- Non-catalytic and selective alkylation of phenol with propan-2-ol in supercritical water
-
Phenol can be alkylated with propan-2-ol without catalyst in supercritical water at 673 K with mainly ortho substituted alkylphenols being obtained and alkylation reaction rate increasing with increasing water density.
- Sato,Sekiguchi,Adschiri,Arai
-
-
Read Online
- Selective synthesis of propofol (2,6-diisopropylphenol), an intravenous anesthetic drug, by isopropylation of phenol over H-beta and H-mordenite
-
Propofol (2,6-diisopropylphenol/DIPP) is the world's most widely used intravenous general anesthetic and is typically synthesized by isopropylation of phenol over an acid catalyst. It is highly difficult to stabilize bio-oil containing phenolic compounds. The isopropylation of this phenol (a model compound representing species in bio-oils) is one of the options to stabilize the bio-oil and convert it into valuable products. Probably for the first time, H-beta- and H-mordenite-catalysed vapour phase isopropylation of phenol with isopropyl alcohol (IPA) was studied to selectively synthesize DIPP. The optimization of various operating parameters such as molar ratio (phenol:IPA), weight hourly space velocity (WHSV), reaction temperature and time on stream were performed. H-beta (94% phenol conv. and 56% DIPP sel.) was found to be a potential and more active catalyst than H-mordenite (68% phenol conv. and 43% DIPP sel.) at optimized process parameters. A kinetic model is proposed to probe the intricate reaction kinetics and validated (R2 > 0.98) by the experimental results. H-beta catalyst was observed to be stable for more than 25 h with 94% phenol conversion and 56% selectivity towards DIPP at optimized process parameters. The phenol conversion and DIPP selectivity obtained in the present study are higher than those reported so far. The activation energy obtained for isopropylation of phenol with IPA over H-beta is calculated to be 25.39 kJ mol-1. the Partner Organisations 2014.
- Nandiwale, Kakasaheb Y.,Bokade, Vijay V.
-
-
Read Online
- Synthesis and catalytic performance of HMCM-49/MCM-41 composite molecular sieve for alkylation of phenol with isopropanol
-
HMCM-49/MCM-41 composite molecular sieve was synthesized with hydrothermal method. The physicochemical properties of the composite were characterized by using XRD, FT-IR, SEM, N2 isothermal adsorption-desorption and NH3-TPD. Results of different characterizations indicated that the synthesized composite molecular sieve possessed the characteristics of both HMCM-49 and MCM-41. XRD and N2 isothermal adsorption-desorption revealed that it has both micropores and mesopores, a larger surface area than that of HMCM-49, NH3-TPD and pyridine adsorbed FT-IR revealed that the strong acidic sites that caused side reaction in HMCM-49 are deactivated in the composite molecular sieve of HMCM-49/MCM-41. When applied to the alkylation of phenol with isopropanol, the HMCM-49/MCM-41 composite molecular sieve exhibit an enhanced catalytic performance with significant enhancement in p-isopropylphenol and o-isopropylphenol selectivity, which can be ascribed to the composite characteristics of HMCM-49 and MCM-41. This kind of material will has widely industrial application in preparation of alkyl-phenol.
- Wei, Liguo,Wang, Dong,Dong, Yongli,Song, Weina,Liu, Xiaoxu,Song, Kunyao
-
-
Read Online
- Catalytic performance of Al-MCM-48 molecular sieves for isopropylation of phenol with isopropyl acetate
-
Al-MCM-48 molecular sieves (Si/Al molar ratios = 25, 50, 75, and 100) were synthesized hydrothermally using cetyltrimethylammonium bromide as the structure directing template. The orderly arrangement of mesopores was evident from the low angle X-ray diffr
- Venkatachalam, Kandan,Visuvamithiran, Pitchai,Sundaravel, Balachandran,Palanichamy, Muthiapillai,Murugesan, Velayutham
-
-
Read Online
- A mild and practical method for deprotection of aryl methyl/benzyl/allyl ethers with HPPh2andtBuOK
-
A general method for the demethylation, debenzylation, and deallylation of aryl ethers using HPPh2andtBuOK is reported. The reaction features mild and metal-free reaction conditions, broad substrate scope, good functional group compatibility, and high chemical selectivity towards aryl ethers over aliphatic structures. Notably, this approach is competent to selectively deprotect the allyl or benzyl group, making it a general and practical method in organic synthesis.
- Pan, Wenjing,Li, Chenchen,Zhu, Haoyin,Li, Fangfang,Li, Tao,Zhao, Wanxiang
-
p. 7633 - 7640
(2021/09/22)
-
- Aryl phenol compound as well as synthesis method and application thereof
-
The invention discloses a synthesis method of an aryl phenol compound shown as a formula (3). All systems are carried out in an air or nitrogen atmosphere, and visible light is utilized to excite a photosensitizer for catalyzation. In a reaction solvent, ArNR1R2 as shown in a formula (1) and water as shown in a formula (2) are used as reaction raw materials and react under the auxiliary action of acid to obtain the aryl phenol compound as shown in a formula (3). The ArNR1R2 in the formula (1) can be primary amine and tertiary amine, can also be steroid and amino acid derivatives, and can also be drugs or derivatives of propofol, paracetamol, ibuprofen, oxaprozin, indomethacin and the like. The synthesis method has the advantages of cheap and easily available raw materials, simple reaction operation, mild reaction conditions, high reaction yield and good compatibility of substrate functional groups. The fluid reaction not only can realize amplification of basic chemicals, but also can realize amplification of fine chemicals, such as synthesis of drugs propofol and paracetamol. The invention has wide application prospect and use value.
- -
-
Paragraph 0116-0120
(2021/05/12)
-
- Continuous flow synthesis of propofol
-
Herein, we report a continuous flow process for the synthesis of 2,6-diisopropylphenol— also known as Propofol—a short-acting intravenous anesthesia, widely used in intensive care medicine to provide sedation and hypnosis. The synthesis is based on a two-step procedure: a double Friedel–Crafts alkylation followed by a decarboxylation step, both under continuous flow.
- Jubault, Philippe,Legros, Julien,Mougeot, Romain,Poisson, Thomas
-
supporting information
(2021/12/02)
-
- SIMPLE MANUFACTURING AND PURIFICATION TECHNOLOGY FOR HIGH PURITY PROPOFOL
-
A process for manufacturing Pure Propofol with a purity of more than 99.90% is disclosed, said process comprising dissolving Crude Propofol in a solvent in which it is soluble to form a solution, treating the solution with aqueous alkali to form an aqueous alkali layer and a solvent layer, separating the aqueous alkali layer from the solvent layer using a phase separation technique, distilling off the solvent from the solvent layer, and distilling a residue of the solvent containing Propofol using steam or boiling water in a presence of dilute alkali and antioxidant like metabisulfite, under normal pressure or mild vacuum.
- -
-
Paragraph 0033; 0036; 0043-0045
(2021/08/14)
-
- PROCESS FOR THE PREPARATION OF PROPOFOL
-
The present provides a simple, convenient and time-efficient process for the preparation of propofol. Particularly, the present invention provides an improved process for the preparation of propofol using a heterocyclic base for the decarboxylation reaction. The present invention provides a time-efficient process for the preparation of propofol with high yield and purity.
- -
-
Page/Page column 11-12
(2021/10/02)
-
- Guaiacol demethoxylation catalyzed by Re2O7 in ethanol
-
Re2O7 is used to convert guaiacol in alcohols at 280–320 °C. In ethanol, guaiacol is deoxygenated and alkylated, and the major products are phenol and alkylphenols (including ethylphenol, diethylphenol, diisopropylphenol, di-tert-butylphenol and 2,6-di-tert-butyl-4-ethylphenol), accounting for 97 mol% of all products after 6 hour reaction at 320 °C. Both catechol and phenol are the intermediates of guaiacol demethoxylation. Among the substituents, ethyl is directly provided by ethanol while isopropyl and tert-butyl are formed by the addition of methyl to ethyl step by step. In addition, Re2O7 has negligible activity for the saturation of benzene ring so it does not cause considerable over-consumption of reductant. The actual catalyst for guaiacol demethoxylation is likely a ReIV?VI species.
- Yan, Fei,Sang, Yushuai,Bai, Yunfei,Wu, Kai,Cui, Kai,Wen, Zhe,Mai, Fuhang,Ma, Zewei,Yu, Linhao,Chen, Hong,Li, Yongdan
-
p. 231 - 237
(2019/08/12)
-
- Highly selective conversion of guaiacol to: Tert -butylphenols in supercritical ethanol over a H2WO4 catalyst
-
The conversion of guaiacol is examined at 300 °C in supercritical ethanol over a H2WO4 catalyst. Guaiacol is consumed completely, meanwhile, 16.7% aromatic ethers and 80.0% alkylphenols are obtained. Interestingly, tert-butylphenols are produced mainly with a high selectivity of 71.8%, and the overall selectivity of 2,6-di-tert-butylphenol and 2,6-di-tert-butyl-4-ethylphenol is as high as 63.7%. The experimental results indicate that catechol and 2-ethoxyphenol are the intermediates. Meanwhile, the WO3 sites play an important role in the conversion of guaiacol and the Br?nsted acid sites on H2WO4 enhance the conversion and favour a high selectivity of the tert-butylphenols. The recycling tests show that the carbon deposition on the catalyst surface, the dehydration and partial reduction of the catalyst itself are responsible for the decay of the H2WO4 catalyst. Finally, the possible reaction pathways proposed involve the transetherification process and the alkylation process during guaiacol conversion.
- Mai, Fuhang,Cui, Kai,Wen, Zhe,Wu, Kai,Yan, Fei,Chen, Mengmeng,Chen, Hong,Li, Yongdan
-
p. 2764 - 2771
(2019/02/01)
-
- Synthesis of phenols and aryl silyl ethers via arylation of complementary hydroxide surrogates
-
Two transition-metal-free methods to access substituted phenols via the arylation of silanols or hydrogen peroxide with diaryliodonium salts are presented. The complementary reactivity of the two nucleophiles allows synthesis of a broad range of phenols without competing aryne formation, as illustrated by the synthesis of the anesthetic Propofol. Furthermore, silyl-protected phenols can easily be obtained, which are suitable for further transformations.
- Reitti, Marcus,Gurubrahamam, Ramani,Walther, Melanie,Lindstedt, Erik,Olofsson, Berit
-
supporting information
p. 1785 - 1788
(2018/04/14)
-
- Method for preparing hydrocarbyl phenol by catalytic conversion of phenolic compound in presence of molybdenum-based catalyst
-
The invention discloses a method for preparing hydrocarbyl phenol by catalytic conversion of a phenolic compound in the presence of a molybdenum-based catalyst. The method comprises mixing a phenoliccompound, a molybdenum-based catalyst and a reaction solvent, adding the mixture into a sealed reactor, feeding gas into the reactor, heating the mixture to 150-350 DEG C, carrying out stirring for areaction for 0.5-2h, then filtering to remove a solid catalyst and carrying out rotary evaporateion to obtain a liquid product. The phenolic compound has a wide source, a cost is low, product alkyl phenol selectivity is high, an added value is high, alcohol or an alcohol-water mixture is used as a reaction solvent, environmental friendliness is realized, pollution is avoided, any inorganic acids and alkalis are avoided in the reaction process, the common environmental pollution problems in the biomass processing technology are solved, the reaction conditions are mild, the process can be carried out at a low temperature, high-efficiency conversion of the reactants can be realized without consuming hydrogen gas and the method is suitable for large-scale industrial trial production.
- -
-
Paragraph 0047; 0070
(2018/04/02)
-
- COMPOUNDS AND COMPOSITIONS FOR TREATING CONDITIONS ASSOCIATED WITH NLRP ACTIVITY
-
In one aspect, compounds of Formulae (I) and (II), or pharmaceutically acceptable salts thereof, are featured; Formula (I), Formula (II) or a pharmaceutically acceptable salt thereof, wherein the variables shown in Formulae (I) and (II) can be as defined anywhere herein.
- -
-
Page/Page column 206; 207
(2017/11/15)
-
- A Propofol preparation method
-
The invention provides a preparation method of propofol, which includes following steps: (1) performing Friedel-crafts reaction to p-nitrophenol and isopropanol or 2-halogenated propane under catalysis of an acid to prepare a compound I; (2) performing acylation protection to the compound I to prepare a compound II; (3) performing a reduction reaction to the compound II to prepare a compound III; (4) performing a diazo-reaction to the compound III to prepare a compound IV; and (5) under a weak reducing agent condition, performing a decomposition reaction to the compound IV and meanwhile carrying out hydrolysis under an alkaline condition to obtain the propofol V. The raw materials of the preparation method are easy to obtain. The preparation method is simple in process and is high in yield.
- -
-
-
- A process for preparing high-purity Propofol new method
-
The invention provides a synthetic method for preparing a high-purity anesthetic, i.e., propofol (I). According to the method, the problem of difficulty in removing a large quantity of impurities with similar structures produced in the conventional preparation method is solved, and the emission of phenol pollutants is reduced.
- -
-
Paragraph 0025; 0026
(2017/06/08)
-
- Preparation method for high-purity propofol
-
The invention provides a preparation method for high-purity propofol. The preparation method includes the following steps that S1, under the strong base catalysis condition, a compound shown in the general formula (1) is heated and conducts the decarboxylic reaction in solvent, and a solution system containing the propofol is obtained after acid regulation; and S2, after extraction and alkali washing are conducted on the solution system containing the propofol, the high-purity propofol is obtained through reduced pressure distillation. The invention belongs to the technical field of medicine. The preparation method is wide in raw material source, low in cost, gentle in reaction condition, few in product impurity type and high in product quality, purity is higher than 99.0%, and the requirements for raw material medicine can be met.
- -
-
Paragraph 0047; 0048; 0049; 0050
(2017/05/02)
-
- Preparation method of propofol and structural analogues of propofol
-
The invention relates to a preparation method of propofol and structural analogues of propofol. The preparation method comprises the steps as follows: preparing an intermediate from p-hydroxybenzoic acid and alkyl alcohol as raw materials under the action of a solid acid catalyst, and then preparing a target product by a decarboxylase reaction. The preparation method has the characteristics of being green in synthesis, realizing biotransformation, causing little pollution, producing few by-products and the like, and is suitable for industrial production; the purity of the prepared products such as propofol is 99.6% or higher, which meets various medicinal standards.
- -
-
Paragraph 0094
(2017/08/28)
-
- Selective catalytic conversion of guaiacol to phenols over a molybdenum carbide catalyst
-
An activated carbon supported α-molybdenum carbide catalyst (α-MoC1-x/AC) showed remarkable activity in the selective deoxygenation of guaiacol to substituted mono-phenols in low carbon number alcohol solvents. Combined selectivities of up to 85% for phenol and alkylphenols were obtained at 340°C for α-MoC1-x/AC at 87% conversion in supercritical ethanol. The reaction occurs via consecutive demethylation followed by a dehydroxylation route instead of a direct demethoxygenation pathway.
- Ma, Rui,Cui, Kai,Yang, Le,Ma, Xiaolei,Li, Yongdan
-
supporting information
p. 10299 - 10301
(2015/06/25)
-
- Benzoquinone-promoted aerobic oxidative hydroxylation of arylboronic acids in water
-
A general and efficient aerobic oxidative hydroxylation of arylboronic acids promoted by benzoquinone in water was realized, and provided phenols in 72-95% yields for 20 examples. The main advantages of this protocol are the use of water as solvent in the presence of a catalytic amount of benzoquinone, and metal-free conditions. Georg Thieme Verlag KG Stuttgart · New York.
- Cheng, Guolin,Zeng, Xiaobao,Cui, Xiuling
-
p. 295 - 300
(2014/02/14)
-
- Commercial manufacturing of propofol: Simplifying the isolation process and control on related substances
-
A commercially viable manufacturing process for propofol (1) is described. The process avoids acid-base neutralization events during isolation of intermediate, 2,6-di-isopropylbenzoic acid (3) and crude propofol, and thus simplifies the synthesis on industrial scale to a considerable extent. Syntheses of five impurities/related substances (USP and EP) are also described.
- Pramanik, Chinmoy,Kotharkar, Sandeep,Patil, Pradip,Gotrane, Dinkar,More, Yogesh,Borhade, Ajit,Chaugule, Balaji,Khaladkar, Tushar,Neelakandan,Chaudhari, Ashok,Kulkarni, Mukund G.,Tripathy, Narendra K.,Gurjar, Mukund K.
-
p. 152 - 156
(2014/05/20)
-
- Selective oxidative homo-and cross-coupling of phenols with aerobic catalysts
-
Simple catalysts that use atom-economical oxygen as the terminal oxidant to accomplish selective ortho-ortho, ortho-para, or para-para homo-couplings of phenols are described. In addition, chromium salen catalysts have been discovered as uniquely effective in the cross-coupling of different phenols with high chemo-and regioselectivity.
- Lee, Young Eun,Cao, Trung,Torruellas, Carilyn,Kozlowski, Marisa C.
-
supporting information
p. 6782 - 6785
(2014/06/09)
-
- Synthesis of aryl sulfonamides via palladium-catalyzed chlorosulfonylation of arylboronic acids
-
A palladium-catalyzed method for the preparation of sulfonamides is described. The process exhibits significant functional group tolerance and allows for the preparation of a number of arylsulfonyl chlorides and sulfonamides under mild conditions.
- Debergh, J. Robb,Niljianskul, Nootaree,Buchwald, Stephen L.
-
p. 10638 - 10641
(2013/08/23)
-
- PHENOL C-ALKYLATION PROCESS
-
A method for obtaining high purity 2, 6-diisopropylphenol comprises alkylating 4- hydroxybenzoic acid in presence of an acid followed by basification and decarboxylating 4- hydroxy-3, 5-diisopropylbenzoic acid in presence of high boiling solvents and a catalyst at high temperature.
- -
-
Page/Page column 6
(2013/03/26)
-
- Process for the purification of 2,6-diisopropyl phenol
-
The present invention relates to a novel process for purifying 2,6-diisopropyl phenol (propofol). More particularly, the present invention relates to chlorinating technical grade propofol into a 4-chloropropofol followed by hydrogenating said 4-chloropropofol into a pure propofol.
- -
-
Page/Page column 4
(2012/12/13)
-
- PROCESS FOR THE PURIFICATION OF 2,6-DIISOPROPYL PHENOL
-
The present invention relates to a novel process for purifying 2,6-diisopropy! phenol (propofol). More particularly, the present invention relates to chlorinating technical grade propofol into a 4-chloropropofol followed by hydrogenating said 4-chloropropofol into a pure propofol.
- -
-
Page/Page column 4; 7-8
(2012/12/13)
-
- PROCESS FOR PREPARING EXTRA PURE 2, 6-DIISOPROPYL PHENOL
-
Disclosed herein is a process for the preparation of highly pure 2,6-diisopropyl phenol (Formula I), which comprises reacting p-hydroxy benzoic acid (Formula II) with an alkylating agent in presence of aq. mineral acid followed by basification and subsequent washings to yield 4-hydroxy-3,5-diisopropylbenzoic acid (Formula III) free of dimer impurity, 4, 4''-oxydibenzoic acid of Formula IV, ether impurity 3,5-di(propan-2-yl)-4- (propan-2-yloxy)benzoic acid of Formula V and the monoalkylated impurity 4-hydroxy- 3-(propan-2-yl) benzoic acid of Formula VI; and decarboxylating 4- hydroxy-3,5- diisopropylbenzoic acid (Formula III) in presence of high boiling solvent and sodium hydroxide as a catalyst at high temperature to yield 2, 6-diisopropyl phenol substantially free of ether impurity 1,3-di(propan-2-yl)-2-(propan-2-yloxy)benzene of Formula VII and monoalkylated phenol impurity 2-(propan-2-yl) phenol of Formula VIII. Propofol prepared by the process of the present invention is suitable for pharmaceutical use.
- -
-
Page/Page column 8-9
(2012/01/13)
-
- Microwave-assisted demethylation of methyl aryl ethers using an ionic liquid
-
An efficient demethylation of methyl aryl ethers using an ionic liquid, 1-n-butyl-3-methylimidazolium bromide ([bmim][Br]) has been developed. Methyl aryl ethers are successfully cleaved by the halide anion of [bmim][Br], without aid of any other activating agents. In this reaction, microwave irradiation was found to be crucial for the effective conversion. The newly developed protocol is a very attractive green chemical process as it utilizes minimal amount of cleaving reagents and does not require additional activating agents or solvents. Under the conditions described herein, a broad range of methyl aryl ethers were converted to the corresponding phenolic compounds in moderate to excellent yields in a short time. Georg Thieme Verlag Stuttgart New York.
- Park, Jiyeon,Chae, Junghyun
-
experimental part
p. 1651 - 1656
(2010/08/22)
-
- Synthesis of phenol, aromatic ether, and benzofuran derivatives by copper-catalyzed hydroxylation of aryl halides
-
A smooth operator: The copper-catalyzed synthesis of phenols from aryl halides was carried out under relatively mild reaction conditions. Alkyl aryl ethers and benzofurans could also be prepared smoothly by one-pot domino protocols based on hydroxylation of aryl iodides (see scheme).
- Zhao, Dongbing,Wu, Ningjie,Zhang, Shuai,Xi, Peihua,Su, Xiaoyu,Lan, Jingbo,You, Jingsong
-
supporting information; experimental part
p. 8729 - 8732
(2010/01/16)
-
- HEAT-LABILE PRODRUGS
-
Disclosed herein are heat-labile prodrugs, their preparation and uses.
- -
-
Page/Page column 21
(2008/12/08)
-
- Propofol formulation containing reduced oil and surfactants
-
Sterile, stable pharmaceutical formulations of emulsions of neat propofol or propofol dissolved in a solvent and containing no preservative are provided that comprise optimal amounts of surfactants such as lecithin and solvent such as soybean oil, with a suitable pH range to prevent significant growth of microorganisms for at least 24 hours after adventitious, extrinsic contamination. The lower amount of oil or absence (oil) in the formulation also allows chronic sedation over extended periods of time with a reduced chance of lipid overload in the blood.
- -
-
-
- Base-labile tert-butoxycarbonyl (Boc) group on phenols
-
Phenols are deprotected with weak bases from their tert-butoxycarbonyl (Boc) derivatives. Boc deprotection with bases can avoid side reactions during the deprotection with acids. We note the lability of the Boc to bases and are able to utilize it as a new cleavage condition for synthetic studies.
- Nakamura, Kozo,Nakajima, Takero,Kayahara, Hiroshi,Nomura, Eisaku,Taniguchi, Hisaji
-
p. 495 - 499
(2007/10/03)
-
- A novel protecting group for hindered phenols
-
Boc2O and DMAP were used to protect hindered phenols as their Boc derivatives under mild conditions. Deprotection conditions were developed to suppress loss of a tert-butyl group from the aromatic ring, or alkylation of an additional tert-butyl group at an unsubstituted ortho or para position.
- Hansen, Marvin M.,Riggs, Jennifer R.
-
p. 2705 - 2706
(2007/10/03)
-
- Propofol purification
-
Propofol is purified by reaction of the raw 2,6-diisopropylphenol with an alkaline agent, by isolation of the alkaline metal salt and by neutralization thereof. There is thus obtained a propofol having a purity of at least 99.90%.
- -
-
-
- β-carboxy sulfonamide ACAT inhibitors
-
β-Carboxy sulfonyl compounds of the formula STR1 wherein R1 is aryl, R3 is hydrogen or alkyl, R3 and R4 are hydrogen or alkyl, Y is --O--, --S--, or --NR2 --, and R5 is alkyl or aryl are potent inhibitors of the enzyme acyl CoA:cholesterol acyltransferase (ACAT) and are thus useful for treating hypercholesterolemia and atherosclerosis.
- -
-
-
- Process of purification of 2,6-diisopropylphenol
-
A process for the purification of 2,6-diisopropylphenol (Propofol) by transformation of the crude Propofol into its ester with a carboxylic or sulphonic acid, crystallization and hydrolysis, is described.
- -
-
-
- N-acyl sulfamic acid esters (or thioesters), N-acyl sulfonamides, and N-sulfonyl carbamic acid esters (or thioesters) as hypercholesterolemic agents
-
The present invention is directed to compounds useful for the regulation of cholesterol of Formula I, methods for using them and pharmaceutical compositions thereof, STR1 wherein X and Y are oxygen, sulfur, or (CR'R")n wherein n is 1 to 4; R is hydrogen, alkyl, or benzyl; R1 and R2 are phenyl, substituted phenyl, naphthyl, substituted naphthyl, an aralkyl group, an alkyl chain, adamantyl, or a cycloalkyl group.
- -
-
-
- Process for producing ortho-isopropylated phenol derivatives
-
This invention relates to the process for producing ortho-isopropylated phenol derivatives having following general formula (VIII). STR1 (in the above formula, R1 is a hydrogen or a low alkyl group of C1 -C4) A process for producing ortho-isopropylated phenol derivatives (VIII) of the present invention is characterized by obtaining position isomer desired by means of Claisen rearrangement of phenyl allyl ether without catalyst in atmosphere, and then obtaining only one isomer by oxidation and reduction of the above-obtained position isomer. According to the present invention, ortho-alkylated phenol derivatives (VIII) having high purity at low temperature and low pressure can be prepared without producing a by-product and requirement of the complicated separation procedure.
- -
-
-
- Cross-coupling reactions of d2 tantalum alkyne complexes: Selective 1,3-diene syntheses and their relevance to alkyne cyclization chemistry
-
Ta(DIPP)3Cl2(OEt2) (DIPP = 2,6-diisopropylphenoxide) can be reduced by two electrons in the presence of the bulky alkynes PhC≡CPh and Me3SiC≡CMe to provide the pale yellow adducts (DIPP)3Ta-(PhC≡CPh) (1) and (DIPP)3Ta(Me3SiC≡CMe) (2). The reduction of Ta(DIPP)3Cl2(OEt2) in the presence of smaller internal alkynes (viz. EtC≡CEt) or the terminal alkynes Me3SiC≡CH or Me3CC≡CH affords the metallacyclopentadienes (DIPP)3Ta(CEt=CEtCEt=CEt) (3) or (DIPP)3Ta(CR=CHCR=CH) (4, R = SiMe3; 5, R = CMe3) directly. The molecular structure of the PhC≡CPh adduct 1 is approximately tetrahedral (L-Ta-L angles average 109.4°) and features very short Ta-Calkyne distances (2.070 (3) and 2.076 (3) A?, respectively) and an elongated "C≡C" bond (1.346 (5) A?, which indicate a strongly bound and substantially reduced alkyne ligand. The molecular structure of metallacycle 3 reveals a trigonal bipyramidal geometry (Lax-Ta-Lax = 164.9 (3)°) with the metallacyclic α carbons occupying one axial and one equatorial site. The alkyne complex (DIPP)3Ta(PhC≡CPh) (1) reacts with MeC≡CMe, EtC≡CEt, Me3CC≡CH, Me3SiC≡CH, or PhC≡CH to afford high yields of the metallacyclization products (DIPP)3Ta(CPh=CPhCMe=CMe) (6), (DIPP)3Ta(CPh=CPhCEt=CEt) (7), (DIPP)3Ta-(CPh=CPhCH=CCMe3) (8), (DIPP)3Ta(CPh=CPhCH=CSiMe3) (9), and (DIPP)3Ta-(CPh=CPhCH=CPh) (10), respectively, while 1,7-octadiyne HC≡C(CH2)4C≡CH reacts with 2 equiv of (DIPP)3Ta(PhC≡CPh) to provide the unusual bimetallic complex (DIPP)3Ta(CPh=CPhCH=C(CH2) 4-C=CHCPh=PhC)Ta(DIPP)3 (11). The alkyne adduct (DIPP)3Ta(Me3SiC≡CMe) (2) also engages in metallacyclization chemistry as it reacts with MeC≡CMe to afford (DIPP)3Ta(CMe=CSiMe3CMe=CMe) (12), with PhC≡CH to provide (DIPP)3Ta(CSiMe3=CMeCPh=CH) (13), and with Me3CC≡CH to afford (DIPP)3Ta(CCMe3=CHCSiMe3=CMe) (14). All of the metallacyclopentadiene complexes can be hydrolyzed with H2O/acetone solutions to afford the corresponding 1,3-dienes in essentially quantitative yields. However, iodination of metallacycles 6, 7, and 13 does not yield the expected 1,4-diiodo-1,3-dienes, but rather the ring-opened monoiodinated butadienyl compounds (DIPP)3(I)TaCPh=CPhCMe=CMe(I) (15), (DIPP)3(I)TaCPh=CPhCEt=CEt(I) (16), and (DIPP)3(I)TaCSiMe3=CMeCPh=CH(I) (17), respectively. The subsequent hydrolysis of compounds 15-17 provides the corresponding 1-iodo-1,3-dienes.
- Strickler, Jamie R.,Wexler, Pamela A.,Wigley, David E.
-
p. 118 - 127
(2008/10/08)
-
- KINETICS OF ESTERIFICATION OF DIISOPROPYLPHENOLS WITH PHOSPHORYL TRICHLORIDE
-
The title liquid-phase isothermal esterification kinetics have been measured in the temperature intervals of 110-125 and 110-160 deg C for 2,4- and 2,6-diisopropylphenols, resp.The values measured have been used to calculate the rate constants of the respective three steps and to determine the activation energies. 2,6-Diisopropylphenol has been found to react only to the first degree, and the rate constants of the other two reaction steps (k2, k3) were only calculated from the differential equations given by means of a computer.
- Magura, Miroslav,Vojtko, Jan,Ilavsky, Jan
-
p. 2099 - 2104
(2007/10/02)
-
- Antioxidant synthesis
-
A process for making a 2,6-di-hydrocarbyl-4-alkoxyalkylphenol, e.g. 2,6-di-tert-butyl-4-methoxymethylphenol, by reacting a 2,6-dihydrocarbylphenol with formaldehyde in a stoichiometric excess of alcohol and in the presence of a Mannich base catalyst preferably formed in situ by adding a catalyst-forming amount of a secondary amine, e.g. dimethylamine, to the mixture of 2,6-di-hydrocarbylphenol, formaldehyde and alcohol. Unreacted alcohol and amine are distilled out and the 2,6-di-hydrocarbyl-4-alkoxyalkylphenol is reacted with a benzene-type compound, e.g. mesitylene, to make a hindered phenolic antioxidant, e.g. 1,3,5-trimethyl-2,4,6-tri-(3,5-di-tert-butyl-4-hydroxybenzyl)benzene.
- -
-
-
- Preparation of diphenolics
-
A process for the production of diphenolic compounds having a divalent bridge. A first disubstituted phenol is reacted with an aldehyde in the presence of a secondary amine and excess alcohol to form an ether intermediate. The ether intermediate is reacted with a phenol having an open ortho or para position to form a diphenolic.
- -
-
-
- Preparation of substituted phenols
-
Substituted phenols of the general formula I STR1 where R1, R2, R3, R4 and R5 are each hydrogen or an aliphatic or aromatic hydrocarbon radical, are prepared by dehydrogenating a cyclic alcohol of the general formula II STR2 or a cyclic ketone of the general formula III STR3 where one of the broken lines can be an additional C-C bond, in the gas phase at from 150° to 380° C. over a supported noble metal catalyst, by a process in which the dehydrogenation catalyst used is palladium or platinum on an aluminum spinel carrier, in particular an aluminum spinel which has a BET specific surface area of from 5 to 150 m2 /g or, for the dehydrogenation of cyclohexenones, preferably from 10 to 50 m2 /g. Particularly suitable aluminum spinels are those which, in addition to aluminum, contain magnesium, zinc, cobalt or nickel. In the novel process, substituted phenols are obtained in high yields and selectivities, and the catalyst has an extremely long life without a significant decrease in activity.
- -
-
-
- Alumina-Catalyzed Reactions of Hydroxyarenes and Hydroaromatic Ketones. 10. Reaction of Phenol with 2-Propanol
-
At 300-350 deg C in the presence of alumina, phenol (1) reacts with excess 2-propanol (37) to give mixed monopropyl-, dipropyl-, and 2,4,6-triisopropyl- (42) phenols. At 300 deg C the principal components of the product mixture are 2-isopropylphenol (26-30 mol percent yield) and 2,6-diisopropylphenol (44-52percent); at 350-400 deg C , they are the isomeric monoisopropylphenols (50-60percent). With 3-isopropylphenol as substrate (instead of 1), 2,5-diisopropylphenol is obtained (79percent), while 4-isopropylphenol gives 2,4-diisopropylphenol and 42 (70percent combined yield). In various runs, 0-20percent of the propyl groups introduced are n-propyl ones. It is proposed that the principal products result from an SN2-type reaction mechanism which involves nucleophilic attack (variously by C-2, C-4, and C-6) of an adsorbed ambident phenoxide ion onto C-2 of an adsorbed isopropoxide group. n-Propylation is ascribed to a side reaction of SN1 type.
- Klemm, LeRoy H.,Taylor, Dennis R.
-
p. 4326 - 4329
(2007/10/02)
-
