Chain Aliphatic Ketones Research Articles

Thermodynamic Study on Density and Viscosity of Binary Mixtures of Ethyl acetoacetate with (C4-C9) Aliphatic Ketones at (303.15 and 308.15) K

Investigation on Density (ρ) and viscosity (η) of various binary mixtures of ethylacetoacetate and straight chain aliphatic ketones (butan-2-one, pentan-2- one, hexan-2-one, heptan-2-one, octan-2-one and nonan2-one) have been carried out over the entire solvents composition range at temperatures of 303.15K and 308.15K. From the data obtained, the excess molar volumes (V E ), the excess viscosity (η E ) and excess Gibbs free energy of activation for viscous flow (ΔG*E) have been calculated from the experimental density and viscosity measurements at the working temperatures. Excess molar volumes, V E results are negative and positive over the entire range of mole fractions and become more positive as the chain length increases. The excess viscosities, η E were both positive and negative over the entire mole fraction range. While the observed excess Gibbs free energies of activation of viscous flow, ΔG*E data are positive throughout the entire mole fraction range of solvents composition at all investigated temperatures. These observed results of the excess functions have been interpreted in terms of possible molecular interactions in the binary mixtures.

Screening, expression, and characterization of Baeyer-Villiger monooxygenases for the production of 9-(nonanoyloxy)nonanoic acid from oleic acid

In this study, the production of 9-(nonanoyloxy) nonanoic acid from oleic acid was investigated. The whole cell biotransformation of oleic acid includes OhyA (hydratase), ADH (alcohol dehydrdogenase), and BVMO (Baeyer-Villiger Monooxygenase) enzymes consecutively. BVMOs are known to catalyze oxidative cleavage of long chain aliphatic ketones (e.g., 2-decanone, 10-ketooctadecanoic acid). However, the enzymes are difficult to overexpress in a soluble form in microorganisms. Thereby, this study has focused on screening and functional expression of the BVMOs in Escherichia coli. Initially BVMOs were selected by protein sequence analysis and were examined for their ability to express in soluble and active form to generate 9-(nonanoyloxy)nonanoic acid from oleic acid. Secondly various optimization strategies of inducer concentrations, co-expression with molecular chaperones, and different media conditions were investigated. Among the 9 BVMOs screened, three BVMOs were found to produce the target product and among these, Di_BVMO3 isolated from Dietzia sp. D5 was found to be best. Further, the soluble expression of Di_BVMO3 was enhanced by adding phosphoglycerate kinase as N-terminal fusion tag. The whole cell biotransformation with fusion enzyme resulted in 3 ~ 5-fold enhancement in product formation compared with the non-fusion counterpart. Final productivity up to 105.3 mg/L was achieved. Besides Di-BVMO3, other two new BVMOs of Rh_BVMO4 from Rhodococcus sp. RHA1 and AFL838 from Aspergillus flavus NRRL3357 were screened for production of 9-(nonanoyloxy)nonanoic acid and could be used for whole cell biotransformation reaction of other long chain ketones.

Interactions of ethyl acetoacetate with some (C4–C9) aliphatic ketones at 298.15 K: Insight from volumetric studies

Density of binary mixtures of ethyl acetoacetate (EAA) with straight chain aliphatic ketones butan-2-one, pentan-2-one, hexan-2-one, heptan-2-one, octan-2-one and nonan-2-one were measured at varying compositions of the ethyl acetoacetate at 298.15K. The derived properties such as excess molar volumes, VmE, of the binary mixtures were calculated from the experimental density data of the mixtures. The calculated excess molar volumes were fitted into the Redlich-Kister polynomial to obtain the fitting parameters and standard deviations. The excess molar volumes of the binary mixtures investigated were negative over the entire range of composition. The negative values were attributed to dipole–dipole interactions between the unlike molecules of mixtures than those between the like molecules of the pure solvents. The observed negative values of the excess molar volumes for the studied binary mixtures were discussed in terms of intermolecular interactions which were present in the mixtures.

Catalytic hydrogen transfer over magnesia, IXa. reduction of long chain aliphatic ketones by 2-propanol

A series of symmetrical long chain aliphatic ketones of general formula CH3−(CH2)n-CO-(CH2)2−CH3, where n=4,5,6,7 and 8, has been used as hydrogen acceptors from 2-propanol at 573–723 K in the presence of MgO catalyst under flow conditions. The yeilds of the appropriate alcohols exceeded 50%. Above 623 K the consecutive dehydration of the alcohols formed took place with moderate yields leading to internal alkenes. The direct one-step synthesis of C13 alkene from 7-tridecanone has been realized under catalytic transfer reduction (CTR) conditions with high yield (>90%) over a MgO catalyst of enhanced acidity.

B-iso-2-(2-diethylaminoethyl)apopinocampheyl-9-borabicyclo-[3.3.1]nonyl hydride — An improved chiral reducing agent for straight chain aliphatic ketones

A series of chirally modified borohydrides of the type lithium B-iso-2-(alkyl)apopinocampheyl-9-borabicyclo[3.3.1]nonyl hydride ( 2–4 and 8–9) were prepared to enable a strategic development of chiral reagents for the reduction of straight chain aliphatic ketones. Reagent 8 (alkyl = 2-diethylaminoethyl) reduces 2-octanone in 82% ee, significantly higher than that obtained with NB-Enantride ( 7) under identical conditions. An improved methodology for these reductions is also described.

The loss of water from molecular ions of aliphatic ketones in electron‐impact mass spectra

AbstractIn a series of straight chain aliphatic ketones which has been studied, it has been shown that the structural requirement for loss of water from the molecular ions produced by electron‐impact is an alkyl group of seven or more carbon atoms attached to the carbonyl function.