Aryl Acetates Research Articles

Infrared spectroscopy-based property-reactivity correlations for predicting environmental fate of organic chemicals

A conventional structure-activity relationship (SAR) has been established between the alkaline hydrolysis rate constants (koh) of 12 alkyl and aryl formates and acetates and the linear combination of the frequencies of the C=o and C—o infrared (IR) absorbance peaks. The inability of this relationship to predict koh values for more structurally diverse carboxylic acid esters led to the development of a prototype of a prediction system that employs multiple linear regression analysis, using points from the Fourier transforms (FTs) of IR spectra. Conventional SARs have also been observed between single IR peak parameters and the microbial degradation rate constants of amides (C=O peak frequencies), 2,4-dichlorophenoxyacetate esters (CH peak intensities), phenols (OH peak frequencies), and anilines (NH stretching peak intensities). These observations indicate the feasibility of extending the FT-based prediction system to microbial degradation when reliable rates are available for additional compounds.

Differential metal ion stabilization of reactants and transition states in the transacylation of crown ether aryl acetates

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTDifferential metal ion stabilization of reactants and transition states in the transacylation of crown ether aryl acetatesRoberta Cacciapaglia, Arie R. Van Doorn, Luigi Mandolini, David N. Reinhoudt, and Willem VerboomCite this: J. Am. Chem. Soc. 1992, 114, 7, 2611–2617Publication Date (Print):March 1, 1992Publication History Published online1 May 2002Published inissue 1 March 1992https://doi.org/10.1021/ja00033a038RIGHTS & PERMISSIONSArticle Views135Altmetric-Citations25LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (847 KB) Get e-AlertsSupporting Info (1)»Supporting Information Supporting Information Get e-Alerts

Threo‐3‐Alkyl‐ and ‐Arylglutamic Acid Derivatives by Michael Additions of Boc‐BMI Li‐Enolates to 2,6‐Di‐t‐butyl‐4‐methoxyphenyl Alkenoates on the Diastereoselectivity of the Coupling of Trigonal Centers Involving Heterocyclic Li‐Enolates

AbstractThe conjugated esters 5, 6, 8, 9 mentioned in the title are prepared from the corresponding aryl acetate 4 and aldehydes by aldol condensation (direct enoylation of the hindered phenol with the corresponding unsaturated acid chlorides gave only poor yields). To avoid double‐bond shifts, the 4‐phenyl 2‐butenoate 7a was prepared from the saturated one by selenation/elimination (see 7b, c in Scheme 1). In contrast to methyl and ethyl crotonates, reacting in poor yields and with low selectivities (→11, 12), the hindered aryl enoates combine with the Li‐enolate of 1 [(S)‐Boc‐BMI, a chiral glycine derivative] to give single products 13a–17a (⩾95% ds) in high yields (78–96% of purified samples, Scheme 2). The configuration of the two newly formed stereogenic centers and thus the mode of coupling of the trigonal centers in the Michael addition (D and E in Scheme 4) is derived for the methyl (13a) and benzyl substituted (15a) derivatives by multiple chemical correlation (see 19–24 in Scheme 3). It is shown that pure (2S,3R)‐glutamic acids 22, 23 can be isolated by hydrolysis of the adducts 13a, 15a of conjugate addition. — The results of the aldol, Michael and nitro olefin additions of heterocyclic Li‐enolates are collected and compared (Scheme 5, Table 1). Possible reasons for the high diastereoselectivity and a typical coupling mode of most reactions involving N‐acylimidazolidinone and N‐acyloxazolidinone Li‐enolates M, O are discussed (see W in Scheme 6).

Flow-injection analysis with tetrameric calixarene-based potentiometric detection

The performance of potentiometric detection based on calix[4]arene compounds was investigated for use in flow injection analysis. Two neutral carriers, namely methyl p-tert-butylcalix[4]aryl acetate and the methyl tetraketone derivative of p-tert-butylcalix[4]arene, showed excellent stability and rapid response to sodium in a series of carrier streams. The application of these membrane electrodes to the determination of sodium in clinical samples was assessed and compared with flame photometry and a hospital-based autoanalyser. The results obtained suggest that the flow-injection approach offers a significant improvement in precision and accuracy in comparison with a dip method reported earlier.

Diastereofacial selectivity with optically active .alpha.-substituted .beta.-silyl-(E)-hexenoates. Enantioselective construction of homoallylic ethers via reaction with aryl acetals

Diastereofacial selectivity with optically active .alpha.-substituted .beta.-silyl-(E)-hexenoates. Enantioselective construction of homoallylic ethers via reaction with aryl acetals

Structural requirements for glyme catalysis in butylaminolysis of aryl acetates in chlorobenzene. Identification of -OCH2CH2OCH2CH2OCH2CH2O- as the optimal subunit for catalysis

Evidence is presented using a Hammet study that four oxygens in a ―OCH 2 CH 2 OCH 2 CH 2 OCH 2 CH 2 O― subunit are necessary for optimal catalysis. The Hammett study supports the conclusions of others that breakdown of the zwitterionic tetrahedral intermediate is rate-limiting. The result imply a specific structure for a glyme-zwitterionic tetrahedral intermediate complex, which contains an ammonium ion that hydrogen bonds to the ether oxygens

1H NMR Spin‐echo Spectroscopy of Human Erythrocytes. Transformation of Exogenous Compounds

1H NMR spin-echo spectroscopy has been used to study the metabolism of exogenous compounds in human erythrocytes. The non-invasive nature of the technique and the continuous monitoring makes it ideal to investigate both the conversion of substrates and the occurrence and the nature of the products. Hydrolysis rates may be determined and the hydrolysis of alkyl, vinyl, and aryl acetates are shown to be due to A-esterase activity. The conversion products are normally observed, but in the case of dimethyl phthalate and methyl acetate only part of the methanol is found. An interesting case is the hydrolysis of vinyl acetate and the consecutive conversion of the vinyl alcohol to acetaldehyde (hydrate). Coupling of glutathione to a variety of vinyl derivatives is also observed. Oxidation of acetaldehyde can also be followed. Styrene and 5-chloro-2-methylaniline are slowly converted in what is believed to be oxidation reactions. Changes in 1H chemical shifts are observed for a number of compounds upon uptake into human erythrocytes, a shift that is suggested to be due to binding to haemoglobin.

The rhodium-catalysed methanolysis of aryl acetates and of the hexafluorophosphate anion

In nitromethane, the methanolysis of aryl acetates is catalysed by the tetrafluoroborate and hexafluorophosphate salts of the (η5-ethyltetramethylcyclopentadienyl) (η6-benzen)rhodium(III) cation. Under the conditions of the methanolysis, the anion of the latter salt reacts with methanol to give dimethyl phosphorofluoridate. The hydrogen fluoride formed also in this reaction is thought to be responsible for the greater efficiency of the hexafluorophosphate salt as a catalyst for the methanolysis.

ChemInform Abstract: A Facile and Direct Conversion of Aryl Acetate to Alkyl Aryl Ether.

AbstractIn order to prepare naturally occurring furochromones, the acetoxybenzofurans (I) and (IV) are treated with excess methyl iodide (II) and sodium hydride in the presence of HMPA to yield directly the methoxy analogues (III) and (V) as the main products.

Comparison of a calixarene-based ion-selective electrode with two automated analyzers for the clinical determination of sodium in blood plasma

Neutral-carrier ion-selective electrodes based on methyl p-t-butylcalix[4]aryl acetate have been prepared that are responsive to sodium ions. The miniaturized catheter-type electrodes were obtained by dip-coating their porcelain tips in a PVC membrane cocktail. Examination of the general performance of the electrodes revealed excellent characteristics in terms of Nernstian response, selectivity, stability, reproducibility and response time. The results from the indirect potentiometric assessment of a large number of plasma samples with the electrodes showed a good correlation with the results from two automated analyzers (Technicon Smac 3, Hitachi 704) and with flame photometric data. Although inconsistencies were observed in the measurement of some plasma samples, the variance seemed to be method-dependent, and the overall performance of the electrodes showed promise as an alternative to the sodium glass electrode. Some factors influencing the standard potential of the measuring cell are discussed as a source of error.

A Selective Hydrolysis of Aryl Acetates

A Selective Hydrolysis of Aryl Acetates

ChemInform Abstract: Novel Acylating Agents from Aryl(dimethylbenzylammonium) Acetates.

AbstractThe title compounds (I) are found to be versatile acylating agents.

Synthèses et caractérisation d'une nouvelle classe de sels de flavylium; voie d'accès aux composés du type (acétoxy‐2‐phényl)2‐méthylidène‐4‐4H‐benzopyranne‐1. Structure radiocristallographique de l'(acétoxy‐2‐méthyl‐5‐phényl)‐2‐diméthyl‐4, 6‐benzopyranne‐1‐ylium pentachlorostannate: mise en évidence de ponts chlore dans l'uniteé decachlorodistannate(2–)

Synthesis and Characterization of a New Class of Flavylium Salts; a Facile Route to the 2‐(2‐Acetoxyphenyl)‐4‐methylidene‐4H‐1‐benzopyran Derivatives. X‐Ray Crystal Structure of 2‐(2‐Acetoxy‐5‐methylphenyl)‐4,6‐dimethyl‐1‐benzopyranylium Pentachlorostannate: Supporting evidence of Chlorine Bridging in the Decachlorodistannate(2–) UnitSeveral mixtures of compounds 1 and 2 were synthesized from SnCl4 and p‐substituted aryl acetates. Separation of 1/2 was achieved either by treatment of the mixture with MeCN providing the pure complex 1 or by reaction with MeCOCl leading selectively to a new class of flavylium salts 3 or 4. The structure of 2‐(2‐acetoxy‐5‐methylphenyl)‐4,6‐dimethyl‐l‐benzopyranylium pentachlorostannate (3a) was determined by single‐crystal X‐ray diffraction. The Sn‐atoms are hexacoordinated in the dimeric unit Sn2Cl through Cl bridging. Furthermore, we report the easy preparation of 1‐benzopyran derivatives starting from the salts 3.

Selective oxidation of hydrocarbons via CH bond activation by soluble and supported palladium catalysts

Aldehydes, ketones and vinylic oxidation products such as acetaldehyde, acetone and vinyl acetate are manufactured by related heterogeneous and homogeneous catalytic reactions involving nucleophilic attack on Pd(II)olefin π-complexes. Carbonhydrogen bond activation (β-hydrogen elimination) always occurs after nucleophilic attack in these cases. Another family of industrially important products: α,β-unsaturated alcohols, esters and acids such as acrylic acid, allyl acetate and methacrylic acid can be produced by reactions involving nucleophilic attack on a palladium-olefin π-allyl complex. In these cases CH bond activation precedes nucleophilic attack. The oxidation state of the metal is a critical factor in determining when CH bond activation will occur and therefore which direction these reactions will take. Liquid phase palladium catalyzed oxidation of aromatic substrates via aromatic CH bond activation gives either phenols and aryl acetates or products of oxidative dimerization. Oxidative coupling is favored by lower oxidation state catalysts whereas ring oxidation is favored by high oxidation state systems. Alkyl aromatic compounds undergo oxidation at the alkyl side chain. Benzylic oxidation is favored by low oxidation state palladium whereas more electrophilic high oxidation state species attack the ring.

17O NMR studies on substituted N‐arylacetamides and aryl acetates: Torsion angle and electronic effects

Abstract17O NMR spectroscopic data at natural abundance in acetonitrile at 75°C were obtained for sixteen N‐arylacetamides, three N‐methyl‐N‐arylacetamides and seven aryl acetates. The 17O chemical shifts of the N‐arylacetamides are significantly influenced by both electronic and steric factors. A Hammett plot of the data for 4‐substituted N‐arylacetamides gives a slope of 22 ppm. Ortho substituents result in significant shielding effects, in contrast to previously reported results for conjugated ketnoes. A quantitative relationship between 17O chemical shift data and torsion angle was found for the sterically hindered arylacetamides. Electronic effects on the aryl acetate 17O chemical shifts are, in comparison, greatly reduced. Steric factors for aryl acetates show even smaller effects on the 17O chemical shifts.

A sodium ion-selective electrodebased on methyl p-t-butylcalix[4]aryl acetate as the ionophore

The performance of sodium-selective electrode based on the ligand methyl p-t-butylcalix[4]aryl acetate, one of a new series of ionophores, is described. The selectivity pattern with respect to clinically common cations is better than those of some currently available sodium-selective ionophores. Near-Nernstian response is obtained in the range 10 −1−10 −4 M. Response times are typically around 3 s and membrane resistances are of the order of 10 6Ω.

Catalytic recruitment in the inactivation of acetylcholinesterase by Soman: temperature dependence of the solvent isotope effect

3,3-Dimethyl-2-butyl methylphosphonofluoridate (soman) recruits at least 60-70% of the catalytic power of acetylcholinesterase during phosphonylation of the active-site serine, as compared with the acetylation by acetylcholine. The solvent isotope effect is 1.34 +/- 0.11 and is temperature independent within experimental error between 5 and 45/sup 0/C. This observation is quite similar to what has been found for the reactions of aryl acetates and anilides. Average activation parameters for the same temperature range are ..delta..H* = 7.3 +/- 0.6 kcal/mol and ..delta..S* = -4 +/- 2 eu (H/sub 2/O) and ..delta..H* = 7.1 +/- 0.4 kcal/mol and ..delta..S* = -6 +/- 1 eu (D/sub 2/O). A rate-limiting process with 50% contribution of an induced-fit conformational change is supported by the data.

Hydration of acylimidazoles: tetrahedral intermediates in acylimidazole hydrolysis and nucleophilic attack by imidazole on esters. The question of concerted mechanisms for acyl transfers

Heats of hydrolysis have been measured for three acylimidazole acetals. From these results free energies of formation in aqueous solution have been calculated for the acetals and the corresponding tetrahedral intermediates. Having free energies of formation for the tetrahedral intermediates allows a detailed analysis of the energetics of both the unobservable nucleophilic reaction of imidazole with ethyl acetate and also the observable reaction of imidazole with p-nitrophenyl acetate. pKa values of 1-(3-aminopropyl)-imidazole and 1-(2-aminoethyl)-imidazole have been determined to allow calculation of the σ* value for the imidazolyl substituent. The dependence of imidazole pKa values on the electron-withdrawing properties of the 1-substituent was also determined. There is a linear free energy relation between the free energy change for replacement of OH in a carbonyl hydrate by imidazolyl and the sum of the σ* values for the other substituents. The implications of these results for the question of concerted versus stepwise mechanisms for the reactions of imidazole with aryl acetates have been examined. An equilibrium constant has been calculated for the addition of imidazole to p-nitrophenyl acetate. A simple extension of Marcus theory allows the free energy surface for a three-dimensional reaction coordinate diagram to be calculated using the energy levels of the tetrahedral intermediate determined in this work, the energy level of the acylium ion derived from literature data, and intrinsic barriers for the edge reactions. It is shown that the reaction of imidazole with p-nitrophenyl acetate probably follows a concerted path. General conclusions from this theory of concerted reactions are discussed.

Silicon–oxygen and acyl–oxygen bond cleavage in reactions of sterically hindered organosilicon carboxylates

Because of steric hindrance to attack at the functional silicon centre in VsiSiMe2OCOR [where Vsi denotes (Me3Si)2(CH2CHMe2Si)C] with R = CF3(1a) or Me (1b), nucleophiles in MeOH can preferentially attack at the carbonyl group to give VsiSiMe2OH, rather than at Si as would be usual for less hindered silicon carboxylates. With CsF or KSCN in MeOH the products are exclusively VsiSiMe2F and VsiSiMe2NCS, respectively, whereas KOCN gives exclusively VsiSiMe2OH, and NaN3 gives very predominantly VsiSiMe2OH along with a little VsiSiMe2N3. The overall effectiveness of the salts is KOCN > CsF, NaN3 > KSCN; the sequence of the case of attack of the nucleophiles at Si is F– > SCN–(>N3–?), and that for attack at carbon is OCN– > N3– > F– > SCN–. The sequence of ability of various nucleophiles to catalyse cleavage of the SiO–COR bond of (1a) in MeOH is RNH2(R = H2N, Me, Et, HOCH2CH2, or H2NCH2CH2), OCN–, HO2– > MeO– > N3– > Me2NH > Me3N > 4-Me2NC5H4N C5H5N > PhNH2, and the sequence for reactions of the less reactive (1b) is HO2– > H2NNH2 > MeO– > H2NCH2CH2NH2 > MeNH2 > HOCH2CH2NH2 > EtNH2. Except for the unexpected effectiveness of OCN–, the sequences are reasonably consistent with those established, for example, for reactions of aryl acetates in water (and also with Ritchie's nucleophilic parameters N+); it is suggested that, as in the latter reactions, the cleavage of the acyl–oxygen bond is rate-determining. Reactions of (1a) with salts MX, namely NaN3, CsF, KSCN, and KOCN in MeCN, give exclusively the corresponding species VsiSiMe2X. In the representative reactions examined the reactivities of (1a) and (1b) were very similar to those of the corresponding compounds (Me3Si)3CSiMe2OCOR.

Nonlinear structure–reactivity correlations. The hydrolysis of 2,4,6‐trinitrophenyl acetate catalyzed by general bases

AbstractThe hydrolysis of 2,4,6‐trinitrophenyl acetate was studied in the presence of several carboxylic bases and tertiary amines. Carboxylic bases pyridine and imidazole react as nucleophilic catalysts, while 2,4‐dimethyl and 2,4,6‐trimethyl pyridine react as general‐base catalysts. The nonlinear structure–reactivity correlations (log kcat versus log kOH and log kcat versus pK of the leaving group) for the series of aryl acetates are discussed, and it is suggested that there is a change in transition‐state structure along the series.