16474-43-4Relevant articles and documents
Design and synthesis of sulfonated carbons with amphiphilic properties
Jia, Rong,Ren, Jiawen,Liu, Xiaohui,Lu, Guanzhong,Wang, Yanqin
, p. 11195 - 11201 (2014/07/21)
A new type of sulfonated carbon material with amphiphilic properties was synthesized by the hydrothermal carbonization of a mixture of furfural-sodium dodecylbenzene sulfonate at 180 °C in an autoclave. The addition of SDBS is necessary for the production of materials with long carbon chains and is possibly used to improve the solubilization of long carbon-chain and steric compounds such as pivalic acid. The resulting material was characterized by N2 adsorption, XPS, 13C NMR, XRD and FTIR. The synthesized material was proven to be a highly efficient solid-acid catalyst in reactions such as the esterification of pivalic acid with alcohols, and catalytic performance much better than that of conventional solid acid catalysts, e.g. Amberlyst-15 and Nafion resin, was observed.
Nucleophilic acyl substitutions of anhydrides with protic nucleophiles catalyzed by amphoteric, oxomolybdenum species
Chen, Chien-Tien,Kuo, Jen-Huang,Pawar, Vijay D.,Munot, Yogesh S.,Weng, Shieu-Shien,Ku, Cheng-Hsiu,Liu, Cheng-Yuan
, p. 1188 - 1197 (2007/10/03)
(Chemical Equation Presented) Among six different group VIb oxometallic species examined, dioxomolybdenum dichloride and oxomolybdenum tetrachloride were the most efficient catalysts to facilitate nucleophilic acyl substitution (NAS) of anhydrides with a myriad array of alcohols, amines, and thiols in high yields and high chemoselectivity. In contrast to the well-recognized redox chemical behaviors associated with oxomolybdenum(VI) species, the catalytic NAS was unprecedented and tolerates virtually all kinds of functional groups. By using benzoic anhydride as a mediator for in situ generation of an incipient mixed anhydride-MoO2Cl2 adduct with a given functional alkanoic acid, one can achieve oleate, dipeptide, diphenylmethyl, N-Fmoc-α-amino, pyruvic, and tert-butylthio ester, N-tert-butylamide, and trityl methacrylate syntheses with appropriate protic nucleophiles. The amphoteric character of the Mo=O unit in oxomolybdenum chlorides was found to be responsible for the catalytic NAS profile as supported by a control NAS reaction of using an authentic adduct-MoOCl2(O2-CBu t)2 between pivalic anhydride and MoO2Cl 2 as the catalyst.
Hindered ester formation by SN2 azidation of N-acetoxy-N-alkoxyamides and N-alkoxy-N-chloroamides-novel application of HERON rearrangements
Glover, Stephen A.,Mo, Guoning
, p. 1728 - 1739 (2007/10/03)
Treatment of N-acetoxy-N-alkoxyamides or N-alkoxy-N-chloroamides with sodium azide in aqueous acetonitrile results in SN2 displacement of chloride and the formation of reactive N-alkoxy-N-azidoamides. The reaction with N-acetoxy-N-benzyloxybenzamide has been studied kinetically (k294 = 2 L mol-1 s-1) and azidation of N-formyloxy-N-methoxyformamide has been modeled computationally at the pBP/DN*//HF/6-31G* level of theory. The anomeric amides N-alkoxy-N-azidoamides decompose intermolecularly and spontaneously to esters and two equivalents of nitrogen. This extremely exothermic process facilitates the formation, in excellent yields, of highly hindered esters.
1-(2,5-dichlorophenyl)-2,2-bis(methylsulfanyl)vinyl esters as highly efficient chemoselective acylating reagents
Degani,Dughera,Fochi,Serra
, p. 1200 - 1208 (2007/10/03)
1-(2,5-Dichlorophenyl)-2,2-bis(methylsulfanyl)vinyl esters 4f-k were prepared in yields usually greater than 90%, by reacting acyl chlorides with 1-(2,5-dichlorophenyl)-2,2-bis(methylsulfanyl)ethanone enolate. These esters were demonstrated to be excellent chemoselective reagents for the acylation of amines, alcohols, thiols, pyrrole and indole. From all the acylation reactions the dimethyl α-oxo dithioacetal 2d, recyclable for the preparation of esters 4f-k, could be recovered in 90-100% yield.
'New' catalysts for the ester-interchange reaction: The role of alkali-metal alkoxide clusters in achieving unprecedented reaction rates
Stanton, Matthew G.
, p. 5981 - 5989 (2007/10/03)
The catalytic effect of alkali-metal tert-butoxide clusters on the rate of ester interchange for several pairs of esters has been determined in nonpolar and weakly polar solvents. Reactivities increase in the order (Li+ + + + +) with the fastest rates reaching 107 catalytic turnovers per hour (TO/h). Ester interchange rates were sensitive to the size of both the transferring OR groups and the ester substituent. Phenyl esters did not exchange with aliphatic esters due to nonstatistical breakdown patterns in the tetrahedral intermediate. A first-order equilibration analysis on the interchange between tert-butyl acetate (tBuAc) and methyl benzoate (MeBz) (5 mol % NaOtBu) indicated enhanced reaction rates as the reaction proceeded. Isolation and quenching (DCl/D2O) of precipitated catalyst points to a mechanism whereby sequential methoxy incorporation into the catalyst cluster increases activity, but eventually precipitates out of solution as a 3:1 OMe:OtBu cluster. The rate law was determined to be k(obs)[MeBz]1[tBuAc]0[NaOtBu](x), where x = 1.2(1), 1.4(1), and 0.85(1) in hexane, ether, and THF, respectively, under conditions where tetrameric catalyst aggregates are expected. Reaction rates were generally observed to be higher in nonpolar solvents (hexane > toluene, ether > THF). Eyring analysis over a 40°C range yielded ΔH(≠) = 10.0(1) kcal mol-1 and ΔS(≠) = -32(3) eu. A Hammett (σ) plot generated with para-substituted methyl benzoates gave ρ +2.35 (R 0.996). These results are interpreted in terms of a catalytic cycle composed of two coupled transesterification reactions with a turnover-limiting addition of a tert-butoxy-containing cluster (tetramer) to methyl benzoate. Catalyst relative reactivities (Cs+ > Rb+ > K+ > Na+ > Li+) are interpreted in terms of competitive electrostatic interactions between the alkali-metal and ground-state and transition-state anions. This analysis predicts the observed linear dependence between log(k(obs)) and l/r(ionic).
Nitrolysis of carboxylic t-butyl and 1-adamantyl esters
Strazzolini, Paolo,Dali'Arche, Maria Grazia,Giumanini, Angelo G.
, p. 9255 - 9258 (2007/10/03)
A cheap, less problematic, efficient and selective reagent for the removal of the t-butyl and 1-adamantyl protecting groups from carboxylic esters was found to be commercial 100% HNO3 in CH2Cl2. Incidentally, 1,1- dimethylethyl nitrate and tricyclo[3.3.1.13,7]dec-1-yl (1-adamantyl) nitrate are coproducts in a clean reaction. The procedure is in many ways superior to the method employing CF3COOH.
Zinc promoted mild and efficient method for the esterification of acid chlorides with alcohols
Yadav,Reddy, Gondi Sudershan,Srinivas, Dale,Himabindu, Konuru
, p. 2337 - 2342 (2007/10/03)
The esterification of variety of acid chlorides with alcohols in the presence of zinc is described. The easy formation of t-butyl and pivaloyl esters are the additional importance of this procedure.
A novel, general route to the synthesis of carboxylic acid esters and thiolesters
Sucheta,Reddy,Ravi,Rama Rao
, p. 4415 - 4416 (2007/10/02)
Carboxylic acids were conveniently esterified with alcohols and thiols by the use of triphenylphosphine and N-bromo/Iodo succinimide to afford the corresponding esters and thiol esters.
A Mild and Efficient Alumina-Promoted Synthesis of t-Butyl Esters
Nagasawa, Kazuo,Yoshitake, Shinji,Amiya, Takao,Ito, Keiichi
, p. 2033 - 2040 (2007/10/02)
A wide variety of aliphatic acid chlorides including an optically active one has been efficiently converted to their t-butyl esters under very mild reaction conditions by employing activated alumina as a catalyst.
DECARBOXYLATION OF ALKOXYCARBONYLCOBALT CARBONYLS
Bartik, Tamas,Kruemmling, Thomas,Marko, Laszlo,Palyi, Gyula
, p. 307 - 308 (2007/10/02)
Alkoxycarbonylcobalt tetracarbonyls undergo thermal decarboxylation between 25 and 90 deg C yielding up to 67percent CO2/Co atom; the decarboxylation is favoured by ligand excess (CO, PR3, NEt3).