- Method for continuous-flow preparation of 2,2-dimethylmalonic acid
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The invention provides a method for continuous-flow preparation of 2,2-dimethylmalonic acid. According to the method, a micro-channel reactor is utilized, a 2,2-dimethyl propylene glycol solution is used as a material 1, nitric acid is used as a material 2, and the materials are introduced into the micro-channel reactor for continuous-flow synthesis of 2,2-dimethylmalonic acid, wherein the reaction temperature is 30-100 DEG C, and the reaction time is 20-100 s. Compared with a conventional tank reactor in the prior art, the method provided by the invention has the advantages that the reactiontime is greatly shortened, mass transfer and heat transfer are uniform, the amplification effect is avoided, and the yield is improved to a certain extent compared with a tank reaction; more importantly, a liquid holding volume of the method is small, so the potential risk of nitric acid oxidation is greatly reduced; and the safety and operability of the method are improved.
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Paragraph 0013
(2020/11/25)
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- Preparation and Characterisation of a Bis-μ-Hydroxo-NiIII 2 Complex
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Hydroxide-bridged high-valent oxidants have been implicated as the active oxidants in methane monooxygenases and other oxidases that employ bimetallic clusters in their active site. To understand the properties of such species, bis-μ-hydroxo-NiII 2 complex (1) supported by a new dicarboxamidate ligand (N,N′-bis(2,6-dimethyl-phenyl)-2,2-dimethylmalonamide) was prepared. Complex 1 contained a diamond core made up of two NiII ions and two bridging hydroxide ligands. Titration of the 1 e? oxidant (NH4)2[CeIV(NO3)6] with 1 at ?45 °C showed the formation of the high-valent species 2 and 3, containing NiIINiIII and NiIII 2 diamond cores, respectively, maintaining the bis-μ-hydroxide core. Both complexes were characterised using electron paramagnetic resonance, X-ray absorption, and electronic absorption spectroscopies. Density functional theory computations supported the spectroscopic assignments. Oxidation reactivity studies showed that bis-μ-hydroxide-NiIII 2 3 was capable of oxidizing substrates at ?45 °C at rates greater than that of the most reactive bis-μ-oxo-NiIII complexes reported to date.
- Spedalotto, Giuseppe,Gericke, Robert,Lovisari, Marta,Farquhar, Erik R.,Twamley, Brendan,McDonald, Aidan R.
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supporting information
p. 11983 - 11990
(2019/08/26)
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- Photodegradation of Myrigalone A, an Allelochemical from Myrica gale: Photoproducts and Effect of Terpenes
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This study investigated the environmental fate of myrigalone A, a light absorbing natural herbicide found on leaves and fruits of Myrica gale. Myrigalone A was irradiated in water and as a dry solid deposit to simulate reactions on leaves, alone and in the presence of the terpenes generated by Myrica gale. The phototransformation was fast (t1/2 = 35 min in water). Analyses by liquid chromatography coupled to high resolution orbitrap electrospray mass spectrometry (MS) and gas chromatography-MS revealed the formation of 11 photoproducts in water and solid and 9 in gaseous phase. Some were detected in the leaf glands and oil covering the fruits of Myrica gale, which suggested that photodegradation occurred in the field. Moreover, myrigalone A photoinduced the oxidation of terpenes that in turn protected it against photolysis. This highlights the need for additional research on the effect of terpenes on the photodegradation of pesticides on vegetation.
- Khaled, Amina,Sleiman, Mohamad,Darras, Etienne,Trivella, Aurélien,Bertrand, Cédric,Inguimbert, Nicolas,Goupil, Pascale,Richard, Claire
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p. 7258 - 7265
(2019/07/08)
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- Design of bisquinolinyl malonamides as Zn2+ ion-selective fluoroionophores based on the substituent effect
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A series of malonamides possessing two quinoline moieties were synthesized and characterized as fluoroionophores for the Zn2+ ion. We focused on the relationship between the substituents introduced to the C2-position of the malonamides and their Zn2+ ion-selectivity, exploiting the structural effect of the substituents in the design of the fluoroionophores with high selectivity. The substituents introduced to the malonamides were the methyl, benzyl and naphthalenylmethyl groups. In dimethyl sulfoxide solvent, all substituted bisquinolinyl malonamides showed excellent fluorescence sensing for the Zn2+ ion, while unsubstituted bisquinolinyl malonamide 1 displayed ratiometric sensing for the Co2+ ion. N,N′-Bis(8-quinolyl)-2-methyl-2-naphthalenylmethyl malonamide 4 exhibited the highest Zn2+ ion-selectivity against the Cd2+ ion. Although the substituents introduced into the C2-position are spatially distant from the quinoline recognition moiety, this study indicated that they greatly influenced the ion selectivities of the bisquinolinyl malonamides. Furthermore, it was demonstrated that visible fluorescence analyses could be performed on malonamide 4.
- Moriuchi-Kawakami, Takayo,Kawata, Keita,Nakamura, Sho,Koyama, Yoshiaki,Shibutani, Yasuhiko
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p. 9805 - 9813
(2015/01/09)
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- Microwave assisted hydrolysis of Meldrum's acid derivatives and decarboxylation of derived malonic acids
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Microwave induced hydrolysis of alkyl Medrum's acids and decarboxylation of derived malonic acids using poly-4-vinylpyridine as a catalyst gives high yields of carboxylic acids in a short time.
- Helavi,Solabannavar,Desai,Mane
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p. 174 - 175
(2007/10/03)
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- Process for preparing malonic acid and alkylmalonic acids
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Malonic acid and alkylmalonic acids are prepared by a process of acid-catalyzed saponification of malonic acid esters, which comprises: contacting an aqueous mixture of the ester II with an acid ion exchanger containing sulfonic acid groups at from 30°-100° C. and from 40-1000 mbar according to the following scheme: STR1 where R1 =H, CH3, R2 =H, CH3 or R1 +R2 =--CH2 --CH2 --and R3 =CH3, C2 H5, C3 H7, C(CH3)3 ; distilling off the alcohol R3 OH which is formed; separating the water, with the aid of organic solvents, from the malonic acid or alkylmalonic acid product; and then isolating the product by crystallization.
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- RETROVIRAL PROTEASE INHIBITORS
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Urea-containing hydroxyethylamine peptide compounds are effective as retroviral protease inhibitors, and in particular as inhibitors of HIV protease.
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- Ligandgesteuerte Ringkontraktion von Nickela-Fuenf- in Vierringkomplexe-neuartige Startsysteme fuer die praeparative Chemie
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Nickela-compounds with a five-membered ring, 4, are formed on Ni0 from CO2 and alkenes in the presence of the heterodifunctional ligand (cyclo-C6H11)2PCH2-CH2-2-pyridyl (2).A ring contraction occurs on addition of a promotor, such as BeCl2 or on heating.The greater reactivity of the nickela-complex with a four-membered ring, 6, can be used in the former reactions with CO2, CO or CH2=CH2.Such a sequence of reactions can be employed for the catalytic reaction of ethene with acrylic anilide on a (C6H11)3P/Ni0 system.
- Hoberg, Heinz,Ballesteros, Alfredo,Sigan, Andrei,Jegat, Corine,Baerhausen, Dieter,Milchereit, Armin
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p. C23 - C29
(2007/10/02)
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- The Nitration of 3,4,5,6-Tetramethylbenzene-1,2-dicarbonitrile, 2,3,5,6-Tetramethylbenzonitrile, 1,2,3-Trimethyl-4,6-dinitrobenzene and 1,2,4,5-Tetramethyl-3,6-dinitrobenzene. Methyl Migrations Following ipso-Substitution
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Nitration of 3,4,5,6-tetramethylbenzene-1,2-dicarbonitrile (1a) gives epimeric pairs of dinitro ketones (6a) and (7a), and hydroxy ketones (9) and (10), in addition to the benzyl nitrate (4) and phthalide (5).Nitration of 2,3,5,6-tetramethylbenzonitrile (11) gives the epimeric dinitro ketones (15) and (16), in addition to the nitrobenzonitrile (12) and the nitrophthalide (13).Nitration of 1,2,3-trimethyl-4,6-dinitrobenzene (17) gives dimethylpropanedioic acid (23), the dinitrobenzoic acid (24), and the hydroxy dienone (25).Nitration of 1,2,4,5-tetramethyl-3,6-dinitrobenzene (18) gives dimethylpropanedioic acid (23), the dinitrobenzoic acid (26), and the nitro dicarboxylic acid (27).The formation of compounds (6a), (7a), (9), (10), (15), (16), (23) and (27) all involve methyl migrations following nitronium ion attack ipso to the migrating methyl group.X-Ray structure determinations are reported for compounds (6a), (9) and (15).
- Hartshorn, Michael P.,Readman, Jennifer M.,Robinson, Ward T.,Sies, Christiaan W.,Wright Graeme J.
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p. 373 - 386
(2007/10/02)
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- The E1cb Route for Ester Hydrolysis; Volumes of Activation as an Additional Criterion of Mechanism
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Hydrolyses of esters which possess an acidic proton at the α or vinylogous position can, in principle, hydrolyse by the E1cb route via a ketenoid intermediate.To the kinetic evidence for such a mechanism in the hydrolyses of 4-hydroxybenzoates, malonates, acetoacetates and fluorenecarboxylates is now added the further criterion of volumes of activation.Values of ΔV(excit.) for reactions proceeding by the E1cb route are positive and contrast with the negative values associated with hydrolyses by the more usual BAc2 mechanism.
- Isaacs, Neil S.,Najem, Tariq S.
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p. 557 - 562
(2007/10/02)
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- Ketene. Part 26. The Reactions of 3,4-Dihydroisoquinoline N-Oxide with Ketenes, and an Attempted Synthesis of 3,4-Dihydro-3,3-dimethylquinoline N-Oxide
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3,4-Dihydroisoquinoline N-Oxide reacts with dimethylketene to form a 1:2 adduct (8) in addition to compounds (6) and (7).With cyano-t-butylketene and ethoxycarbonyl-t-butylketene the adducts (9a) and (9b) are formed. 3,3-Dimethyl-1,2,3,4-tetrahydroquinoline (21a) has been synthesized, but attempts to convert this into the nitrone (20b) were unsuccessful.
- Evans, Andrew R.,Martin, Russell,Taylor, Giles A.,Yap, C. H. Maurice
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p. 1635 - 1640
(2007/10/02)
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- Bis-esters of dicarboxylic acids with amoxicillin and certain hydroxymethylpenicillanate 1,1-dioxides
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Antibacterial bis-esters of 1,4-cyclohexanedicarboxylic acids and alkane dicarboxylic acids wherein the ester moieties are derived from different alcohols; one alcohol being hydroxymethylpenicillanate 1,1-dioxide, or the 6-beta-hydroxymethyl or the 6-alpha-aminomethyl derivative thereof; and the other being 6-[D-(2-amino-2-(p-hydroxyphenyl)acetamido)]penicillanic acid (amoxicillin); and pharmaceutically acceptable salts thereof; a method for the use of said esters and their salts, and methods for their preparation.
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- HYDROLYSIS OF BARBITURIC ACID DERIVATIVES.PART IV. HYDROLYSIS OF DERIVATIVES WITHOUT SHIELDING STERIC EFFECT
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Kinetics and products of hydrolysis of the monoanion form of three C-5 spirobarbiturates with 4-, 5- and 6-membered rings and 5,5-dimethylbarbituric acid have been investigated.The pKa values of these compounds were determined and the analysis of C=O stretching modes has been carried out.The effects of substituents at the C-5 carbon atom of barbituric acids on the rates of hydrolysis are discussed.
- Mokrosz, Jerzy,Bojarski, Jacek
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p. 491 - 500
(2007/10/02)
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- Modified isocyanate compositions
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A process for the production of a modified isocyanate by reacting a composition containing carbodiimide groups and free isocyanate groups with a diester of an aliphatic dicarboxylic acid in the presence of oxalic or formic acid. The process permits the production of liquid forms of diphenylmethane diisocyanate useful in the manufacture of polyurethanes.
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