Alkyl Methyl Research Articles

Experimental values and analysis of mixing heats of the binary mixtures formed by alkyl benzoates and n-alkanes

H E values for 28 binary mixtures of four alkyl (methyl, ethyl, propyl, and butyl) benzoates and seven odd n-alkanes (from pentane to heptadecane) were determined experimentally at 298.15 K. Data plots ( x, H E) revealed the endothermicity of the mixtures. For a given ester the endothermic effects increased regularly with n-alkane chain length and decreased regularly with the length of the alkylated chain of benzoate. The experimental values were analysed using two versions of the UNIFAC group contribution model. Using the new data, values were calculated for the specific interactions of the characteristic carboxyl group, COO, on the benzoates with other groups in the mixing process for these mixtures, namely, CH 2 COO and ACH COO . Using the new values the model produced good H E estimates, with an overall mean error of less than 5%.

Novel Copolymers of Trisubstituted Ethylenes with Styrene. I. Alkyl and Alkoxy Phenyl Substituted Methyl 2-Cyano-3-phenyl-2-propenoates

Novel Copolymers of Trisubstituted Ethylenes with Styrene. I. Alkyl and Alkoxy Phenyl Substituted Methyl 2-Cyano-3-phenyl-2-propenoates

On the selectivity of stannylene-mediated alkylation and esterification of methyl 4,6- O-benzylidene α- d-glucopyranoside

On the selectivity of stannylene-mediated alkylation and esterification of methyl 4,6- O-benzylidene α- d-glucopyranoside

ChemInform Abstract: Stereoselective Alkylation of Methyl‐(2‐tributylstannyl) tetrahydrofuran‐3‐ylcarboxylate Lithium Enolate: Access to 2,3,3‐ Trisubstituted Tetrahydrofurans.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

1994 Syntex Award Lecture: Anionic Electrophiles, Protein Modification, and Artificial Blood

Monomethyl esters of acyl phosphates (mixed anhydrides of carboxylic and phosphoric acids) are being developed as site-directed acylating agents for amino groups in proteins. In an illustrative application, these anionic materials are shown to bind to a positively charged region of hemoglobin where they convert amino groups to amides. Bifunctional acyl methyl phosphates cross-link hemoglobin to give a variety of products, some of which have the oxygen-binding properties anticipated for materials that can serve as an alternative to red cells in transfusions. Higher yields of desired products result from the use of a trifunctional analogue. Kinetic patterns of the reactions of a series of alkyl amines and methyl aroyl phosphates indicate that the transition state for formation of the amide involves almost complete development of positive charge on nitrogen.

Synthesis of new hydantoin-3-ethanethiol derivatives

5-sec-Butylthiomethyl-5-alkyl (methyl or phenyl) hydantoins (3−x) were prepared by the reaction of sec-butylthiomethyl alkyl (methyl or phenyl) ketone (1–2), potassium cyanide and ammonium carbonate. 3-(2-Bromoethyl) hydantoins (5–6) were the reaction products of 5-sec-butylthiomethyl-5-alkyl (methyl or phenyl) hydantoin and 1,2-dibromoethane in the presence of potassium hydroxide. Alkylation of5 and6 with an excess of alkyl (methyl or ethyl) iodide in THF with sodium hydride as base gave three 1-alkyl (methyl or ethyl)-3-(2-bromoethyl) hydantoins (7–9). Treatment of the 2-bromoethyl group with potassium thioacetate and triethylamine gave three 1-alkyl (methyl or ethyl)-3-(2-acetylthioethyl) hydantoins (10–12). Hydrolysis of the 2-acetylthioethyl group with sodium hydroxide in methanol afforded the three 1-alkyl (methyl or ethyl)-3-(2-mercaptoethyl) hydantoins.

Stereoselective alkylation of methyl (2-tributylstannyl)tetrahydrofuran-3-ylcarboxylate lithium enolate:- Access to 2,3,3-trisubstituted tetrahydrofurans

A stereoselective synthesis of 2,3,3-trifunctionalised tetrahydrofurans is described.

Thermal decomposition of copolymers of methyl methacrylate and alkyl methacrylates obtained from a CSTR

Thermal decomposition of the copolymers of methyl methacrylate (MMA) with ethyl methacrylate (EMA) or n-butyl methacrylate (BMA) were investigated. The copolymers were obtained in a continuous stirred tank reactor (CSTR) using toluene and benzoyl peroxide, as solvent and initiator, respectively, at 80C. The volume was 1.2 litters and residence time was 3 hours. The thermal decomposition followed the second order kinetics for both MMA/EMA and MMA/BMA copolymers, which were almost in accordance with the order of copolymerization in a CSTR. The activation energies of thermal decomposition were in the ranges of 32-37 kcal/mol and 27-37 kcal/mole for MMA/EMA and MMA/BMA copolymers, respectively and a good additivity rule was observed against each composition for both copolymers. The thermogravimetric trace curve agreed well with the theoretical calculation.

Selective Enzymatic Hydrolysis of Phenolic Acetates

Phenolic acetates are selectively hydrolyzed in the presence of alkyl acetates, methyl esters and cinnamates with pig liver acetone powder (PLAP).

Enantioselective reduction of ketones catalysed by 1,3,2-oxazaborolidines prepared from phenylglycine

( R)- B-methyl-4,5,5-triphenyl-1,3,2-oxazaborolidine ( 1) and ( R)- B-allyl-4,5,5-triphenyl-1,3,2-oxazaborolidine ( 2), prepared from ( R)-phenylglycine, catalyse the reduction of prochiral ketones with borane, to afford the corresponding secondary alcohols in good chemical yields and with moderate to high (61%–96%) enantiomeric excesses. These compounds gave the best results reported so far regarding the reduction of linear alkyl methyl ketones catalysed by oxazaborolidines.

ChemInform Abstract: Branched Long Chain Alkyl Methyl Ethers: A New Class of Lipids from Spider Silk

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Excess molar volumes for binary systems containing toluene, p-xylene or pseudo-cumene + five methyl alkyl ketones at 298.15 K. Application of an extended cell model

Excess molar volumes at 298.15 K are reported for the binary systems containing toluene, p-xylene or pseudo-cumene + 2-propanone, 2-butanone, 2-pentanone, 2-octanone or 2-undecanone. All experimental curves present negative excess volumes, with the sole exception of the pseudo-cumene(1) + 2-propanone(2) mixture. The experimental data are examined by an extended cell model.

Practical synthesis and regioselective alkylation of methyl 4(5)-(pentafluoroethyl)-2-propylimidazole-5(4)-carboxylate to give DuP 532, a potent angiotensin II antagonist

DuP 532 (2), which is a potent angiotensin II receptor antagonist, has been prepared by two different routes. One route, which is more practical for large-scale synthesis, required the preparation of methyl 4(5)-(pentafluoroethyl)-2-propylimidazole-5(4)-carboxylate (9). This imidazole war synthesized in five steps from commercially available 11 in 32% overal yield. Alternate perfluoroalkylation methods of the iodoimidazole precursor 14 are presented. Imidazole 9 is remarkably stable to basic conditions and is alkylated by 2-[N-(triphenylmethyl)tetrazol-5-yl]-4'-(bromomethyl)-1,1'-biphenyl (8), giving only the desired regioisomer. A comparison of the alkylation of the trisubstituted precursors and analogues to 9 with 8 indicate that even under mildly basic conditions (K 2 CO 3 /DMF), the mechanism is S E 2cB (anionic), except for 2-propyl-4(5)-(hydroxymethyl)imidazole (11) which alkylates as a neutral species (S E 2')

Branched long chain alkyl methyl ethers: a new class of lipids from spider silk

Long chain methyl branched 1-methoxyalkanes, a new class of ether lipids, have been identified from silk of the spider Linyphia triangularis (Araneae: Linyphiidae) by use of gas chromatographic retention indices, GC/MS investigations, and chemical modifications. Methyl groups are predominantly located at C-2, and ω-3 or ω-2 positions, respectively. Chain length varies between C 24 and C 32. The synthesis of representative compounds is reported.

Antiviral phospholipids. Anti-HIV drugs conjugated to the glycerobackbone of phospholipids.

Heteroatom fatty acid analogs of myristic acid containing oxygen or sulfur substituted for the alkyl methylene groups inhibit replication of the human immunodeficiency virus (HIV) in infected cells by acting as alternative substrates during the viral protein myristoylation event. In this class of compounds, 12-methoxydodecanoic acid is the most potent compound but is approximately 10(3)-fold less active than azidothymidine. The antiviral activity of 12-methoxydodecanoic acid can be enhanced > 40-fold by preparing L-alpha-phosphatidylethanolamine containing 12-methoxydodecanoic acid in both alkyl chains. In addition, the diacylated L-alpha-phosphatidylcholine analog containing 12-methoxydodecanoic acid in both alkyl chains (i) has a 15-fold better antiviral selectivity, (ii) is 7-fold more potent, and (iii) is 10-100-fold more synergistic with azidothymidine than 12-methoxydodecanoic acid. Because of potent synergism, the antiviral selectivity of the diacylated L-alpha-phosphatidylcholine analog is > 10(4) when coadministered with azidothymidine. Phospholipid conjugates are chiral at the C-2 carbon of the glycerol backbone and most interesting is the observation that both the D- and L-isomers of phosphatidylcholine, phosphatidylglycerol, phosphatidic acid, and phosphatidylserine have approximately equal antiviral activity. Phospholipase A2 stereospecifically hydrolyzes only the L isomer of phospholipids and similar activity for both the D- and L- phospholipid isomers suggests that phospholipase A2 is not the rate-limiting enzyme for release of the drugs in vivo.

Solution copolymerization of methyl methacrylate and alkyl methacrylates in a continuous stirred tank reactor(CSTR)

Continuous solution copolymerization of methyl methacrylate with ethyl methacrylate or n-butyl methacrylate was carried out in a continuous stirred tank reactor. Solvent and initiator used were toluene and benzoyl peroxide, respectively. Reaction volume was 1.2 litters, residence time 3 hours and polymerization temperature 80°C. The copolymerization conversions were analyzed by UV spectrophotometry and confirmed by measuring the solid weights of copolymers obtained after evaporating solvent. The copolymerization of methyl methacrylate and alkyl methacrylates followed the second order kinetics. The simulated conversions and copolymerization rates were compared with the experimental results. The average time to reach dynamic steady-state was three and half times of the residence time.

Synthesis of alkyl glycoside fatty acid esters in non‐aqueous media byCandida sp. lipase

Alkyl glycoside fatty acid esters were successfully synthesized by lipase‐catalyzed transesterification of methyl glucoside, methyl glucoside, methyl galactoside and octyl glucoside with methyl oleate. The experiments were carried out in organic media with lipase enzymes fromCandida sp. as biocatalysts. Time course and the effects of temperature, solvent type, substrate concentration, added water and of immobilizedvs. nonimmobilized enzyme were studied. The optimal conditions for the enzymatic synthesis of alkyl glycoside fatty acid esters were: a molar ratio of alkyl glycoside and methyl oleate of 1:4, an immobilized lipase, SP382 fromCandida sp.; benzene/pyridine (2:1, vol/vol) with no added water; temperature, 55°C; reaction time, 48 h; and shaking at 200 rpm. Acceptable levels of oleic acid incorporation (58.6–100 mol%) onto the alkyl glycosides were achieved.

Die reaktion von silyl-bis(trifluormethansulfonaten) mit diazoessigestern und diazomethyl-ketonen

Equimolar amounts of diazoacetates and dialkylsilyl-bis(trifluoromethanesulfonates) (alkyl  methyl, i-propyl, t-butyl) in the presence of a tertiary amine yield [(trifluoromethylsulfonyloxy)-dialkylsilyl]diazoacetates, whereas a 2/1 molar ratio of the reactants leads to dialkylsilyl-bis(diazoacetates). In the former products, nucleophilic substitution of the trifloxy group by an alcohol readily yields [alkyloxy- (or alkenyloxy-, alkinyloxy-) dialkylsilyl]diazoacetates. With enolizable ketones, O-silylation occurs, and [(1-alkenyloxy)-dialkylsi are obtained. When diazomethyl ketones are reacted with dialkylsilylbis(trifluoromethanesulfonates), the corresponding dialkylsilyl-bis (diazomethyl ketones), [R 1 2Si(CN 2COR 2) 2], rather than 1 : 1 products are obtained in most cases studied. Except for derivatives having sterically demanding substituents R 2 these 2 : 1 products are rather unstable in solution; furthermore, removal of the solvent results in decomposition to a mixture of unidentifiable products. When di-(t-butyl)silyl-bis(trifluoromethanesulfonate) is combined with 1-diazo-3,3-dimethyl-2-butanone or 1-(1-adamantyl)-2-diazo-1-ethanone, 1 : 1 adducts most likely result, which undergo further reaction with excess diazoketone to yield a pyrazole or a tetrazole, respectively. These heterocycles have been identified by X-ray structure analysis.

Preparation of Bicyclic Herbicide Precursors by Intramolecular Stork-Danheiser Kinetic Alkylation Reactions of Methyl 1-(Haloalkyl)-3-methoxy-5-oxocyclohex-3-ene-1-carboxylate Derivatives

Reductive alkylation of methyl 3,5-dimethoxybenzoate with the dibromoalkane and the bromochloroalkane derivatives (4a-d) and (4e-g) afforded, after acid hydrolysis, the corresponding methyl 1-( haloalkyl )-3-methoxy-5-oxocyclohex-3-ene-1-carboxylate derivatives (6a-g). Reaction of (6a-c) with lithium diisopropylamide afforded methyl 3-methoxy-5-oxobicyclo[4.2.0]oct-3-ene- 1-carboxylate (2a), methyl 5-methoxy-7-oxo-1,2,3,4,7,7a-hexahydro-3aH-indene-3a-carboxylate (2b) and methyl 6-methoxy-8-oxo-1,3,4,5,8,8a-hexahydronaphtha1ene-4a(2 H)- carboxylate (2c), respectively. Compounds (2b) and (2c) were also obtained from the reaction of (6f) and (6g) with lithium diisopropylamide . Compounds (2a) and (2b) were each obtained as a single bridgehead isomer, the relative stereochemistry of ring fusion of which was assigned as cis on the basis of semiempirical molecular orbital calculations. Compound (2c) was obtained as a mixture of cis-and trans-fused bridgehead isomers. The ester (2b) was converted into the herbicide methyl 5,7-dioxo-6-[1-[(prop-2-enyloxy) imino ] butyl]octahydro-3aH-indene-3a-carboxylate (3a).

The regioselectivity of the ring opening of 1‐activated or nonactivated 2‐alkoxycarbonyl or 2‐cyanoaziridines by carbanions of the dicarbonyl compounds

AbstractRing opening of title compounds with alkyl malonates, acetylacetone, methyl acetylacetate, and malononitrile was studied. The regioselectivity of the opening depends on several factors. A phenyl group on C3 favours C3N bond cleavage, whereas C2N bond cleavage is predominant with C3‐substituted or C2H aziridines. Cyanoaziridines are predominantly cleaved at C3N. The aziridine configuration at C2 and C3 is maintained during the cyclisation in pyrrolidones.