cas 2416-94-6, 2,3,6-Trimethylphenol | Articles data

Articles about 2416-94-6Total 28 be found

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Selective C-C and C-H Bond Activation/Cleavage of Pinene Derivatives: Synthesis of Enantiopure Cyclohexenone Scaffolds and Mechanistic Insights
The continued development of transition-metal-mediated C-C bond activation/cleavage methods would provide even more opportunities to implement novel synthetic strategies. We have explored the Rh(I)-catalyzed C-C activation of cyclobutanols resident in hydroxylated derivatives of pinene, which proceed in a complementary manner to the C-C bond cleavage that we have observed with many traditional electrophilic reagents. Mechanistic and computational studies have provided insight into the role of C-H bond activation in the stereochemical outcome of the Rh-catalyzed C-C bond activation process. Using this new approach, functionalized cyclohexenones that form the cores of natural products, including the spiroindicumides and phomactin A, have been accessed.
Masarwa, Ahmad,Weber, Manuel,Sarpong, Richmond
p. 6327 - 6334
(2015)
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Catalytic activity of a mordenite catalyst in alkylation of xylenols with methanol
The catalytic activity of a palladium-containing mordenite catalyst in alkylation of 2,6-, 2,4-, 2,5-, 2,3-, 3,4-, and 3,5-xylenols with methanol was studied. The main and by-products of catalysis and the activity of the catalyst in synthesis of individual trimethylphenols were determined.
Agaev,Madatzade
p. 683 - 684
(2005)
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OXIDATION OF PSEUDOCUMENE IN ACETIC ACID
The oxidation of pseudocumene in the benzene nucleus can be effected in HOAc solutions by using inorganic oxidizing agents containing oxygen, such as NaNO3, heteropolyacids, O2, Na2S2O8, and H2O2, with Pd(OAc)2 as catalyst.Na2S2O8 and H2O2 are the most ef
Kholdeeva, O. A.,Kozhevnikov, I.V.,Sidel'nikov, V. N.,Utkin, V. A.
(1989)
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Vapor phase methylation of m-Cresol over Ce-impregnated Cd1-xCrxFe2O4 (x = 0, 0.25, 0.50, 0.75 and 1.0) ferrospinels
Cd-Cr ferrospinels prepared by co-precipitation method were impregnated with cerium as promoter. Ce-impregnated ferrospinels were tested for the vapor phase alkylation of m-cresol with methanol. It has been observed that with increase in value of 'x' in C
Kadian, Malvika,Gupta
p. 905 - 907
(2017)
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Substrate substitution effects in the Fries rearrangement of aryl esters over zeolite catalysts
The catalytic transformation of aryl esters to hydroxyacetophenones via Fries rearrangement over solid acids is of interest to avoid the use of corrosive and toxic Lewis and Br?nsted acids traditionally applied. Microporous zeolites are known to catalyze the reaction of simple substrates such as phenyl acetate, but their application to substituted derivatives has received limited attention. To refine structure-activity relationships, here we examine the impact of various parameters including the solvent polarity, water content, acidic properties, and framework type on the reaction scheme in the Fries rearrangement of p-tolyl acetate over common solid acids. The results confirm the importance of providing a high concentration of accessible Br?nsted acid sites, with beta zeolites exhibiting the best performance. Extension of the substrate scope by substituting methyl groups in multiple positions identifies a framework-dependent effect on the rearrangement chemistry and highlights the potential for the transformation of dimethylphenyl acetates. Kinetic studies show that the major competitive path of cleavage of the ester C-O bond usually occurs in parallel to the Fries rearrangement. The possibility of sequentially acylating the resulting phenol depends on the substrate and reaction conditions.
Bonrath, Werner,Létinois, Ulla,Lin, Ronghe,Medlock, Jonathan,Mitchell, Sharon,Netscher, Thomas,Pérez-Ramírez, Javier,Stemmler, René T.
p. 4282 - 4292
(2020/07/30)

Deoxyalkylation of guaiacol using haggite structured V4O6(OH)4
When V2O5 is used for the deoxygenation of guaiacol in methanol, it is reduced in situ to haggite structured V4O6(OH)4. Guaiacol prevents further reduction of the haggite phase in methanol and haggite catalyzes the partial deoxygenation of guaiacol. Haggite is a metastable redox catalyst for the deoxygenation of guaiacol, which follows the reverse Mars-van Krevelen mechanism. In addition, haggite is also a Lewis acid catalyst and catalyzes the alkylation of guaiacol with methanol as the alkylation reagent. The main products of the guaiacol deoxyalkylation are 2,6-dimethylphenol, 2-methoxy-6-methylphenol, 2,4,6-trimethylphenol, 2,3,6-trimethylphenol, 2,3,5,6-tetramethylphenol and 6-methyl-2-tert-butylphenol. Oligomerization takes place during the reaction but it is reversible. When the reaction is performed at 300 °C for 6 h, the 83.5% total selectivity for alkylphenols is achieved with a 99.0% conversion.
Yan, Fei,Wen, Zhe,Wu, Kai,Cui, Kai,Mai, Fuhang,Ma, Zewei,Sang, Yushuai,Bai, Yunfei,Chen, Hong,Li, Yongdan
p. 1922 - 1932
(2019/04/29)

PROCESS FOR PREPARING (POLY)ALKYLATED PHENOLS
The present invention relates to the manufacturing and use of (poly)alkylphenols. They can be prepared from 2-(methoxymethyl)phenols by catalytic reduction in a high efficiency and selectivity.
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Page/Page column 15; 16

(2018/06/12)

Catalyst for synthesis of 2, 3, 6-trimethylphenol and preparation method thereof
The invention discloses a catalyst for synthesis of 2, 3, 6-trimethylphenol and a preparation method thereof, and relates to a catalyst and a preparation method thereof. The catalyst for the synthesisof the 2,3,6-trimethylphenol from m-cresol comprises Fe2O3, SiO2 and CuO. In the preparation, Fe(NO3)3.9H2O is dissolved in deionized water, then Na2SiO3.9H2O and Cu(NO3)2.3H2O are added in sequence,and then dissolved to obtain a mixture A; ammonia water is added to the mixture A, stirred, aged, cooled to room temperature, and filtered by suction, and a filter cake is dried and calcined to obtain the catalyst for the synthesis of the 2,3,6-trimethylphenol from the m-cresol. The catalyst is free of precious metals and toxic heavy metals, low in cost, environmentally friendly, simple in preparation method, good in catalytic activity and high in selectivity, m-cresol conversion rate can reach 100%, and selectivity of the 2,3,6-trimethylphenol can reach 97.9%.
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Paragraph 0017; 0018; 0019; 0020; 0023

(2018/09/11)

An Enzymatic Route to α-Tocopherol Synthons: Aromatic Hydroxylation of Pseudocumene and Mesitylene with P450 BM3
Aromatic hydroxylation of pseudocumene (1 a) and mesitylene (1 b) with P450 BM3 yields key phenolic building blocks for α-tocopherol synthesis. The P450 BM3 wild-type (WT) catalyzed selective aromatic hydroxylation of 1 b (94 %), whereas 1 a was hydroxylated to a large extent on benzylic positions (46–64 %). Site-saturation mutagenesis generated a new P450 BM3 mutant, herein named “variant M3” (R47S, Y51W, A330F, I401M), with significantly increased coupling efficiency (3- to 8-fold) and activity (75- to 230-fold) for the conversion of 1 a and 1 b. Additional π–π interactions introduced by mutation A330F improved not only productivity and coupling efficiency, but also selectivity toward aromatic hydroxylation of 1 a (61 to 75 %). Under continuous nicotinamide adenine dinucleotide phosphate recycling, the novel P450 BM3 variant M3 was able to produce the key tocopherol precursor trimethylhydroquinone (3 a; 35 % selectivity; 0.18 mg mL?1) directly from 1 a. In the case of 1 b, overoxidation leads to dearomatization and the formation of a valuable p-quinol synthon that can directly serve as an educt for the synthesis of 3 a. Detailed product pattern analysis, substrate docking, and mechanistic considerations support the hypothesis that 1 a binds in an inverted orientation in the active site of P450 BM3 WT, relative to P450 BM3 variant M3, to allow this change in chemoselectivity. This study provides an enzymatic route to key phenolic synthons for α-tocopherols and the first catalytic and mechanistic insights into direct aromatic hydroxylation and dearomatization of trimethylbenzenes with O2.
Dennig, Alexander,Weingartner, Alexandra Maria,Kardashliev, Tsvetan,Müller, Christina Andrea,Tassano, Erika,Schürmann, Martin,Ruff, Anna Jo?lle,Schwaneberg, Ulrich
p. 17981 - 17991
(2017/11/29)

INTERMOLECULAR REACTION OF PROPARGYL ETHERS WITH DIMETHYLFURAN IN THE PRESENCE OF GOLD(I) COMPLEXES
The present invention relates to a method of preparing ortho substituted phenols from 2,5-dimethylfuran and propargyl ethers in the presence of a gold(I) complex. It is particularly advantageous to use 2,5-dimethylfuran as this offers an ecological beneficial synthesis of said ortho substituted phenols.
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Paragraph 23; 24

(2017/07/14)

Construction of Acid–Base Synergetic Sites on Mg-bearing BEA Zeolites Triggers the Unexpected Low-Temperature Alkylation of Phenol
Novel Mg-bearing BEA zeolites are synthesized to simultaneously endow significantly enhanced basicity without compromising acidity over the zeolite framework. Serving as efficient solid acid–base bifunctional catalysts, they achieve the liquid-phase selective methylation of phenol with methanol to produce o- and p-cresol (o/p=2) under mild conditions. The method is readily extendable to the alkylation of phenols with various alcohols. Stereo- and regioselectivity (>95 % for p-product) was attained on the alkylation of phenol with bulky tert-butyl alcohol, rendering the first acid–base cooperative shape-selective catalysis relying on the basicity of zeolites. A preliminary mechanistic analysis reveals that the remarkable activity and shape-selectivity come from the superior special acidic–basic synergetic catalytic sites on the uniform microporous channels of the BEA zeolite.
Xie, Jingyan,Zhuang, Wenxia,Zhang, Wei,Yan, Ning,Zhou, Yu,Wang, Jun
p. 1076 - 1083
(2017/03/27)

A 2, 3, 6-trimethyl phenol preparation method
The invention discloses a preparation method of 2, 3, 6-trimethylphenol. The method comprises the following step: in the presence of a ferric oxide catalyst, carrying out gas-phase reaction on a raw material phenol and methanol, water and nitrogen in a fixed bed reactor to synthesize 2, 3, 6-trimethylphenol. The catalyst used in the invention has the characteristics of being high in activity, long in service life, low in cost and the like and has the advantages of being simple in reaction synthetic process, low in temperature, mild in condition, high in raw material conversion rate, high in product selectivity and the like.
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Paragraph 0026; 0027

(2017/04/03)

PROCESS OF PRODUCTION OF 2,3,6-TRIMETHYLPHENOL
The present invention relates to a new method to produce 2,3,6-trimethylphenol (2,3,6-TMP).
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Page/Page column 16-17

(2015/08/06)

Orthoalkylation catalyst for phenol and process for producing orthoalkylated phenol with use thereof
The orthoalkylation catalyst for phenols of the invention is one produced by calcining a catalyst precursor comprising basic magnesium carbonate (a) and magnesium oxide (b) optionally together with manganese oxalate (c), the basic magnesium carbonate (a) and magnesium oxide (b) being mixed together at a weight ratio ((a)/(b)) of 20/80 to 80/20. The process for producing an orthoalkylated phenol according to the invention comprises performing a vapor phase reaction of a phenol with an alkyl alcohol in the presence of the above orthoalkylation catalyst so that an orthoalkylated phenol is obtained.The invention enables obtaining an orthoalkylation catalyst for phenols which has high activity and high selectivity, has long catalytic life and exhibits more stable catalytic life than those of conventional orthoalkylation catalysts for phenols. Moreover, by virtue of the use of the catalyst capable of exerting these effects, there can be obtained a process for producing an orthoalkylated phenol which ensures prolonged and constant catalyst regeneration cycle.
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Page/Page column 7-10

(2008/06/13)

Continuous chemoselective methylation of m-cresol and phenol with supercritical methanol over solid acid and base metal oxide catalysts
The chemoselective methylation of m-cresol and phenol with supercritical methanol (scCH3OH) promoted by metal oxide catalysts (MgO, ZrO 2, Cs-P-Si and Fe-V/SiO2) was investigated in a continuous flow fixed bed reactor. The use of scCH3OH as a carrier medium led to a significant change in the product selectivity compared to that attained in the gas phase reaction, and caused a marked suppression of the degradation of CH3OH during the reaction, resulting in an improvement in the catalyst lifetime. The chemoselective outcome of the reaction was highly influenced by the acid-base character on the solid catalysts examined under supercritical conditions.
Oku, Tomoharu,Arita, Yoshitaka,Ikariya, Takao
p. 1553 - 1557
(2007/10/03)

Ortho-alkylation of phenol with methanol using Pb-Cr promoted magnesium oxide catalysts
In this study, Pb-Cr promoted magnesium oxide catalysts were used to catalyze the ortho-alkylation of phenol in the presence of excess methanol. The Cr/MgO catalyst exhibited a high conversion of phenol and a relatively high selectivity for the ortho-alkylation of phenol. The catalytic activity and the stability of Cr/MgO were improved by the addition of a fairly small amount of Pb. The Pb-Cr/MgO catalyst showed specificity for the ortho-alkylation of phenol, which was proved by a series of phenol derivative reactions with methanol.
Ke, Jyh-Harng,Zena, Jyh-Myng,Wang, Fey-Long
p. 1407 - 1410
(2007/10/03)

Process for functionalising a phenolic compound carrying an electron-donating group
The invention concerns a method for functionalizing a phenolic compound bearing an electron-donor group, in said group para position, inter alia a method for the amidoalkylation of a phenolic compound bearing an electron-donor group, and more particularly, a phenolic compound bearing an electron-donor group preferably, in the hydroxyl group ortho position. The method for functionalizing in para position with respect to an electron-donor group carried by a phenolic compound is characterised in that the phenolic compound bearing an electron-donor group is subjected to the following steps: a first step which consists of protecting the hydroxyl group in the form of a sulphonic ester function; a second step which consists in reacting the protected phenolic compound with an electrophilic reagent; optionally, a third step deprotecting the hydroxyl group.
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(2008/06/13)

ORTHO-METHYLATION OF PHENOLS WITH ETHYL(IODOMETHYL)ZINC
The regioselective ortho-methylation of phenols by in situ generated ethyl(iodomethyl)zinc via an internal alkylation process is described.
Lehnert, Erich K.,Sawyer, J. Scott,Macdonald, Timothy L.
p. 5215 - 5218
(2007/10/02)

Process for producing alkylphenols
There is disclosed a process for producing an alkylphenol comprising reacting a phenol with an aldehyde and hydrogen in the presence of (a) an alkaline or alkaline earth metal catalyst selected from a hydroxide of an alkaline metal, hydroxide of an alkaline earth metal, a carbonate of an alkaline metal, and a hydrogencarbonate of an alkaline metal and (b) a hydrogenation catalyst. By the use of the process, the alkylphenols can be produced in good yield in one stage method.
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(2008/06/13)

A quantitative examination of the photoisomerization of some protonated phenols
The photoisomerization of a series of protonated, methyl substituted phenols to protonated bicyclohexenones has been examined.These reactions, which were carried out in CF3SO3H as a strong acid solvent at ambient temperatures, provide a convenient route to a variety of bicyclohexenones.The quantum yields for these photoisomerizations vary from 0.018 for protonated 3,5-dimethylphenol to 0.65 for protonated 2,6-dimethylphenol.This variation in efficiency can be understood in terms of a competition between ring opening, to regenerate the starting phenol, or cyclopropyl migration, to give product, of aninitially formed intermediate.
Childs, Ronald F.,George, Baha E.
p. 1343 - 1349
(2007/10/02)

Thermal isomerizations of protonated bicyclohexenones
The thermal isomerizations of a wide range of protonated methyl substituted bicyclohex-3-en-2-ones to protonated phenols has been examined using triflic acid as a strong acid solvent.The rate constants and activation energies of these isomerization has been determined.The barriers to the isomerizations were shown to be dependent on the number and position of the methyl substituents.The results show that three different mechanisms are needed to account for these isomerizations, two of which involve a preliminary circumambulatory rearrangement prior to ring opening and the other process involving a direct ring opening of the initial protonated bicyclohexenone to give an intermediate meta-protonated phenol.
Childs, Ronald F.,George, Baha E.
p. 1350 - 1354
(2007/10/02)

Rate and Equilibrium Studies of the Reaction of Oxyanions with 2-Phenyloxazol-5(4H)-one
Equilibrium constants for the reaction of phenoxide ions with 2-phenyloxazol-5(4H)-one at 25 deg C and 1M ionic strength obey a Broensted relationship (log kOH/kArO = log K' = -173pKArOH - 15.81) and are not subject to steric effects from ortho-substituents.Both forward and reverse rate parameters exhibit steric effects, and the Broensted equations for meta- and para-substituted species are log kOH = -0.81 pKArOH + 9.75, and log kArO = 0.95pKArOH - 6.40.There is no break in the Broensted line in the region of pKArOH 5-11, consistent with a single transition-state.An upward deviation exists for oxyanions with low basicity (pKXOH 5); one of these oxyanions, betaine, has a solvent deuterium oxide isotope effect for its reaction with the oxazolone greater than 2, consistent with a general base mechanism for attack for these species.The results for nucleophilic attack of phenolate anions are in agreement with a concerted displacement at the carbonyl group.
Chrystiuk, Edwin,Jusoh, Adelina,Santafianos, Dino,Williams, Andrew
p. 163 - 168
(2007/10/02)

The use of homogeneous and heterogeneous Lewis acids to catalyse the photoisomerizations of phenols
The reaction of methyl substituted phenols with CH2Cl2 solutions of Al2Br6 leads to the formation of two types of complexes.In both of these the aluminum is bound to the oxygen atom of the phenol but they differ in that the OH proton can either remain on oxygen, oxonium complex, or migrate to one, usually the para, ring carbon, keto complex.The equilibrium position between the two types of complex depends on the position of the methyl groups.Irradiation of a complex of the keto type leads initially to the formation of a complexed bicyclohexenone and subsequently to the formation of an isomeric complexed phenol.Only in the case of the tetramethylphenols is the yield of the bicyclic ketone high enough to warrant the use of this photoisomerization as a preparative procedure, although the technique can be used to isomerize a range of phenols to their 4-substituted isomers.The photoisomerizations are not restricted to the use of a homogeneus Lewis acid such as Al2Br6 but heterogeneus aluminosilicates can also be used.The adsorption of 2,3,5,6-tetramethylphenol, 1h, on an aluminosilicate was monitored quantitatively and it was shown that a monolayer was formed in which the phenol was at least partially present in the keto form.Irradiation of 1h in the presence of stirred slurries of the aluminosilicate led to the formation of 2,3,4,6-tetramethylphenol.No bicyclic ketones were present in the contacting solution but traces were detected on the catalyst when the irradiations were carried out on adsorbed material in the absence of a solvent.In the case of heterogeneous acids, the selectivity in the adsorption of the starting phenol and the photoproducts is important in determining the composition of the final mixture.
Chadda, Satish K.,Childs, Ronald F.
p. 3449 - 3455
(2007/10/02)

Thermolysis of gem-dimethyl-2-cyclohexenones. Evidence for sigmatropic methyl shifts
The vapour phase thermolyses at 400 deg C of three gem-dimethylated 2-cyclohexenones 1, 2, and 3 were studied to determine the effect of blocking the direct conversion of these substrates to aromatic systems.In all three reactions it is proposed the major pathway taken was enolization followed by elimination of methane to yield a substituted phenol.This elimination reaction proceeded more readily with 2 than with either 1 or 3, and HMO calculations which are consistent with this order of reactivity are presented.A general mechanistic scheme is proposed to account for the products formed and it is necessary to include a sigmatropic methyl shift to explain the formation of at least one product in each thermolysis.
Lange, G. L.,Nye, M. J.,Pereira, V. A.,Stratton, V.,Yurkevich, T.
p. 1903 - 1907
(2007/10/02)

Conversion of alkyl and aryl hydroxy compounds producing aldehyde, alcohol and ketone using manganese oxide/nickel oxide/magnesium oxide catalysts
Alkyl and aryl hydroxy compounds are converted to aldehydes, alcohols, and ketones in the presence of hydrogen using a catalyst comprised of the oxides of manganese, nickel and magnesium.
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(2008/06/13)

Production of 2,3,6-trimethylphenol
A process for the production of 2,3,6-trimethylphenol in which diethyl ketone is reacted in the presence of a basic reagent with crotonaldehyde or methyl vinyl ketone (or a compound which in the presence of a basic reagent is converted into crotonaldehyde or methyl vinyl ketone) and the 2,5,6-trimethyl-2-cyclohexen-1-one or 2,3,6-trimethyl-2-cyclohexen-1-one formed is dehydrogenated.
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(2008/06/13)

Preparation of 2,3,6-tri-lower alkyl phenols
Preparation of 2,3,6-tri-lower alkyl phenols from the condensation product of an α,β-unsaturated aldehyde with a dilower alkyl ketone.
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(2008/06/13)

Preparation of ortho-alkylated phenols
There are provided alkylation catalysts comprising magnesium oxide mixed with and bonded by manganese oxides. These are used in processes for the vapor phase ortho-alkylation of phenols with an alcohol. The present catalysts are advantageous in that they provide a substantially increased total useful life, a reduced induction period for maximum reaction selectivity, elimination of catalyst losses in comparison with the powders or weakly sintered composites of the prior art and increased selectivity for ortho-substitution. Treatment of the new catalysts with methanol vapor before use enhances their activity in converting phenols to 2,6-xylenol and results in a significant increase in production rate.
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(2008/06/13)