- Hydroxyalkylation of p-cresol to 2,2′-methylenebis(4-methylphenol) using Sn/Si-MCM-41 catalysts
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Sn/Si-MCM-41 has exhibited an excellent catalytic activity [70% product yield with 88% selectivity to 2,2′-methylenebis(4methylphenol)] for the selective hydroxyalkylation of p-cresol. At equal level of Sn loading, Sn/Si-MCM-41 prepared by direct hydrothermal synthesis showed higher activity than Sn-impregnated Si-MCM-41 catalyst.
- Garade, Ajit C.,Niphadkar, Prashant S.,Joshi, Praphulla N.,Rode, Chandrashekhar V.
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Read Online
- Catalytic Activation of Unstrained C(Aryl)-C(Alkyl) Bonds in 2,2′-Methylenediphenols
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Catalytic activation of unstrained and nonpolar C-C bonds remains a largely unmet challenge. Here, we describe our detailed efforts in developing a rhodium-catalyzed hydrogenolysis of unstrained C(aryl)-C(alkyl) bonds in 2,2′-methylenediphenols aided by removable directing groups. Good yields of the monophenol products are obtained with tolerating a wide range of functional groups. In addition, the reaction is scalable, and the catalyst loading can be reduced to as low as 0.5 mol %. Moreover, this method proves to be effective to cleave C(aryl)-C(alkyl) linkages in both models of phenolic resins and commercial novolacs resins. Finally, detailed experimental and computational mechanistic studies show that with C-H activation being a competitive but reversible off-cycle reaction, this transformation goes through a directed C(aryl)-C(alkyl) oxidative addition pathway.
- Dong, Guangbin,Ratchford, Benjamin L.,Xue, Yibin,Zhang, Rui,Zhu, Jun
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supporting information
p. 3242 - 3249
(2022/02/23)
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- One-step novel synthesis of methylene bisphenols and methylene bisnaphthols using Lewis acid mediated rearrangement
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Mono- and di-substituted isomeric methylene bisphenols and methylene bisnaphthols have been synthesized by rearrangement of the corresponding O-methoxyacetyl derivatives of phenols and naphthols, respectively, in presence of aluminium chloride under dry conditions. The chemistry observed is different from the usual Fries rearrangement reaction and involves an intermolecular rearrangement. The reactions reported here also reflect the influence of substituents present in the substrate as is supported by the substitution of the bridging methylene at a position meta to the phenolic hydroxyl in some of the minor products formed along-side the majorly formed ortho substituted products.
- Kumar, Sandeep,Mehta, Shilpika Bali
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- Lignin-based diphenylmethane diisocyanate as well as preparation method and application thereof
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The invention discloses a lignin-based diphenylmethane diisocyanate and a preparation method and application thereof. As shown in Formula I, the lignin-based diphenylmethane diisocyanate is prepared by reacting a lignin-cracking monomer compound II with a carbonyl compound to give compound III, compound III reacts with chloroacetyl ammonia to obtain compound IV, compound IV is subjected Smiles rearrangement reaction to obtain compound V, and compound V is reacted with a compound containing carbon-containing acid to obtain the lignin-based diphenylmethane diisocyanate shown in formula I. The product replaces MDI for synthesis of polyurethane materials, and the toughness of the polyurethane material is improved. Thermal stability and glass transition temperature. When being applied to polyurethane waterproof coating, the water absorption rate is obviously reduced, and the stability of the coating is improved.
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Paragraph 0093-0096
(2021/11/21)
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- Synthesis of Monofunctionalized Calix[5]arenes
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Seven OH-free and O -permethylated monofunctionalized calix[5]arenes carrying either additional methyl or tert -butyl groups are prepared following fragment condensation protocols. This strategy proves to be superior to previous approaches. Calix[5]arenes with free OH groups all adopt a cone conformation stabilized by a seam of hydrogen bonds at the lower rim. Post-condensation modifications, i.e., methylation of phenolic OH groups or functional group interconversions can also be achieved. Bulky tert -butyl groups are also found to stabilize the cone conformations of O -methylated compounds. These compounds offer versatile functional groups that make these concave molecules interesting building blocks for the synthesis of more sophisticated molecular architectures.
- Ingenfeld, Bj?rn,Straub, Steffen,Fr?mbgen, Christopher,Lützen, Arne
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p. 676 - 684
(2017/11/16)
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- Effect of SnO2/Al2O3 ratio of Si-based MFI on its acidity and hydrophobicity: Application in selective hydroxyalkylation of p-cresol
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Silica based MFI type molecular sieves with various SnO2/Al 2O3 ratios were synthesized from gels having molar compositions SiO2:xSnO2:yAl2O 3:0.23(TPA)2O:35H2O where 0 ≤ x ≤ 0.02 and 0 ≤ y ≤ 0.01. Recyclable, Al-free Sn-MFI catalyst showed 31% conversion of formaldehyde with 100% selectivity to 2,2′-methylenebis(4- methylphenol) in hydroxyalkylation of p-cresol with formaldehyde on account of moderate acidity and higher hydrophobicity.
- Garade,Malwadkar,Niphadkar,Jha,Joshi,Rode
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- Structure-activity studies of dodecatungstophosphoric acid impregnated bentonite clay catalyst in hydroxyalkylation of p-cresol
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Bentonite clay impregnated with dodecatungstophosphoric acid (20% DTP/BNT) showed an excellent activity, selectivity and stability [95% product yield with 94% selectivity to 2, 2′-methylenebis (4-methylphenol), DAM] for the hydroxyalkylation of p-cresol with formaldehyde at 353 K and for a mole ratio of 5. Ammonia-TPD results showed that an increase in total concentration of acid sites from 4.9 of parent bentonite to 11.6 micromoles per surface area NH3 (μmolS-1 NH3) of 20% DTP/BNT was due to a strong interaction of protons of bulk DTP with surface hydroxyl groups of BNT as evidenced by 31P NMR studies.
- Garade,Kshirsagar,Jha,Rode
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experimental part
p. 942 - 945
(2010/11/18)
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- Cyclophosphites from oligomethylenephenols
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New types of oligomethylenephenol cyclophosphites containing 1-3 phosphorus atoms are synthesized by reactions of available oligomethylenephenols with phosphorous acid amides. Contrary to their simple analogs, the resulting phosphites are stable on handling, which allowed design on their basis of complex coordination systems holding promise for metal complex catalysis.
- Nifant'ev,Teleshev,Zhdanov
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p. 903 - 908
(2007/10/03)
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- Metal-template ortho-regioselective mono- and bis-de-tert-butylation of poly-tert-butylated phenols
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A metal-template ortho-regioselective mono- and bis-de-tert-butylation of poly-tert-butylated phenol-formaldehyde oligomers is reported.
- Sartori, Giovanni,Bigi, Franca,Maggi, Raimondo,Porta, Cecilia
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p. 7073 - 7076
(2007/10/02)
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- Magnesium-mediated ortho-Specific Formylation and Formaldoximation of Phenols
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Deprotonation of phenols using magnesium methoxide, followed by distillative removal of free methanol and addition of paraformaldehyde results in ortho-specific magnesium mediated formylation to give the corresponding salicyladehyde magnesium salts, from which the salicylaldehydes can be isolated by acidic work-up.Addition of aq. hydroxylamine sulfate to the salicylaldehyde magnesium salt, in place of the acid work-up, gives the corresponding salicylaldoximes.
- Aldred, Robert,Johnston, Robert,Levin, Daniel,Neilan, James
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p. 1823 - 1832
(2007/10/02)
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- Carbonates of acetylenic alcohols
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Polymerizable carbonate compounds of the formula: wherein A is an aromatic polycycle, R1 and R2 are independently hydrogen atom or alkyl, and n is 1, 2 or 3, are disclosed. They are useful as a component of nonemanating, self-curing and heat resistant resin compositions.
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