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Carboxylic acid

About: Carboxylic acid is a research topic. Over the lifetime, 48544 publications have been published within this topic receiving 605696 citations.


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PatentDOI
TL;DR: The cross-linked gels were stable in neutral or strongly acidic aqueous media, but the cross-linking process was reversed in basic aqueously solutions of excess monovalent cations.
Abstract: Hexachlorocyclotriphosphazene and poly(dichlorophosphazene) react with the sodium salt of ethyl p-hydroxybenzoate to give small molecule cyclic and high polymeric phosphazenes with aryloxy ester side groups; reaction of these compounds with potassium tert-butoxide brings about complete hydrolysis of the ester groups to yielding aqueous media-soluble, carboxylic acid bearing cyclic and high polymeric phosphazenes; the carboxylic acid bearing high polymer formed ionic cross-links when treated in aqueous media with salts of di- or trivalent cations yield hydrogels and membranes. The cross-linked gels were stable in neutral or strongly acidic aqueous media, but the cross-linking process was reversed in basic aqueous solutions of excess monovalent cations.

156 citations

Journal ArticleDOI
TL;DR: A synthetic strategy for direct access to both alkyl and acyl radicals from these ubiquitous functional groups via photoredox catalysis, which enables the reduction of aromatic and aliphatic carboxylic acids to the corresponding aldehydes with exceptional chemoselectivity.
Abstract: Despite the prevalence of alcohols and carboxylic acids as functional groups in organic molecules and the potential to serve as radical precursors, C–O bonds remain difficult to activate. We report a synthetic strategy for direct access to both alkyl and acyl radicals from these ubiquitous functional groups via photoredox catalysis. This method exploits the unique reactivity of phosphoranyl radicals, generated from a polar/SET crossover between a phosphine radical cation and an oxygen-centered nucleophile. We show the desired reactivity in the reduction of benzylic alcohols to the corresponding benzyl radicals with terminal H atom trapping to afford the deoxygenated products. Using the same method, we demonstrate access to synthetically versatile acyl radicals, which enables the reduction of aromatic and aliphatic carboxylic acids to the corresponding aldehydes with exceptional chemoselectivity. This protocol also transforms carboxylic acids to heterocycles and cyclic ketones via intramolecular acyl radic...

156 citations

Journal Article
TL;DR: In this article, the Fischer Esterification method was used to remove the catalyst from multiwalled carbon nanotubes (MWCNTs) and introduce carboxylic acid groups onto the surface of MWCNTs.
Abstract: Multiwalled carbon nanotubes (MWCNTs) were functionalized by different functional groups via the Fischer Esterification method. Nitric acid treatment was first used to remove the catalyst from MWCNTs and introduce carboxylic acid groups onto the surface of MWCNTs. These carboxylic groups were used as reaction precursors in the functionalization. Four functional groups―phenol, dodecylamine, 1-octadecanol, and polyethylene glycol―were successfully covalently attached to MWCNTs via amidation or esterification. The functionalized MWCNTs were then characterized by Fourier Transform Infrared (FTIR) spectroscopy, thermal analysis techniques, thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). The MWCNTs attached to the organofunctional moieties have greater versatility for further utilization in different application fields such as biology, nanocomposites, water treatment, petroleum, and petrochemical technologies. Key words : functionalized CNTs, Fischer Esterification, carboxylic acid groups, phenol, dodecylamine, 1-octadecanol, polyethylene glycol

156 citations

Journal ArticleDOI
08 Jan 2015-Nature
TL;DR: The use of this catalyst is demonstrated in the synthesis of the naturally occurring anti-tumour agent neopeltolide and in a single-step stereoselective gram-scale conversion of a renewable feedstock (oleic acid) to an anti-fungal agent, indicating that its utility may extend beyond Z-selective processes.
Abstract: A ruthenium–disulfide catalyst is presented that is effective in generating compounds of medical and industrial utility (alcohols that contain a phenol, an aldehyde, or a carboxylic acid) by room-temperature, inexpensive, high-yielding cross-metathesis. Catalytic olefin metathesis is one of the most widely used reactions in synthetic organic chemistry, but its utility has been limited by the dearth of chemical transformations that directly generate acyclic Z allylic alcohols. In this manuscript, the authors present an electronically modified ruthenium-disulphide catalyst that is uniquely effective in generating compounds of medical and industrial utility (alcohols containing a phenol, an aldehyde or a carboxylic acid) by room-temperature, inexpensive, high-yielding cross-metathesis. The efficiency of the catalyst is demonstrated in the synthesis of naturally occurring antitumour agent neopeltolide and a single-step stereoselective gram-scale conversion of a renewable feedstock to an antifungal agent. Olefin metathesis catalysts provide access to molecules that are indispensable to physicians and researchers in the life sciences1,2. A persisting problem, however, is the dearth of chemical transformations that directly generate acyclic Z allylic alcohols, including products that contain a hindered neighbouring substituent or reactive functional units such as a phenol, an aldehyde, or a carboxylic acid. Here we present an electronically modified ruthenium–disulfide catalyst that is effective in generating such high-value compounds by cross-metathesis. The ruthenium complex is prepared from a commercially available precursor and an easily generated air-stable zinc catechothiolate. Transformations typically proceed with 5.0 mole per cent of the complex and an inexpensive reaction partner in 4–8 hours under ambient conditions; products are obtained in up to 80 per cent yield and 98:2 Z:E diastereoselectivity. The use of this catalyst is demonstrated in the synthesis of the naturally occurring anti-tumour agent neopeltolide and in a single-step stereoselective gram-scale conversion of a renewable feedstock (oleic acid) to an anti-fungal agent. In this conversion, the new catalyst promotes cross-metathesis more efficiently than the commonly used dichloro–ruthenium complexes, indicating that its utility may extend beyond Z-selective processes.

155 citations

Journal ArticleDOI
TL;DR: Carboxylic acid dimers 8a and 9 are more orally efficacious as antimalarials in rodents than either artelinic acid or sodium artesunate, and are strongly inhibitory but not cytotoxic toward several human cancer cell lines.
Abstract: In only two steps and in 70% overall yield, naturally occurring trioxane artemisinin (1) was converted on a gram scale into C-10-carba trioxane dimer 3. This new, very stable dimer was then transformed easily in one additional step into four different dimers 4-7. Alcohol and diol dimers 4 and 5 and ketone dimer 7 are 10 times more antimalarially potent in vitro than artemisinin (1), and alcohol and diol dimers 4 and 5 are strongly growth inhibitory but not cytotoxic toward several human cancer cell lines. Water-soluble carboxylic acid derivatives 8aand 9 were easily prepared in one additional step from dimers 4 and 5. Carboxylic acid dimers 8a and 9 are thermally stable even at 60 degrees C for 24 h, are more orally efficacious as antimalarials in rodents than either artelinic acid or sodium artesunate, and are strongly inhibitory but not cytotoxic toward several human cancer cell lines.

155 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
2023198
2022457
2021459
2020738
2019842
2018813