Sulfonic Acids, Aliphatic

Kosswig, K.

doi:10.1002/14356007.a25_503

Cited by 7 publications

(9 citation statements)

References 10 publications

(9 reference statements)

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“…Again, although innovative, the method cannot be easily generalized to other O -acylations. However, the use of sulfonic acids in acidic O -acylations was instructive [ 29 – 30 ].…”

Section: Reviewmentioning

confidence: 99%

“…Acylation reactions in MeSO 3 H are more vigorous and exothermic than in CF 3 CO 2 H since MeSO 3 H (p K a ≈ −2) is a stronger acid than CF 3 CO 2 H (p K a ≈ 0.5). Their densities are the same (1.48 g/mL at 25 °C), but the melting point of MeSO 3 H (20 °C) is considerably higher than that of CF 3 CO 2 H (−15 °C), and the volatility of MeSO 3 H is insignificant compared to CF 3 CO 2 H, making evaporation of reaction mixtures based on MeSO 3 H entirely unfeasible [ 22 , 29 – 30 ]. Unlike CF 3 CO 2 H, MeSO 3 H has a higher affinity for amines than does HCl, making the crystalline hydrochlorides unavailable from MeSO 3 H medium, thereby complicating the isolation and purification process due to the poor crystallinity of methanesulfonate salts, which in fact, quite frequently are ionic liquids.…”

Section: Reviewmentioning

confidence: 99%

“…An acidic O -acylation of hydroxyproline with acryloyl chloride was possible but somewhat sluggish since this acyl chloride is considerably less reactive than the regular, saturated aliphatic acyl chlorides. The acylating activity of the medium was then fortified by the addition of trifluoromethanesulfonic acid (CF 3 SO 3 H), one of the strongest of all acids known (pK a ≈ −5.5), comparable to, or exceeding perchloric and fluorosulfonic acid (although the ordering of acidities is highly dependent on the solvent medium) [ 29 – 30 50 – 51 ]. First prepared in 1954 [ 52 ], CF 3 SO 3 H (bp.…”

Section: Reviewmentioning

confidence: 99%

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Chemoselective O-acylation of hydroxyamino acids and amino alcohols under acidic reaction conditions: History, scope and applications

Kristensen¹

2015

Beilstein J. Org. Chem.

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SummaryAmino acids, whether natural, semisynthetic or synthetic, are among the most important and useful chiral building blocks available for organic chemical synthesis. In principle, they can function as inexpensive, chiral and densely functionalized starting materials. On the other hand, the use of amino acid starting materials routinely necessitates protective group chemistry, and in reality, large-scale preparations of even the simplest side-chain derivatives of many amino acids often become annoyingly strenuous due to the necessity of employing protecting groups, on one or more of the amino acid functionalities, during the synthetic sequence. However, in the case of hydroxyamino acids such as hydroxyproline, serine, threonine, tyrosine and 3,4-dihydroxyphenylalanine (DOPA), many O-acyl side-chain derivatives are directly accessible via a particularly expedient and scalable method not commonly applied until recently. Direct acylation of unprotected hydroxyamino acids with acyl halides or carboxylic anhydrides under appropriately acidic reaction conditions renders possible chemoselective O-acylation, furnishing the corresponding side-chain esters directly, on multigram-scale, in a single step, and without chromatographic purification. Assuming a certain degree of stability under acidic reaction conditions, the method is also applicable for a number of related compounds, such as various amino alcohols and the thiol-functional amino acid cysteine. While the basic methodology underlying this approach has been known for decades, it has evolved through recent developments connected to amino acid-derived chiral organocatalysts to become a more widely recognized procedure for large-scale preparation of many useful side-chain derivatives of hydroxyamino acids and related compounds. Such derivatives are useful in peptide chemistry and drug development, as amino acid amphiphiles for asymmetric catalysis, and as amino acid acrylic precursors for preparation of catalytically active macromolecular networks in the form of soluble polymers, crosslinked polymer beads or nanoparticulate systems. The objective of the present review is to increase awareness of the existence and convenience of this methodology, assess its competitiveness compared to newer and more elaborate procedures for chemoselective O-acylation reactions, spur its further development, and finally to chronicle the informative, but poorly documented history of its development.

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“…Again, although innovative, the method cannot be easily generalized to other O -acylations. However, the use of sulfonic acids in acidic O -acylations was instructive [ 29 – 30 ].…”

Section: Reviewmentioning

confidence: 99%

Section: Reviewmentioning

confidence: 99%

Section: Reviewmentioning

confidence: 99%

See 1 more Smart Citation

Chemoselective O-acylation of hydroxyamino acids and amino alcohols under acidic reaction conditions: History, scope and applications

Kristensen¹

2015

Beilstein J. Org. Chem.

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“…In an organic follow-up reaction, which also proceeds in the absence of the catalyst, addition of the anhydridic S–O bond of pyrosulfuric acid to ethylene selectively yields ETA. “Free” isethionic acid can subsequently be obtained by hydrolysis under suitable conditions and is the starting material for the industrial synthesis of taurine and numerous surfactants …”

Section: Introductionmentioning

confidence: 77%

Iodine-Catalyzed Selective Functionalization of Ethane in Oleum: Toward a Direct Process for the Production of Ethylene Glycol from Shale Gas

Bilke

Zimmermann

2020

J. Am. Chem. Soc.

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Direct valorization of ethane, a substantial component of shale gas deposits, at mild conditions remains a significant challenge, both from an industrial and an academic point of view. Herein, we report iodine as an efficient and selective catalyst for the functionalization of ethane in oleum at low temperatures and pressures. A thorough study of relevant reaction parameters revealed iodine to be remarkably more active than the previously reported “Periana/Catalytica” catalyst under optimized conditions. As a result of a fundamentally different catalytic cycle, iodine yields the bis-bisulfate ester of ethylene glycol (HO3SO–CH2–CH2–OSO3H, EBS), whereas for state-of-the-art platinum-based catalysts ethionic acid (HO3S-CH2–CH2–OSO3H, ETA) is obtained as the main product. Our findings open up an attractive route for the direct conversion of ethane toward ethylene glycol.

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“… a Experimental p K a data as follows: H 3 PO 4 , 49 HPO(OH) 2 , P(OH) 3 , P(OH) 2 (OEt), HPO(OH)(OEt), P(OH)(OEt) 2 and HPO(OEt) 2, 50 PO(OH)(Et) 2 , 51 PO(OH)( t Bu) 2 , 52 H 2 SO 4 and HSO 3 Me, 53 H 2 SO 3 , 54 HSO 3 F, 55 HSO 3 Et, 56 and HSO 3 CF 3 ,. 57 …”

Section: Resultsmentioning

confidence: 99%

Sulfur and Phosphorus Oxyacid Radicals

et al. 2022

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We report a computational study of the little-studied neutral bisulfite, bisulfate, dihydro-phosphite, and dihydro-phosphate radicals (HSO x • , H 2 PO x • , x = 3,4), calling special attention to their various tautomeric structures together with p K a values estimated from the Gibbs free energies of their dissociations (at the G4 and CAM-B3LYP levels of density functional theory). The energetics of microhydration clusters with up to four water molecules for the S-based species and up to eight water molecules for the P-based species were investigated. The number of microhydrating water molecules needed to induce spontaneous de-protonation is found to correlate the acid strength of each radical. According to the computed Gibbs free reaction and activation energies, S- and P-centered radicals preferentially add to the double bond of propene (a lipid model), whereas the O-centered radical tautomers prefer H-abstraction. The likely downstream reactions of these radicals in biological media are discussed.

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Sulfonic Acids, Aliphatic

Cited by 7 publications

References 10 publications

Chemoselective O-acylation of hydroxyamino acids and amino alcohols under acidic reaction conditions: History, scope and applications

Chemoselective O-acylation of hydroxyamino acids and amino alcohols under acidic reaction conditions: History, scope and applications

Iodine-Catalyzed Selective Functionalization of Ethane in Oleum: Toward a Direct Process for the Production of Ethylene Glycol from Shale Gas

Sulfur and Phosphorus Oxyacid Radicals

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