- Insight into the isoelectronic character of azomethines and vinylenes using representative models: A spectroscopic and electrochemical study
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A series of azomethine and vinylene dyad and triad analogues were prepared. Their absorbance, fluorescence, and redox properties were examined experimentally and theoretically using density functional theory (DFT) calculations. These measurements were done to determine the effect of the heteroatom of the azomethine relative to its all-carbon counterpart and to assess the isoelectronic character of the two bonds. The orientation of the azomethine was found to have little effect on the absorbance, fluorescence, and electrochemical properties. In contrast, the spectral and electrochemical properties were highly contingent on the electronic groups and degree of conjugation. The spectral properties could be tuned 200 nm across the visible region. More importantly, the heteroatom in the conjugated bond was found to give rise to only a 20 nm bathochromic shift in the absorbance and fluorescence spectra. The fluorescence quantum yield (ΦFl) of the vinylene derivatives varied between 5% and 20% with fluorescence quenching occurring by photoisomerization from the E to Z isomers. In contrast, the fluorescence of the analogous azomethine derivatives was completely quenched. The collective spectroscopic and electrochemical ab initio DFT data additionally confirmed that the azomethine and its analogous vinylene are isoelectronic. It was also found that a conjugated thiophene vinylene dyad with primary amines in the α,α′-positions could be prepared and isolated. The compound was stable under aerobic conditions providing electron withdrawing (either ester or nitrile) groups were located in the adjacent positions.
- Bolduc, Andreanne,Al Ouahabi, Abelaziz,Mallet, Charlotte,Skene
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- A novel cyanoacrylate-based matrix excipient in HPMCP capsules forms a sustained intestinal delivery system for orally administered drugs with enhanced absorption efficiency
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Patients prefer oral drug delivery due to its convenience and noninvasiveness. Nevertheless, a multitude of potentially clinically important drugs will not reach the market or achieve their full potential, due to their low bioavailability and instability in gastric acid. In this study, a novel oral drug delivery system based on poly-cyanoacrylate [a polymer of 2-(2-methoxyethoxy)ethyl-2-cyanoacrylate (MECA)] and hydroxypropyl methylcellulose phthalate (HPMCP) was developed and shown to permit intestinal targeting and sustained drug release. Aspirin [acetylsalicylic acid (ASA)] was selected as a model drug for atherosclerosis treatment. It was physically dissolved in liquid MECA, and the ASA-MECA matrix was then polymerized into a solid drug-loading depot in an HPMCP shell. The delivery of the drug depot in the intestine was achieved with the HPMCP shell; then the polymerized MECA (polyMECA) provided sustained drug release. The polyMECA excipient was not absorbed by the intestine due to its high molecular weight; a fluorescein-labeled assay indicated that it was excreted completely in feces after drug release. The formulation, ASA-polyMECA-HPMCP, showed good intestinal targeting and sustained drug releasein vitroandin vivo. Pharmacokinetic studies indicated that this formulation improved the bioavailability of ASA relative to commercially available controls. ASA-polyMECA-HPMCP showed desirable anti-atherosclerosis efficacy in a rabbit model, with significant enhancement of atheromatous lesion stability. Biosafety tests proved the low toxicity of ASA-polyMECA-HPMCP and the polyMECA matrix. We believe that this work has provided a practical and biocompatible system for sustained intestinal drug delivery that can be applied broadly with various drugs for specific therapeutic aims.
- Song, Liya,Chen, Pengfei,Yu, Jin,Han, Xiaolu,Hua, Yabing,Liu, Shan,Pang, Bo,Gao, Jing,Ma, Jiahua,Xu, Liang
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- Magnetically recoverable AlFe/Te nanocomposite as a new catalyst for the facile esterification reaction under neat conditions
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In this work, a new Fe3O4/AlFe/Te nanocomposite was synthesized by a one-step sol–gel method. The Fe3O4 magnetic nanoparticles (MNPs) were prepared and then mixed with aluminum telluride (Al2Te3) in an alkali medium to produce the desired catalyst. After characterization of the Fe3O4/AlFe/Te nanocomposite by SEM, TEM, EDS, XRD, and ICP analyses, it was used in the esterification reaction. This heterogeneous catalyst showed high catalytic activity in the esterification of commercially available carboxylic acids with various alcohols to produce the desired esters at high conversions under neat conditions. The Fe3O4/AlFe/Te nanocomposites were separated from the reaction mixture via an external magnet and re-used 8 times without significant loss of catalytic activity.
- Alavi, Seyed Jamal,Sadeghian, Hamid,Seyedi, Seyed Mohammad,Eshghi, Hossein,Salimi, Alireza
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- PROCESS FOR PREPARING ELECTRON DEFICIENT OLEFIN PRECURSORS
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This invention relates to a process for producing electron deficient olefin precursors, such as 2-cyanoacetates, using an acid catalyzed esterification reaction.
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Paragraph 0046; 0047
(2018/07/22)
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- PROCESS FOR PREPARING ELECTRON DEFICIENT OLEFINS
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This invention relates to a process for preparing electron deficient olefins, such as 2-cyanoacrylates, using an acid catalyzed two-step process including an esterification reaction followed by a Knoevenagel condensation reaction.
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Paragraph 0065
(2018/07/29)
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- PROCESS FOR PREPARING ELECTRON DEFICIENT OLEFIN PRECURSORS
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This invention relates to a process for producing electron deficient olefin precursors, such as 2-cyanoacetates, using an acid catalyzed transesterification reaction.
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Paragraph 0045
(2018/07/29)
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- PROCESS FOR PREPARING ELECTRON DEFICIENT OLEFINS
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This invention relates to a process for preparing electron deficient olefins, such as 2-cyanoacrylates, using an acid catalyzed two-step process including a transesterification reaction followed by a Knoevenagel condensation reaction.
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Paragraph 0065
(2018/07/29)
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- One-pot esterification and amide formation via acid-catalyzed dehydration and ritter reactions
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Esterification of carboxylic acid is achieved using acetonitrile as a water trap. Water liberated during esterification is consumed in cyanide hydrolysis, thereby driving the esterification to completion. Substrates having carboxylic acid and nitrile groups undergo intramolecular dehydration and rehydration to amido esters in the absence of acetonitrile. Cyano acids also undergo esterification and Ritter reaction in one pot when excess alcohol is used. For the first time, we have observed an interesting Ritter reaction of primary alcohols, leading to ester amide product in one pot. [Supplementary materials are available for this article. Go to the publisher's online edition of Synthetic Communications for the following free supplemental resource(s): Full experimental and spectral details.]
- Dawar, Pankaj,Raju, M. Bagavan,Ramakrishna, Ramesha Andagar
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supporting information
p. 836 - 846
(2014/03/21)
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- Borontrifluoride etherate promoted one-pot conversion of nitriles to esters
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One-pot borontrifluoride etherate promoted transformation of nitriles to esters was achieved by heating in corresponding alcohol as a reactant and solvent.
- Jayachitra,Yasmeen,Srinivasa Rao,Ralte, Samuel L.,Srinivasan,Singh
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p. 3461 - 3466
(2007/10/03)
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- Process for preparing cyanoacetamide
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Cyanoacetamide is prepared without additional catalyst by esterification of crude cyanoacetic acid with a monohydric alcohol which forms an azeotrope with water and has 4 to 10 carbon atoms, reacting the resulting ester with ammonia in the presence of a basic catalyst to give cyanoacetamide, and work-up by a mechanical separating operation and a thermal treatment.
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- Preparation of alkyl cyanoacetates
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A process for the preparation of C4 -C10 alkyl cyanoacetates by the reaction of cyanoacetic acid with C4 -C10 alkanols at a temperature of from 35° to 150° C. and under a pressure of from 70 to 1013 mbar, in the presence of catalytic amounts of acid, while a C4 -C10 alkanol/water azeotrope is separated during the reaction.
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