- Proton chemical shift assignments in citrate and trimethyl citrate in chiral media
-
The citrate ion gives rise to four different methylene proton chemical shifts in the presence of (S)-lactate and Pr3+ Trimethyl citrate behaves similarly in the presence of (S)-2,2,2-trifluoro-l-(9-anthryl)ethanol. The four methylene shifts have been assigned in an absolute way by comparisons with those from the corresponding spectra of (2R,3R)-citrate-2-d and trimethyl (2R,3R)-citrate-2-d, respectively. The chemical shifts of the three methyl groups in trimethyl citrate in the presence of the anthryl shift reagent have also been assigned. Deuterium isotope effects on the proton chemical shifts of these molecules have been determined. In the absence of shift reagents these effects are mainly of the intrinsic type, but in their presence there are equilibrium perturbation contributions. The 1H NMR line widths and chemical shifts in the citrate-lactate-PrCl3 system depend strongly on the pH, spectrometer frequency, and temperature, with the best results obtained at room temperature pH ≈3.8, and a spectrometer frequency of 200 MHz.
- Anet, Frank A.L.,Park, Jaemin
-
-
Read Online
- A FACILE PREPARATION OF ASYM-MONOMETHYL, SYM-MONOMETHYL AND ASYM-DIMETHYL CITRATE
-
Asym-monomethyl citrate was prepared by hydrolysis of sym-dimethyl citrate.Sym-monomethyl and sym-dimethyl citrate were prepared by a selective hydrolysis of trimethyl citrate.
- Hirota, Kazuhiro,Kitagawa, Harukazu,Shimamura, Michiya,Ohmori, Shinji
-
-
Read Online
- Citrate plasticizer
-
The invention discloses a citrate plasticizer and a preparation method thereof, and the preparation method of citrate comprises the following steps: firstly, citric acid and alcohol react to prepare citric acid triester, and then dianhydride acylation is carried out to prepare carboxyl-containing citric acid triester. After chlorination, the carboxyl-containing citric acid triester and the tris(2-ethoxyl) isocyanurate are subjected to esterification reaction to prepare triester citrate containing the isocyanurate. According to the present invention, the preparation method has characteristics of simple operation, wide raw material source and mild reaction condition, and meets the industrial production, the prepared triester citrate containing isocyanurate has a good plasticizing effect and excellent thermal stability, low-temperature flexibility, solvent extraction resistance, migration resistance and flame retardance, and can be widely applied to plastic rubber plasticizers.
- -
-
Paragraph 0061-0063
(2021/05/15)
-
- A Br?nsted acidic, ionic liquid containing, heteropolyacid functionalized polysiloxane network as a highly selective catalyst for the esterification of dicarboxylic acids
-
A Br?nsted acidic, ionic liquid containing, heteropolyanion functionalized polysiloxane network was formed by self-condensation of dodecatungstophosphoric acid and a zwitterionic organosilane precursor containing both imidazolinium and sulfonate groups. The resulting hybrid material POS-HPA-IL was investigated as a catalyst for the selective esterification of dicarboxylic acids.
- Rajabi, Fatemeh,Wilhelm, Christian,Thiel, Werner R.
-
supporting information
p. 4438 - 4444
(2020/08/10)
-
- 1,3-Dibromo-5,5-dimethylhydantoin as a Precatalyst for Activation of Carbonyl Functionality
-
Activation of carbonyl moiety is one of the most rudimentary approaches in organic synthesis and is crucial for a plethora of industrial-scale condensation reactions. In esterification and aldol condensation, which represent two of the most important reactions, the susceptibility of the carbonyl group to nucleophile attack allows the construction of a variety of useful organic compounds. In this context, there is a constant need for development of and improvement in the methods for addition-elimination reactions via activation of carbonyl functionality. In this paper, an advanced methodology for the direct esterification of carboxylic acids and alcohols, and for aldol condensation of aldehydes using widely available, inexpensive, and metal-free 1,3-dibromo-5,5-dimethylhydantoin under neat reaction conditions is reported. The method is air- and moisture-tolerant, allowing simple synthetic and isolation procedures for both reactions presented in this paper. The reaction pathway for esterification is proposed and a scale-up of certain industrially important derivatives is performed.
- ?ebular, Klara,Bo?i?, Bojan ?.,Stavber, Stojan
-
supporting information
(2019/08/01)
-
- METHOD FOR THE PRODUCTION OF METHYLSUCCINIC ACID AND THE ANHYDRIDE THEREOF FROM CITRIC ACID
-
A process for the preparation of methylsuccinic acid in any form, including its salts, its mono- and diester derivatives and the anhydride thereof, which comprises reacting citric acid or a derivative thereof in decarboxylation conditions, said process comprising (i) reacting citric acid or mono- and diester derivatives thereof in a non- aqueous solvent, specifically excluding alcohols, on a metallic catalyst at a temperature between 50 to 400°C and under a partial hydrogen pressure from 0.1 to 50 bar or (ii) reacting citric acid or any salt thereof or mono-, di- and triester derivatives thereof on a metallic catalyst in solvents comprising at least 5% water, at a temperature of from 50 to 400°C under a hydrogen partial pressure from 0.1 to 400 bar
- -
-
Page/Page column 16
(2018/04/21)
-
- Esterification of aryl/alkyl acids catalysed by n-bromosuccinimide under mild reaction conditions
-
N-halosuccinimides (NXSs) are well-known to be convenient, easily manipulable and low-priced halogenation reagents in organic synthesis. In the present work, N-bromosuccinimide (NBS) has been promoted as the most efficient and selective catalyst among the NXSs in the reaction of direct esterification of aryl and alkyl carboxylic acids. Comprehensive esterification of substituted benzoic acids, mono-, di- and tri-carboxy alkyl derivatives has been performed under neat reaction conditions. The method is metal-free, air- and moisture-tolerant, allowing for a simple synthetic and isolation procedure as well as the large-scale synthesis of aromatic and alkyl esters with yields up to 100%. Protocol for the recycling of the catalyst has been proposed.
- ?ebular, Klara,Bo?i?, Bojan ?.,Stavber, Stojan
-
-
- BIOFUELS PRODUCTION FROM BIO-DERIVED CARBOXYLIC-ACID ESTERS
-
A process for producing biofuels compounds directly from carboxylic acid esters recovered from a fermentation system is described. The process involves taking a fermentation broth that has been reduced to a dry powder containing free organic acids; reacting the carboxylic acid in the powder with an alcohol solvent under a CO2-containing atmosphere in substantial absence of any other acid catalyst at a reaction temperature and pressure that corresponds to supercritical, critical or near critical conditions for at least one of the alcohol or CO2 to synthesize an ester, then subjecting the ester to either hydrogenolysis or hydrogenation to form a biofuel.
- -
-
Paragraph 0058
(2017/04/11)
-
- Sulfonated graphene as highly efficient and reusable acid carbocatalyst for the synthesis of ester plasticizers
-
Plasticizers are well known for their effectiveness in producing flexible plastics. The automotive, plastic and pharmaceutical industries, essential to a healthy economy, rely heavily on plasticizers to produce everything from construction materials to medical devices, cosmetics, children toys, food wraps, adhesives, paints, and 'wonder drugs'. Although H2SO4 is commonly used as commodity catalyst for plasticizer synthesis it is energy-inefficient, non-recyclable, and requires tedious separation from the homogeneous reaction mixture resulting in abundant non-recyclable acid waste. In this study, for the first time, we report an efficient synthesis of ester plasticizers (>90% yields) using sulfonated graphene (GSO3H) as an energy-efficient, water tolerant, reusable and highly active solid acid carbocatalyst. The hydrothermal sulfonation of reduced graphene oxide with fuming H2SO4 at 120°C for 3 days afforded GSO3H with remarkable acid activity as demonstrated by 31P magic-angle spinning (MAS) NMR spectroscopy. The superior catalytic performance of GSO3H over traditional homogeneous acids, Amberlyst-15, and acidic ionic liquids has been attributed to the presence of highly acidic and stable sulfonic acid groups within the two dimensional graphene domain, which synergistically work for high mass transfer in the reaction. Furthermore, the preliminary experimental results indicate that GSO3H is quite effective as a catalyst in the esterification of oleic and salicylic acid and thus may pave the way for its broad industrial applications in the near future.
- Garg, Bhaskar,Bisht, Tanuja,Ling, Yong-Chien
-
p. 57297 - 57307
(2015/02/02)
-
- ALCOHOL-MEDIATED ESTERIFICATION OF CARBOXYLIC ACIDS WITH CARBONATES
-
A process for making esters from organic acids by means of reacting a carboxylic acid with dialkylcarbonate in an alcohol-containing solvent without any extrinsic acid or base catalyst is described. A benefit of the preparation process is that it can make the separation and extraction of ester products simpler and more facile vis-a-vis conventional isolation techniques.
- -
-
Page/Page column 10
(2014/05/24)
-
- HYDROGENATION PRODUCTS FROM BIOLOGICALLY-DERIVED CARBOXYLIC-ACID ESTERS
-
The production of organic acids in low-cost, high-efficiency fermentation system makes available a new route to chemical production from biomass. A process for producing a hydrogenation product involving carboxylic acid esters recovered directly from a fermentation process is described.
- -
-
Page/Page column 19
(2014/07/08)
-
- RASAGILINE CITRAMIDE
-
The subject invention provides rasagiline citramide and a composition containing N-propargyl-1(R)-aminoindan or a pharmaceutically acceptable salt thereof, and a compound of rasagiline citramide or a salt thereof.
- -
-
Paragraph 0133-0135
(2013/04/13)
-
- HYDRATE INHIBITORS
-
The present invention relates to compounds for controlling gas hydrate formation of the formula (I) and (II) and plugging of gas hydrate forming fluids wherein R1 is selected from the group consisting of H, acetyl and carbonyl derivative; R2 is H, -OR3 or -NR4R5, where: R3 is H, C1-6-alkyl or carbonyl derivative, R4, R5 are selected from the group consisting of H, C1-18-alkyl, alkanol, alkoxy, cyclic/aromatic or alkylene. The invention further comprises compositions and method of producing the compounds of formula (I) and (II), method for controlling gas hydrate formation and plugging of gas hydrate forming fluids, and use of compounds of formula (I) and (II).
- -
-
Page/Page column 36-38
(2010/09/18)
-
- Synthesis of citrate-ciprofloxacin conjugates
-
Two regioisomeric citrate-functionalized ciprofloxacin conjugates have been synthesized and their antimicrobial activities against a panel of clinically-relevant bacteria have been determined. Cellular uptake mechanisms were investigated using wild-type and ompF deletion strains of Escherichia coli K-12.
- Md-Saleh, Siti R,Chilvers, Emily C.,Kerr, Kevin G.,Milner, Stephen J.,Snelling, Anna M.,Weber, Jan P.,Thomas, Gavin H.,Duhme-Klair, Anne-Kathrin,Routledge, Anne
-
scheme or table
p. 1496 - 1498
(2009/11/30)
-
- CHELATING SILICON-BASED POLYMERS
-
The present invention relates to novel silicon-based polymers, particularly silicon-based polymers having citrate groups, and their use as chelating agents, for forming nanostructures, as surfactants, as reducing agents and as stabilizers.
- -
-
Page/Page column 30
(2008/06/13)
-
- ZrOCl2·8H2O: An efficient, cheap and reusable catalyst for the esterification of acrylic acid and other carboxylic acids with equimolar amounts of alcohols
-
Esterifications of carboxylic acids with equimolar amount of alcohols could be efficiently catalyzed by ZrOCl2·8H2O. Acrylate esters were obtained in good yields under solvent-free conditions at ambient temperature. The esterification of other carboxylic acids with alcohols also proceeded at ambient temperature or at 50°C to afford esters in high yields. If the esterification was performed in toluene under azeotropic reflux conditions to remove water, both the catalytic activity of ZrOCl 2·8H2O and the rate of esterification could be increased greatly. Furthermore, in the present catalytic system, the esters could be easily separated from the reaction mixtures and the catalyst could be easily recovered and reused.
- Sun, Hong-Bin,Hua, Ruimao,Yin, Yingwu
-
p. 263 - 271
(2007/10/03)
-
- PROCESS FOR THE PREPARATION OF DIALKYL 3-OXOGLUTARATES
-
This invention relates to a process for the preparation of 3-oxoglutarates of general formula (I), wherein R stands for methyl or ethyl. Said process comprises reacting citric acid of the formula (II) or the monohydrate thereof with chlorosulphonic acid in a lower chlorinated aliphatic hydrocarbon and reacting the intermediate thus obtained with methanol or ethanol by applying a ratio of lower chlorinated aliphatic hydrocarbon to chlorosulphonic acid in the range of 0,1:1 to 1:1 by volume and carrying out the addition of citric acid to the mixture of chlorosulphonic acid and lower aliphatic hydrocarbon at a rate of 1 - 2 kg/minute. The dialkyl 3-oxoglutarates are valuable pharmaceutical intermediates.
- -
-
-
- A selective method for the preparation of aliphatic methyl esters in the presence of aromatic carboxylic acids
-
2,2-Dimethoxypropane, methanol and a catalytic amount of HCl selectively esterify aliphatic carboxylic acids, in the presence of aromatic carboxylic acids, at room temperature and in high yields.
- Rodriguez,Nomen,Spur,Godfroid
-
p. 8563 - 8566
(2007/10/03)
-
- Synthesis and characterisation of tin(II) and tin(IV) citrates
-
A series of tin(II) citrates, SnM(C6H4O7) (M = Sn or Zn) and SnMM′(C6H4O7) (M = M′ = Na, K or NH4; M = NMe4, M′ = H) and related monotin(II) salts of 1,5-dimethyl and 1,5-di-n-butyl citrate have been synthesized and characterised by spectroscopic methods (IR, 1H, 13C, 119Sn NMR, 119Sn Moessbauer). The crystal structures of dimeric tin(II) 1,5-dimethyl citrate and an oxidation product, Sn(NMe4)2(C6H5O7) 2·3.5H2O, have also been determined.
- Deacon, Paul R.,Mahon, Mary F.,Molloy, Kieran C.,Waterfield, Phillip C.
-
p. 3705 - 3712
(2007/10/03)
-
- 2-Hydroxy-1,2,3-propanetricarboxylic acid 2-methyl ester, a new natural product from Rhus parviflora: A simple achiral molecule having both enantiotopic and diastereotopic hydrogens
-
A new natural citric acid derivative identified as 2-hydroxy-1,2,3-propanetricarboxylic acid 2-methyl ester ( citric acid 2-methyl ester) (1) has been isolated from the fruits of Rhus parviflora.The structure has been established from its 1H, 13C NMR and mass spectral data and elemental analysis and also through its dimethyl ester shown to be trimethyl citrate (2).Compounds 1 and 2 provide interesting examples of simple achiral molecules having three adjacent prochiral centres and two enantiotopic pairs of diastereotopic geminal hydrogens.
- Talapatra, Bani,Bhaumik, Asis,Talapatra, Sunil K.
-
p. 1292 - 1294
(2007/10/02)
-
- Process for the preparation of citric acid esters, citric acid or citric acid salts
-
A process is provided for making a triester of citric acid wherein the cyanohydrin of an acetone dicarboxylic acid diester is reacted with 1 to 3 molar equivalents of an aliphatic alcohol having 1 to 4 carbon atoms and at least two molar equivalents of anhydrous hydrogen chloride in an inert halogenated organic solvent for the cyanohydrin diester at not above 50°C. to form an imino ether, removing excess hydrogen chloride, adding water to form a two-phase system, separating the organic and water phases and recovering the resulting triester from the organic phase. The triester may be hydrolyzed into citric acid or a salt of citric acid in an acid or alkaline medium.
- -
-
-
