53751-40-9Relevant academic research and scientific papers
Investigating homogeneous Co/Br-/H2O2 catalysed oxidation of lignin model compounds in acetic acid
Clatworthy, Edwin B.,Picone-Murray, Julia L.,Yuen, Alexander K. L.,Maschmeyer, Richard T.,Masters, Anthony F.,Maschmeyer, Thomas
, p. 384 - 397 (2019/01/28)
Oxidation of α-O-4, β-O-4 and monomeric lignin model compounds by Co/Br-/H2O2 in acetic acid at 70 °C was investigated. Co and Br- were introduced as cobalt acetate tetrahydrate and KBr respectively. The degree of methoxylation of the substrate was found to affect its reactivity. For the α-O-4 model compounds, increased methoxylation of the benzyl moiety influenced product selectivity, while increased methoxylation of the phenolic moiety increased substrate conversion. The β-O-4 model compounds exhibited similar conversions to the α-O-4 models, but afforded a lesser amount of monomeric products. The formation of phenol and guaiacol from α-O-4 bond cleavage inhibited substrate conversion and sequestered oxidation products due to the formation of phenoxy radicals and polyguaiacols. Similar to the α-O-4 model compounds, increased methoxylation of the monomers changed the types of products formed, from polyphenols (phenol and guaiacol) to quinones (syringol). The behaviour of syringol was explored extensively, revealing that the corresponding 1,4-hydroquinone strongly inhibited syringol oxidation, and the syringol oxidation product, 4,4′-diphenoquinone, was susceptible to over-oxidation. The deleterious effects of phenols on oxidation of an α-O-4 model could be reduced by substitution of the Br- co-catalyst with N-hydroxyphthalimide (NHPI), improving substrate conversion and product selectivity.
Selective acetylation of primary alcohols by ethyl acetate
Singha, Raju,Ray, Jayanta K.
supporting information, p. 5395 - 5398 (2016/11/11)
A KOtBu and ethyl acetate mediated efficient methodology has been developed for the acetylation of primary and secondary alcohols where ethyl acetate is the source of acetyl group. The reaction is fast, mild, efficient, and highly selective towards the primary alcohols.
Electrogenerated N-heterocyclic carbenes in the room temperature parent ionic liquid as an efficient medium for transesterification/acylation reactions
Chiarotto, Isabella,Feroci, Marta,Sotgiu, Giovanni,Inesi, Achille
supporting information, p. 326 - 331 (2013/02/25)
N-Heterocyclic carbenes (NHCs), generated by electrochemical reduction under galvanostatic control of 1,3-dialkylimidazolium-based ionic liquids, were employed as catalysts in transesterification reactions in the parent, room temperature ionic liquids (RTILs) as solvents, without the utilisation of any volatile organic solvent or base. The reaction between isopropenyl or ethyl acetate and an alcohol (not efficient in the absence of catalyst) was induced by the presence of an electrogenerated NHC, which seems to assist the proton transfer from the alcohol to the ester, yielding the corresponding acetate. The reaction also proceeds with methyl nicotinate as starting ester and 2-(diethylamino)ethanol or benzyl alcohol as alcohols and leads to the corresponding biologically active compounds, nicametate and benzyl nicotinate, in good yields. All products were isolated in good to excellent yields and complete recyclability of the ionic liquid as solvent has been demonstrated.
Trialkylsilyl triflimides as easily tunable organocatalysts for allylation and benzylation of silyl carbon nucleophiles with non-genotoxic reagents
Mendoza, Oscar,Rossey, Guy,Ghosez, Léon
supporting information; experimental part, p. 2571 - 2575 (2010/06/21)
Trialkylsilyl triflimides generated in situ are unique catalysts for the electrophilic benzylation or allylation of trialkylsilylenol ethers or allyl trialkylsilanes with non-genotoxic alkylating reagents such as benzyl and allyl acetates. In most cases the reactions are fast at room temperature and yields are high. The reaction works particularly well with electron-rich benzyl donors including derivatives of pyrrole, indole and furane.
One-pot sequence for reductive-acetylation of carbonyl compounds with (N-methylimidazole)(tetrahydroborato)zinc complex
Setamdideh, Davood,Khezri, Behrooz
experimental part, p. 5766 - 5772 (2012/07/28)
Reductive-acetylation of variety of aliphatic and aromatic aldehydes and ketones, α,β-unsaturated carbonyl compounds are examined efficiently with (N-methylimidazole)(tetrahydroborato)zinc complex, [Zn(BH4) 2(nmi)], under mild condition in THF at room temperature or reflux conditions. The corresponding acetates were obtained in excellent yields (90-98 %).
Simple and efficient method for acetylation of alcohols, phenols, amines, and thiols using anhydrous NiCl2 under solvent-free conditions
Meshram, Gangadhar,Patil, Vishvanath D.
experimental part, p. 4384 - 4395 (2010/04/29)
Solvent-free acetylation of alcohols, phenols, amines, and thiols with acetic anhydride (Ac2O) in the presence of 0.1mol% (13mg) anhydrous NiCl2, an inexpensive and easily available catalyst, is described. Excellent yields, short reaction time, and mild reaction conditions are important features of this method.
Separation, recovery and reuse of N-heterocyclic carbene catalysts in transesterification reactions
Zeng, Tieqiang,Song, Gonghua,Li, Chao-Jun
supporting information; experimental part, p. 6249 - 6251 (2010/02/16)
A novel and convenient strategy to separate, recover and reuse N-heterocyclic carbene catalysts in transesterification reactions has been developed.
The unusual characteristics of the aerobic oxidation of 3,4-dimethoxytoluene with metal/bromide catalysts
Partenheimer, Walt
, p. 1495 - 1500 (2007/10/03)
DMtoluene (3,4-dimethoxytoluene; DM = 3,4-dimethoxy), a model compound for lignin oxidation, can be autoxidized in acetic acid using a Co/Mn/Br catalyst to its benzaldehyde in 51 mol % yield, and to its acid in 85-92 mol % yield. This synthesis is unusual because a number of unprecedented phenomena occur. 1) The rate of molecular oxygen reacting with the substrate is bi-phasic, i.e., two maximum in the rate of reaction are observed. 2) In the first phase, all of the 3,4-dimethoxytoluene is converted to intermediates, but very little to the carboxylic acid. 3) During the second maximum of activity, virtually all the intermediates are converted to the carboxylic acid with 95-100% mass accountability. 4) The rate of carbon monoxide and carbon dioxide formation is considerably higher during the second phase during which 5) 9-12% of methyl 3,4-dimethoxybenzoate (the methyl ester of the benzoic acid) is formed. Mechanisms are suggested for these unusual phenomena.
Electrostatic catalysis by ionic aggregates: Scope and limitations of Mg(ClO4)2 as acylation catalyst
Chakraborti, Asit K.,Sharma, Lalima,Gulhane, Rajesh,Shivani
, p. 7661 - 7668 (2007/10/03)
Alkali and alkaline earth metal perchlorates exhibit electrostatic catalysis in the activation of anhydrides for the acylation reaction. Perchlorates with higher values of the charge-size function of the metal ion exhibit better catalytic activity following the order Mg(ClO4) 2>Ba(ClO4)2>LiClO4. Acylation of structurally diverse phenols, thiols, alcohols, and amines have been carried out with stoichiometric amounts of anhydride at room temperature under solvent free conditions in the presence of catalytic amount of Mg(ClO4) 2. Sterically hindered and electron deficient phenols are efficiently acylated. Acylation with sterically hindered anhydrides such as iso-butyric, pivalic, and benzoic anhydrides are carried out with phenols and alcohols in excellent yields. Acid-sensitive alcohols are acylated in excellent yields without any competitive side reactions.
Liquid phase acylation of alcohols with acetic acid over zeolites
Narender,Srinivasu,Kulkarni,Raghavan
, p. 1887 - 1893 (2007/10/03)
The liquid phase acylation of primary and secondary alcohols were carried out with acetic acid in the presence of zeolites. LaY zeolite is found to be the best catalyst.
