Organic Acids without a Carboxylic Acid Functional Group

Perez, G. V.; Pérez, Alice L.

doi:10.1021/ed077p910

Cited by 55 publications

(36 citation statements)

References 31 publications

(31 reference statements)

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“…Deltic acid, with a three-membered ring, was first synthesized by Eggerding et al in 1975 [56]. Although deltic acid possesses low diacid dissociation constants (pKa 1 = 2.6 and pKa 2 = 6.0) [57], similarly to squaric acid, the acid is difficult to use as an anodizing electrolyte because it easily decomposes in aqueous and ethanol solutions [56]. Croconic acid, with a five-membered ring, and rhodizonic acid, with a six-membered ring, are long-known chemical species whose detailed chemical structures were only recently determined.…”

Section: Introductionmentioning

confidence: 99%

“…Croconic acid, with a five-membered ring, and rhodizonic acid, with a six-membered ring, are long-known chemical species whose detailed chemical structures were only recently determined. Croconic acid possesses low pKa values of 0.8 and 2.2 [57,58], and similarly, rhodizonic acid possesses low pKa values of 4.3 and 4.7 [57,59,60]. Heptagonic acid, with a seven-membered ring, is not commercially available at the present time, although the possibility of synthesizing heptagonic acid was reported by Seits et al [61] Based on the considerations outlined above, it is strongly believed that croconic and rhodizonic acid have the potential to behave as suitable electrolytes for the fabrication of anodic porous alumina.…”

Section: Introductionmentioning

confidence: 99%

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Fabrication of anodic porous alumina via anodizing in cyclic oxocarbon acids

Kikuchi

Nakajima

Kawashima

et al. 2014

Applied Surface Science

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The growth behavior of anodic porous alumina formed by anodizing in novel electrolyte solutions, the cyclic oxocarbon acids croconic and rhodizonic acid, was investigated for the first time. High-purity aluminum specimens were anodized in 0.1 M croconic and rhodizonic acid solutions at various constant current densities. An anodic porous alumina film with a cell size of 200-450 nm grew uniformly on an aluminum substrate by rhodizonic acid anodizing at 5-40 Am -2 , and a black, burned oxide was formed at higher current density. The cell size of the porous alumina increased with current density and corresponding anodizing voltage. Anodizing in croconic acid at 293 K caused the formation of thin anodic porous alumina films as well as black, thick burned oxides. The uniformity of the porous alumina improved by increasing the temperature of the croconic acid solution, and anodic porous alumina films with a uniform film thickness were successfully obtained. Our experimental results showed that the cyclic oxocarbon acids croconic and rhodizonic acid could be employed as a suitable electrolyte for the formation of anodic porous alumina films.Key words: Aluminum; Anodizing; Anodic Porous Alumina; Croconic Acid; Rhodizonic Acid IntroductionThe anodizing of aluminum in several different acidic solutions causes the formation of anodic porous alumina (i.e., porous anodic oxide film) with characteristic nanofeatures on aluminum substrates. Porous alumina consists of nano-scale hexagonal cells perpendicular to the substrate, and each cell possesses a nanopore at its center [1,2]. These cells are self-ordered by anodizing under appropriate electrochemical conditions, especially under a high electric field [3,4]. When anodic porous alumina is immersed in boiling distilled water after anodizing, the nanopores are filled by hydroxide (pore-sealing) [5,6]. The sealing process causes the formation of a highly crystalline hydroxide layer on the surface of the anodic oxide, and the hydroxide layer is highly dissolution-resistant in acidic and alkaline solutions. Using these characteristic structural and chemical properties, anodic porous alumina has been widely investigated for many applications: antireflection structures [7,8] [50] acid have been reported to date for the fabrication of anodic porous alumina. Oxalic and malonic acid anodizing have been reported to give rise to self-ordering behavior under suitable anodizing conditions. The organic and inorganic electrolytes used to fabricate anodic porous alumina possess low dissociation constant (pKa) in aqueous solution, except for glycolic and formic acid, are diacids or triacids. However, glycolic and formic acid form dimers via hydrogen bonding in aqueous solution and may behave like diacids [52,53]. The nanofeatures of anodic porous alumina, including cell size (i.e., interpore distance) and pore diameter, are limited by these electrolytes during anodizing. Therefore, the discovery of additional electrolytes is very important in expanding the applicability of porous alum...

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Fabrication of anodic porous alumina via anodizing in cyclic oxocarbon acids

Kikuchi

Nakajima

Kawashima

et al. 2014

Applied Surface Science

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“…26 These differences have been explained by dipole minimization arguments for each conjugate base as well as ground state energy differences of the starting compounds. 27 While this may also apply to our results, the propensity of compounds 8-13 toward elimination and failure of 22 might be best explained by considering the aromatic nature, and thus increased stability and ease of formation, of the conjugate base for each cyclic compound. 22 Efforts are ongoing to validate this rationalization to better inform these and other sulfone elimination reactions currently under investigation.…”

Section: Scheme 6 Substituted γ-Alkylidene Butenolide Synthesismentioning

confidence: 56%

Ring-Closing Metathesis Reactions of Acyloxysulfones: Synthesis of γ-Alkylidene Butenolides

Phan

Gilbert

O’Neil

2015

Synlett

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“…This results in high acidity (pKa1 = 1.2-1.7, pKa2 = 3.2-3.5). The accepted acidity constants of squaric acid are pKa1 = 0.54 and pKa2 = 3.48 [71] and intrinsic properties of an organic acid [72] compared with sulphuric acid (pKa1 = -3.0 and pKa2 = 1.92) as shown in Figure 6. This inherent property of squaric acid makes it more anionic than other enols such as phenol (pKa ~10) or cyclopentane-1,3-diones (pKa ~6) at physiological pH.…”

Section: Squaric Acidmentioning

confidence: 99%

Squaryl Molecular Metaphors – Application to Rational Drug Design and Imaging Agents

Kitson¹

2017

J Diagn Imaging Ther

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Molecular Metaphors is the application of squaryl building blocks towards creative functional group chemistry to produce lead compounds and imaging agents. This strategy is applied to rational drug design and to various imaging agents that would normally contain conventional functional group chemistry. These, include carboxylic acids, α-amino acids, peptide bonds and phosphonates. Moreover, the squaryl metaphor is a precursor to complex organic molecules involving functional group interchange (FGI) and rearrangements. This article discusses the application of these metaphors in the area of neurochemistry, especially NMDA receptors. An important area of drug design is the inhibition of angiotensin II enzyme by the use of losartan. This commercial drug contains a tetrazole moiety that can be modified using the squaryl group to give a semisquarate derivative. These concepts can extend to the semisquarate of ibuprofen. Moreover, a discussion on peptidomimetics regarding the substitution of the peptide bond for squaramide allows for a change in the biological properties due to modification at the peptide bond. Furthermore, the topic on how squaryl metaphors can be exploited primarily by the central 1,3-hydroxyamide sequence to the generation of a novel class of HIV protease inhibitors. Also, squaryl metaphors can be used to develop potential inhibitors of glutathione and novel anti-migraine drugs. The discussion continues on the design of anticancer drugs: in particular, a novel class of metalloproteases, including phosphonates for semisquaramides, leading to squaryl nucleosides. This review concludes with the application of squaryl metaphors in the design of positron emission tomography (PET) and magnetic resonance imaging (MRI) agents towards theranostics. describe the ability of individual functional chemical groups to mimic other moieties [2,3]. KeywordsErlenmeyer rationalised these concepts and categorised isosteres into atoms, ions and molecules based on the valence level of electrons [4]. A further understanding by Friedman led to the term bioisosterism to include all atoms and molecules that fit the broadest definition of isosteres [5]. This approach was independent of whether the drug was an agonist or an antagonist towards biological activity.Moreover, Thornber applied the term bioisosterism to include subunits, groups or molecules that possess physicochemical properties of similar biological effects [6]. Finally, in 1991 Burger widened the definition of bioisosteres to include compounds or groups that possess similar molecular shapes and volumes independent of agonists or antagonists [7]. REVIEW ARTICLE Squaryl KitsonThese bioisosteres would require approximately the same distribution of electrons and give a high probability of generating comparable physical properties such as hydrophobicity [8]. Currently, bioisosterism is one of the most useful tools to the medicinal chemist in rational drug design and in particular regarding the carboxylic acid bioisosteres [9]. The carboxylic acid functional ...

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Organic Acids without a Carboxylic Acid Functional Group

Cited by 55 publications

References 31 publications

Fabrication of anodic porous alumina via anodizing in cyclic oxocarbon acids

Fabrication of anodic porous alumina via anodizing in cyclic oxocarbon acids

Ring-Closing Metathesis Reactions of Acyloxysulfones: Synthesis of γ-Alkylidene Butenolides

Squaryl Molecular Metaphors – Application to Rational Drug Design and Imaging Agents

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