major O-alkylation reaction path. When the reaction via the ion pair was considered, it was found that attack in the C3 carbon of the allyl chloride in the syn orientation of the leaving chloride ion leads to a stable transition state, with close activation barriers for both O-and C-alkylations.Inclusion of the solvent effect to the ion pair reaction makes both the reaction barriers closer (difference of 0.2 kcal mol −1 ), in excellent agreement with the experimental data. The absolute theoretical free energy barriers also reproduce the experimental barriers with a deviation of 3.5 kcal mol −1 . Thus, theoretical calculations point out that both ion pairing and solvation are critical for controlling reactivity and regioselectivity of this reaction.

show abstract

Section: Resultsmentioning

confidence: 99%

Counter‐ion and solvent effects in the C‐ and O‐alkylation of the phenoxide ion with allyl chloride

Nogueira

Pliego

2019

J of Physical Organic Chem

View full text Add to dashboard Cite

show abstract

“…Recently, vapour-phase selective O-methylation of catechol to synthesize guaiacol, which is an economically and environmentally friendly route for industrial applications, has attracted extensive attention from scientific researchers [16][17][18][19][20]. Methanol is believed to be a very promising candidate for use as a methylation agent for selective O-methylation of catechol due to its low toxicity and low cost.…”

Section: Introductionmentioning

confidence: 99%

One-Pot Synthesis of Al-P-O Catalysts and Their Catalytic Properties for O-Methylation of Catechol and Methanol

Ren

Yue

et al. 2021

Materials

View full text Add to dashboard Cite

A series of Al-P-O catalysts (Al-xP-O) were prepared using a P123-assisted one-pot method at different P/Al molar ratios and used for O-methylation of catechol and methanol. The influences of the P/Al molar ratio and P123 addition on catalyst structure and surface acid-base characteristics were investigated in detail. Increasing the P/Al molar ratio more favored crystalline aluminophosphate. The P123-assisted Al3+ and PO43− are known to be stabilized through weak steric force so that the formation of crystalline aluminophosphate could be inhibited at higher P/Al molar ratios. The results showed that the prepared Al-P-O catalysts possessed appropriate weak acid and weak base sites, which was beneficial to the reaction of catechol and methanol. The Al-1.1P-O catalyst synthesized with the assistance of P123 exhibited superior catalytic performances, with 52.5% catechol conversion and higher guaiacol selectivity of 97.6%.

show abstract

“…A number of researchers have studied the detailed kinetics and mechanism for alkylation of phenol, [ 21–25 ] but very few reports (only two research articles) are available on kinetic study for monoalkylation of HQ. One is reported by Yadav et al, [ 2 ] where reactions were performed at high temperature, above 483 K. Another article published by Bal and co‐workers, [ 1 ] in which vapour phase methylation of HQ was conducted at 673 K temperature and a higher rate for the dialkylation reaction was reported.…”

Section: Introductionmentioning

confidence: 99%

Kinetic study on alkylation of hydroquinone with methanol over SO₃H functionalized Brønsted acidic ionic liquids

Bhongale

Amonkar²,

Joshi

et al. 2021

Can J Chem Eng

View full text Add to dashboard Cite

O‐alkylation of a dihydric phenol (i.e., hydroquinone) with methanol in presence of benzoquinone catalyzed by double SO3H functionalized Brønsted acidic ionic liquids (i.e., 1,3‐disulphonic acid imidazolium hydrogen sulphate, 1,3‐disulphonic acid benzimidazolium hydrogen sulphate, and sulphuric acid) is studied in a batch reactor. The sensitivity of activity and selectivity with reaction time, temperature, speed of agitation, and catalyst loading was examined. The plausible reaction pathways proposed based on the experimental observations and detailed kinetic investigation are performed by assuming a homogeneous reaction phase. The kinetic parameters, such as pre‐exponential factor and activation energy, are estimated for both ionic liquids and sulphuric acid by considering all competitive reactions, and comparative results were presented. An extended form of the Arrhenius equation is used to estimate the kinetic parameters for the reaction which showed curvature in lnk against a 1/T plot. The model prediction with the estimated kinetic parameters is in good agreement with the experimental data, which confirmed the model validity in the experimental operating range. It was found that ionic liquid has a potential application in the synthesis of a selective monoalkylated product of hydroquinone. The kinetic analysis performed is found to be useful in the understanding of process behaviour.

show abstract

Selectivity engineering of O-methylation of hydroxybenzenes with dimethyl carbonate using ionic liquid as catalyst

Abstract: Phenolic ethers are useful commercial entities which have been traditionally produced via polluting routes that could be replaced by benign catalytic processes.

Cited by 24 publications

References 23 publications

Counter‐ion and solvent effects in the C‐ and O‐alkylation of the phenoxide ion with allyl chloride

Counter‐ion and solvent effects in the C‐ and O‐alkylation of the phenoxide ion with allyl chloride

One-Pot Synthesis of Al-P-O Catalysts and Their Catalytic Properties for O-Methylation of Catechol and Methanol

Kinetic study on alkylation of hydroquinone with methanol over SO₃H functionalized Brønsted acidic ionic liquids

Contact Info

Product

Resources

About

Selectivity engineering of O-methylation of hydroxybenzenes with dimethyl carbonate using ionic liquid as catalyst

Abstract: Phenolic ethers are useful commercial entities which have been traditionally produced via polluting routes that could be replaced by benign catalytic processes.

Cited by 24 publications

References 23 publications

Counter‐ion and solvent effects in the C‐ and O‐alkylation of the phenoxide ion with allyl chloride

Counter‐ion and solvent effects in the C‐ and O‐alkylation of the phenoxide ion with allyl chloride

One-Pot Synthesis of Al-P-O Catalysts and Their Catalytic Properties for O-Methylation of Catechol and Methanol

Kinetic study on alkylation of hydroquinone with methanol over SO3H functionalized Brønsted acidic ionic liquids

Contact Info

Product

Resources

About

Kinetic study on alkylation of hydroquinone with methanol over SO₃H functionalized Brønsted acidic ionic liquids