616-02-4Relevant articles and documents
Addition of a silyl ketene acetal to α,β-unsaturated cyclic anhydrides
Gnaneshwar, Rudhramyna,Sivaram, Swaminathan
, p. 2353 - 2363 (2010)
Addition of [1-methoxy-2 methyl-1-propenyl)-oxy] trimethylsilane (MTS) to unsymmetrical,-unsaturated cyclic anhydrides (namely, itaconic anhydride and citraconic anhydride) as well as symmetrical anhydrides (namely, maleic anhydride and 2,3-dimethylmaleic anhydride) was investigated. Itaconic anhydride isomerizes to citraconic anhydride in the presence of MTS. In the presence of Lewis acid catalysts (Yb(OTf)3/CH2Cl2), MTS adds to itaconic anhydride at room temperature in a 1,4-fashion. 1,2-Addition is the preferred pathway with both 2,3-dimethyl maleic anhydride and citraconic anhydride. Copyright Taylor & Francis Group, LLC.
FRAGRANCE MIXTURE
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Paragraph 0317-0321; 0335-0339, (2020/01/24)
A fragrance mixture and its applications, in particular perfume oils, cosmetic agents, application agents or washing and cleaning agents, containing a sensory effective amount of (i) (E)-2-methyl-but-2-endicarboxylic acid diethyl ester, (ii) (Z)-2-methyl-but-2-endicarboxylic acid diethyl ester or (iii) 2-methylenebutanedicarboxylic acid diethyl ester and mixtures thereof and analogous esters derived from these compounds and mixtures.
Bis (citraconoyl imino) hydrocarbon, preparation method thereof and application thereof as anti-reversion agent
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Paragraph 0025; 0028; 0031; 0034; 0037; 0040;, (2020/03/09)
The invention discloses a bis (citraconoyl imino) hydrocarbon as well as a preparation method and application thereof as an anti-reversion agent. The bis (citraconoyl imino) hydrocarbon molecules contain two structures of citraconoyl imino and methylene chain segments, can play a role in resisting reversion and enhancing the flexing resistance of a rubber material at the same time, is a very goodanti-reversion agent, and can effectively overcome the defects that the flexing resistance of rubber is reduced, and chunking and chipping occur due to PK900. The preparation method is simple in process and easy to operate, the obtained product is high in yield, high in purity, odorless and free of blooming, the direction and requirements for developing low-odor or odorless tires in the future canbe met, and the preparation method has good economic and social benefits and wide market prospects.
Synthesis of the Bicyclic Lactone Core of Leonuketal, Enabled by a Telescoped Diels–Alder Reaction Sequence
Grant, Phillip S.,Brimble, Margaret A.,Furkert, Daniel P.
, p. 1128 - 1135 (2018/09/06)
The Diels–Alder cycloaddition reaction has become established as a fundamental approach for the preparation of complex natural products; however, successful application of the intermolecular Diels–Alder cycloaddition reaction to the synthesis of particularly congested scaffolds remains surprisingly problematic. Inspired by the terpenoid spiroketal natural product leonuketal, a challenging telescoped reaction sequence has been realized to access the core [2.2.2]-bicyclic lactone ring system and its [3.2.1] isomer. Our four-step, protecting-group-free process required detailed investigation to circumvent the problems of adduct fragmentation and intermediate instability. Successful solution of these practical issues, along with unambiguous structural determination of the target structures, provide useful insights that will facilitate future applications of the Diels–Alder cycloaddition reaction to challenging, highly congested molecular scaffolds and ongoing synthetic efforts towards this natural product.
A 2 - methyl maleic anhydride synthesis method
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Paragraph 0013; 0014; 0015; 0016; 0017; 0018; 0019; 0020, (2018/04/03)
The invention relates to a novel synthesis method of 2-methyl maleic anhydride, which comprises the following steps: adding a catalyst into itaconic acid, mixing, heating to 160-200 DEG C, keeping the temperature to react for 3-5 hours, continuously and completely distilling off water generated by reaction in the reaction process, and carrying out reduced pressure distillation to obtain a light yellow oily liquid which is the 2-methyl maleic anhydride. By adopting the technique, the method is simple to operate, has the advantages of low technological conditions low facility request and high reaction yield, and is suitable for industrial production. The yield of the obtained target product 2-methyl maleic anhydride is 85% above, and the purity can reach 98%.
Heterogeneous catalysts for the cyclization of dicarboxylic acids to cyclic anhydrides as monomers for bioplastic production
Rashed, Md. N.,Siddiki,Ali, Md. A.,Moromi, Sondomoyee K.,Touchy, Abeda S.,Kon, Kenichi,Toyao, Takashi,Shimizu, Ken-Ichi
, p. 3238 - 3242 (2017/07/28)
Cyclic anhydrides, key intermediates of carbon-neutral and biodegradable polyesters, are currently produced from biomass-derived dicarboxylic acids by a high-cost multistep process. We present a new high-yielding process for the direct intramolecular dehydration of dicarboxylic acids using a reusable heterogeneous Lewis acid catalyst, Nb2O5·nH2O. Various dicarboxylic acids, which can be produced by a biorefinery process, are transformed into the corresponding cyclic anhydrides as monomers for polyester production. This method is suitable for the production of renewable polyesters in a biorefinery process.
Preparation method of citraconic anhydride
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Paragraph 0015; 0016; 0017; 0018; 0019; 0020; 0021, (2017/07/19)
The invention relates to the technical field of citraconic anhydride production, and particularly discloses a preparation method of citraconic anhydride. The preparation method of citraconic anhydride uses itaconic acid as the raw material, and is characterized by comprising the following steps: putting itaconic acid, an alkali metal catalyst and a solvent in a reactor, heating in a vacuum to perform water diversion reaction, carrying out primary reduced pressure distillation recovery, adding the recovered product into the reactor, adding one half of the itaconic acid added for the first time and an equal amount of the catalyst, heating in a vacuum to perform water diversion reaction, carrying out secondary reduced pressure distillation, heating, and collecting the product, thereby obtaining the citraconic anhydride. The method has the advantages of simple reaction, high product yield, high product purity, wide catalyst sources, low price, high reaction speed, reusable recovered solution and low production cost.
MoO3-TiO2 synergy in oxidative dehydrogenation of lactic acid to pyruvic acid
Liu, Kaituo,Huang, Xiaoming,Pidko, Evgeny A.,Hensen, Emiel J. M.
, p. 3014 - 3022 (2017/07/15)
An efficient catalytic process for the oxidative dehydrogenation of biomass-derived lactic acid by earth-abundant MoO3/TiO2 mixed oxide catalysts is presented. A series of MoO3/TiO2 materials with varied MoO3 loadings were prepared and their performance in the aerobic and anaerobic conversion of lactic acid was evaluated. A strong synergistic effect between MoO3 and TiO2 components of the mixed oxide catalyst was observed. Optimum catalysts in terms of activity and pyruvic acid selectivity can be obtained by ensuring a high dispersion of MoOx species on the titania surface. Mo-oxide aggregates catalyze undesired side-reactions. XPS measurements indicate that the redox processes involving supported Mo ions are crucial for the catalytic cycle. A mechanism is proposed, in which lactic acid adsorbs onto basic sites of the titania surface and is dehydrogenated over the Mo=O acid-base pair of a vicinal tetrahedral Mo site. The catalytic cycle closes by hydrolysis of surface pyruvate and water desorption accompanied by the reduction of the Mo center, which is finally oxidized by O2 to regenerate the initial active site. Under anaerobic conditions, a less efficient catalytic cycle is established involving a bimolecular hydrogen transfer mechanism, selectively yielding propionic and pyruvic acids as the major products. The optimum catalyst is 2 wt% MoO3/TiO2 predominantly containing tetrahedral Mo species. With this catalyst the oxidative conversion of lactic acid at 200 °C proceeds with a selectivity of ca. 80% to pyruvic acid. The pyruvic acid productivity is 0.56 g g-1 h-1.
Asymmetric hydrogenation of maleic anhydrides catalyzed by Rh/bisphosphine-thiourea: efficient construction of chiral succinic anhydrides
Han, Zhengyu,Wang, Rui,Gu, Guoxian,Dong, Xiu-Qin,Zhang, Xumu
supporting information, p. 4226 - 4229 (2017/04/21)
Asymmetric hydrogenation of various 3-substituted maleic anhydrides catalyzed by Rh/bisphosphine-thiourea (ZhaoPhos) under mild conditions was successfully developed. A wide range of 3-alkyl and 3-aryl maleic anhydrides were hydrogenated well to provide the desired products 3-substituted succinic anhydrides in one hour with excellent results (full conversions, up to 99% yield, 99% ee, 3000 TON). Importantly, we developed a creative and efficient synthetic route to construct the key intermediate of the hypoglycemic drug mitiglinide through our catalytic system.
Anti-anti-sulfuration recovery agent 1,3-bis ( lemon rice polishings imide methyl) benzene preparation method
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Paragraph 0015; 0016; 0017; 0018; 0019, (2017/05/23)
The invention discloses a method for preparing anti-vulcanization reversion agent 1,3-bis(citraconimidomethyl)benzene. The method comprises the following steps: mixing itaconic acid, dimethylsulfoxide and disodium hydrogen phosphate according to a ratio, raising the temperature to be 175-195 DEG C, keeping the temperature and reacting for 1-2 hours, removing a solvent, subsequently dehydrating so as to prepare liquid 2-methyl maleic anhydride, further mixing 2-methyl maleic anhydride, m-xylylenediamine, xylene and pyridine according to a ratio, performing reaction under reflux for 3-4 hours at 120 DEG C, distilling under reduced pressure to obtain a crude product, finally recrystallizing the crude product, cooling down, filtering and drying so as to obtain 1,3-bis(citraconimidomethyl)benzene. As no acetic anhydride is used, no acetic acid is generated in the process, so that corrosion on equipment and environmental pollution are greatly reduced; in addition, the product prepared by using the method is high in yield and good in purity, and no equipment needs to be additionally arranged, so that the method is high in practicability.
