Alkyl Acetates Research Articles

Measurements and Analysis of Excess Enthalpies of Alkyl Acetates + 1‐Chloroalkanes Using the Unifac Model

AbstractMolar excess enthalpies at 298.15 K and atmospheric pressure are reported for eight binary liquid mixtures of alkyl (methyl and propyl) acetates + 1‐chloroalkanes (pentane, hexane, heptane and octane). The experimental results along with literature data of ethyl acetate with the same 1‐chloroalkanes are examined by a version of the UNIFAC model. In general, the model reproduces the experimental data within the limits of error. The maximum discrepances are observed in those mixtures where the acetate with the largest alkyl radical intervenes; however, the average overall error of the twelve systems analysed here is less than 6.5 per cent.

Ion–dipole complexes in the unimolecular reactions of isolated organic ions. Fragmentation of protonated and cationated formate and acetate esters

The unimolecular fragmentation reactions occurring on the metastable ion time scale have been determined for protonated alkyl formates and acetates and for the adducts of CD3+ and C2H5+ with these esters. The protonated esters, R1CO2RH+, fragment to form R+ + R1CO2H or, by internal hydrogen transfer, R1CO2H2+ + (R – H) with the relative yields depending on the identity of R1 and R. Using deuterium labelling it has been shown that the added proton interchanges with hydrogens of the R group prior to fragmentation. The methyl-d3-cationated esters, R1CO2R•CD3+, mostly fragment to give R1CO2CD3, H+ by elimination of (R – H), although R+ formation is observed in a few cases. The ethyl-cationated esters fragment primarily to give R1CO2C2H5•H+ by elimination of (R–H); specifically no elimination of C2H4 is observed. All of the results can be rationalized in terms of a step-wise mechanism of fragmentation involving initial formation of an ion–dipole complex of the alkyl ion R+ with a carbonyl compound. This complex may either fragment to form R+ or may proceed by way of an ion–dipole complex of a protonated carbonyl and an olefin to the protonated species plus (R – H). The results indicate that primary alkyl ions are not formed but rather that rearrangement to the more stable secondary or tertiary structure occurs. There is some evidence that s-butyl cations are not formed, but that these too rearrange to the t-butyl structure.

A Simple and Efficient Synthesis of Alkyl (2-Nitroaryl)acetates and Alkyl 2-(2-Nitroaryl)propanoates via Vicarious Nucleophilic Substitution of Hydrogen in Nitroarenes by Carbanions or Alkyl Chloroacetates of Alkyl 2-Chloropropanoates

A Simple and Efficient Synthesis of Alkyl (2-Nitroaryl)acetates and Alkyl 2-(2-Nitroaryl)propanoates via Vicarious Nucleophilic Substitution of Hydrogen in Nitroarenes by Carbanions or Alkyl Chloroacetates of Alkyl 2-Chloropropanoates

ChemInform Abstract: Cobalt Carbonyl Catalyzed Reactions of Esters and Lactones with Hydrosilane and Carbon Monoxide. A Novel Synthetic Method for the Introduction of the Siloxymethylidene Group.

AbstractA new methodology for making C‐Co bonds by utilizing the high affinity of Si in R3SiCo(CO)4 for oxygen, has resulted in the development of new catalytic reactions of alkyl acetates and lactones with hydrosilanes R3SiH and CO in the presence of Co2(CO)8.

Cobalt carbonyl catalyzed reactions of esters and lactones with hydrosilane and carbon monoxide. A novel synthetic method for the introduction of the siloxymethylidene group

The catalytic reactions of esters and lactones with hydrosilane and carbon monoxide in the presence of Co/sub 2/(CO)/sub 8/ have been studied in detail with the emphasis being focused on their utility in organic synthesis. The catalytic reaction of secondary alkyl acetates underwent clean incorporation of carbon monoxide to give (siloxymethylidene)alkanes (enol silyl ethers). Lactones of secondary alkyl ester type reacted similarly. The siloxymethylidenation products were converted to aldehydes. Primary alkyl acetates gave several products in a nonselective manner. In the case of tertiary alkyl esters, no incorporation of carbon monoxide took place except for bridgehead alkyl acetates. The mechanism of the catalytic reaction has been proposed, and the importance of the silycobalt carbonyl, R/sub 3/SiCO(CO)/sub 4/, as the key catalyst species has been suggested. The high affinity of the silicon in R/sub 3/SiCo(CO)/sub 4/ toward the oxygen atom in the ester is suggested to be the driving force for the formation of alkylcobalt carbonyls as the intermediates. This step illustrates a new methodology for the formation of a carbon-transition metal bond.

Quinazolines and 1,4‐benzodiazepines. XCV. Synthesis of 1,4‐benzodiazepines by ring expansion of 2‐chloromethylquinazolines with carbanions

Abstract1,4‐Benzodiazepines bearing a carbon substituent at the 2‐position were obtained by reaction of 2‐chloromethylquinazoline 3‐oxides with stabilized carbanions. The carbanions of alkyl acetates, N,N‐disubstituted acetamides, acetonitrile, dimethylsulfone, N,N‐dimethyl methanesulfonamide and 2‐methylpyridine were successfully applied. The conversion of some of the 2‐carbon substituted 1,4‐benzodiazepines to imidazo[1,5‐a][1,4]benzodiazepines and [1,2,5]oxadiazino[5,4‐a][1,4]benzodiazepines is described.

Preparation of Pheromones by Simple Procedures

(Z)-9-Tetradecenyl methanesulfonate derived from (Z)-9-tetradecenoic acid (myristoleic acid) of beef tallow served as starting material for the preparation of sets of alcohols, alkyl acetates, and aldehydes having 16 and 18 carbon atoms. These com pounds are known to function as pheromones in various insect species. Chain elongation of (Z)-9-tetradecenyl methanesulfonate by malonic ester synthesis follow ed by esterification afforded the methyl ester of (Z )-11-hexadecenoic acid. This ester was converted to a set of pherom ones having a C16-chain with a (Z)-double bond in position 11. Chain elongation of (Z )-11-hexadecenyl methanesulfonate yielded the m ethyl ester of (Z)-13-octadecenoic acid which was used for the preparation of a set of pheromones having a C18-chain with a (Z)-double bond in position 13. All the reaction steps involved provided excellent yields.

Dehydrohalogenation Reactions Using Hindered Lithium Dialkylamide Bases

Abstract The E2 eliminations of 2-substituted butanes with a series of hindered lithium dialkylamide bases has been exmined. Excellent yields of butenes are obtained using 2-bromobutane and 2-iodobutane. Alkyl chlorides, acetates and tosylates give poor yields of olefin product. Elimination reactions show a rise, then a fall, in the 1-butene/2-butene(s) product ratio as the amide bulk increases. Dehydrohalogenation of 2-bromobutane with lithium 2,2,6,6-tetramethylpiperidide in the presence of one equivalent of 12-crown-4 gives 1-butene/2-butene(s) product ratio of 99:1.

Activity of ruthenium/iodine catalysts for the carbonylation of esters to give carboxylic acids

Abstract Homogeneous ruthenium/iodide systems under a pressure of carbon monoxide effectively catalyze the isomerization of methyl formate to acetic acid with yields in the range of 70%. If alkyl acetates are treated with CO/H 2 , the dominant process is the carbonylation of the alkoxy moiety rather than the homologation of the acetyl or alkoxy moieties; e.g. n-butyl acetate is converted mainly into valeric acid and its derivatives, along with acetic acid and butane. Only in the case of methyl acetate is homologation of the alkoxy moiety, to give ethyl acetate along with acetic acid, the major process. This duality of behaviour can be rationalized in terms of η 2 -acetyl intermediates, which can be hydrogenated to ethanol rather than hydrolyzed to acetic acid. Ester carbonylation is shown to be fast compared with alcohol carbonylation or acid homologation; esters are probably intermediates in the last process.

Transesterification of Alkyl Acetates in Head Space Sampler

Abstract Environmental exposure of workers to organic solvents are routinely evaluated. Field samples are adsorbed on charcoal tubes and analysed by conventional GC or headspace (HS) GC. In the validation process of analytical protocols by HS-GC, it was observed that analysis of alkyl acetates yielded non-reproducible results when benzyl alcohol was used as desorbing solvent. Further studies by HS-GC with capillary column and GC-MS demonstrated a transesterification process of alkyl acetates. Reaction rate is dependent on steric hindrance of the acetate and on volatility of the newly formed alcohol. The presentation will describe some ways to obtain accurate and reproducible results. Data on environmental exposures of workers has been cumulated over two years in various industries involved in painting operations. Average worker exposure to aliphatic acetates will be discussed as well as other organic contaminants.

Effects of Solute-Solvent Interactions in Liquid Adsorption Chro- Matography with Mixed Mobile Phase

Abstract Two simple equations, involving formation of the multimolecular solvates in the mobile phase, are discussed. These equations define the dependence of the capacity ratio upon mobile phase composition. The LC data, available from the literature, for different alcohols chromatographed in binary mixtures of n-heptane with alkyl acetate and tetrahydrofuran on Partisil 10 at 298 K are used to examine these equations.

ChemInform Abstract: SYNTHESIS OF 8‐METHOXY‐ AND 8‐METHOXY‐6‐METHYLHOMOPHTHALIC ANHYDRIDES, KEY INTERMEDIATES FOR THE SYNTHESIS OF ANTHRACYCLINONES AND PERI‐HYDROXYLATED POLYCYCLIC AROMATIC COMPOUNDS

AbstractAus dem Oxocyclohexenyldicarbonsäuredimethylester (I) wird durch Oxidation mit DDQ oder mit Schwefelblume der 3‐Hydroxyhomo‐ phthalsäureester (II) gewonnen; dieser wird O‐methyliert und nach alkalischer Hydrolyse zum Homophthalsäureanhydrid (IV) cyclisiert.

Synthesis, X-ray crystal structures, and cation transfer properties of alkyl calixaryl acetates, a new series of molecular receptors

Calix[4]-, [6]-, and [8]-arenes have been converted into a series of alkyl acetates which show significant phase-transfer activity and selectivity towards alkali metal picrates; the X-ray crystal structure of two members of the series, (1b) and (2d), have been determined.

Gas-phase elimination kinetics of (dimethylamino)alkyl acetates. The ion-pair mechanism through neighboring group participation

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTGas-phase elimination kinetics of (dimethylamino)alkyl acetates. The ion-pair mechanism through neighboring group participationGabriel Chuchani, Alexandra Rotinov, Rosa M. Dominguez, and Neil GonzalezCite this: J. Org. Chem. 1984, 49, 22, 4157–4160Publication Date (Print):November 1, 1984Publication History Published online1 May 2002Published inissue 1 November 1984https://doi.org/10.1021/jo00196a011RIGHTS & PERMISSIONSArticle Views115Altmetric-Citations8LEARN 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 (454 KB) Get e-Alerts Get e-Alerts

Photoinduced reactions of organic compounds with transition metal complexes

Abstract Olefinplatinum(II) π-complexes can be synthesized by the following methods: (i) heating a solution of an olefin, alcohol or alkyl acetate and PtCl62− in acetic acid; (ii) light irradiation of a solution of PtCl62− and an olefin in acetone; and (iii) light irradiation of a solution of PtCl42− and an olefin in aqueous acetone. The possible mechanisms of the thermal and photoinduced reactions are discussed.

A 4 K matrix ESR study of the rearrangement and fragmentation of molecular radical cations of alkyl formates and acetates: Direct evidence for a McLafferty rearrangement

A 4 K matrix ESR study shows that the molecular radical cations of isopropyl formate and acetate, produced radiolytically in halocarbon matrices at 4.2 K, undergo spontaneous rearrangement due to a selective intramolecular hydrogen shift from the tertiary CH bond in the isopropyl group to the carbonyl oxygen atom giving RC +(OH)OC(CH 3) 2, where R = H or CH 3. The radical cation of tert-butyl acetate undergoes further fragmentation at the ester CO bond following a similar rearrangement to give an isobutene radical cation in CFCl 3.

Synthesis of 8-methoxy- and 8-methoxy-6-methylhomophthalic anhydrides, key intermediates for the synthesis of anthracyclinones and peri-hydroxylated polycyclic aromatic compounds.

A novel synthesis of 8-methoxy-(1a) and 8-methoxy-6-methylhomophthalic anhydrides (1b) is described. Oxidative aromatization of methyl 2-(2-carbomethoxy-3-oxocyclohex-1-enyl) acetate (2) using 2, 3-dichloro-5, 6-dicyano-1, 4-benzoquinone (DDQ) or sublimed sulfur followed by methylation gave methyl (2-carbomethoxy-3-methoxyphenyl) acetate (4) (method A). Diels-Alder reaction of 6-methoxy-4-methyl-2-pyrone (5) with 1, 3-dicarboalkoxyallenes occurred with the loss of carbon dioxide to give alkyl (2-carboalkoxy-3-methoxy-5-methylphenyl) acetates (6 and 7) (method B). These esters (4, 6, and 7) were converted to the corresponding 8-methoxyhomophthalic anhydrides (1a, b) by a usual alkaline hydrolysis followed by dehydrative cyclization with acetyl chloride in dry acetone.

Kinetics and mechanisms of the neutral and acid-catalysed hydrolyses of chloro-substituted alkyl acetates in aqueous solutions of constant ionic strength

The simultaneous neutral and acid-catalysed hydrolyses of different chloro-substituted alkyl acetates in water and in aqueous acetone solutions have been studied using electrolyte solutions of constant ionic strength. The mechanism of the acid-catalysed hydrolyses of monochloroesters is AAC2. When an ester has two chloro-substituents the acid-catalysed hydrolysis takes place simultaneously by the AAC2 and A–BAC3 mechanisms and in the case of trihalogenated esters the mechanism is A–BAC3, a mechanism with an unsymmetrically catalysed partition of the intermediate formed from the water-catalysed addition of water to the carbonyl group of the ester. Structural and solvent effects of these reactions are discussed.

Photoreduction des esters car☐yliques dans l'hexamethylphosphortriamide (HMPT)

Use of HMPT as solvent in photochemistry allows efficient photoreductions. Alkyl esters and especially non absorbing alkyl acetates are photoreduced in excellent yields into alkanes. In the latter case, a protonating agent is necessary. Numerous examples illustrate the generality and convenience of the reaction. This photoreduction involves an electron transfer from HMPT to ester.

ChemInform Abstract: Diastereoselection in 1,3‐O‐ to ‐C‐Alkyl Migration Reaction of 1‐Alkenyl Alkyl Acetals Catalyzed by Boron Trifluoride Etherate.

AbstractBei der Behandlung von (I) mit BF3 bei niedriger Temperatur erhält man über eine Isomerisierung zu den stereoisomeren Vinylethern (II) und (III) die isomeren Aldehyde (IV) und (V) in hohen Ausbeuten (75 ‐ 94 %), wobei je nach Substituenten unterschiedliche Anteile an erythro‐ und threo‐Form erhalten werden (erythro/threo von 98 : 2 bis 26 : 74).