Isopropyl alcohol

About: Isopropyl alcohol is a(n) research topic. Over the lifetime, 3064 publication(s) have been published within this topic receiving 27354 citation(s). The topic is also known as: Rubbing Alcohol & Propan-2-ol.

Ru(arene)(amino alcohol)-Catalyzed Transfer Hydrogenation of Ketones: Mechanism and Origin of Enantioselectivity

Abstract: The mechanism of the Ru(arene)(amino alcohol)-catalyzed transfer hydrogenation of ketones using isopropyl alcohol as the hydrogen source has been studied by means of hybrid density functional methods (B3PW91). Three mechanistic alternatives were evaluated, and it was shown that the reaction takes place via a six-membered transition state, where a metal-bound hydride and a proton of a coordinated amine are transferred simultaneously to the ketone. Further calculations provided a general rationale for the rate of the reaction by comparison of steric effects in the ground and transition states of the ruthenium hydride complex. It was found that the TS has a strong preference for planarity, and this in turn is dependent on the conformational behavior of the O,N-linkage of the amino alcohol ligand. Finally, a general model, rationalizing the enantioselectivity of the reaction, was developed. Experimental studies of both rate and enantioselectivity were used in order to support the computational results.

Extraction of ginger (Zingiber officinale Roscoe) oleoresin with CO2 and co-solvents: a study of the antioxidant action of the extracts

Abstract: The effects of temperature, pressure and the addition of co-solvent (ethanol (EtOH) and isopropyl alcohol (IsoC3), both at 1.17% (mass)) on the kinetics of extraction of ginger oleoresin were studied. The design used was a 2×2×3 factorial (pressure 200 and 250 bar; temperature: 25 and 35 °C; solvent: CO2, CO2+EtOH, CO2+IsoC3). The experimental setup used was a fixed bed extractor with diameter of 2.76×10−2 m and length of 0.387 m. The assays were carried out at a mean solvent flow rate of 5.86×10−5 kg/s and with a bed apparent density of 350 kg/m3. The identification of the substances present in the oleoresin was performed by GC-MS; GC-FID was used to determine the ginger extract compositions. The antioxidant activity of the extract fractions was determined using the coupled oxidation of linolenic acid and β-carotene. The results show that the temperature and the interaction of the pressure and the solvent significantly affected the total yield. For the mass transfer rate, the effect of the interaction of the pressure and the solvent was significant; the mass transfer rate increased with the pressure in the absence of the co-solvent and decreased when ethanol and isopropyl alcohol were used. The major substances present in the ginger extracts were α-zingiberene, gingerols and shogaols; the amounts of these compounds were significantly affected by temperature, pressure and solvent. Nonetheless, the antioxidant activity of the ginger extracts remained constant at ≈80% and decreased to ≈60% in the absence of gingerols and shogaols. The Sovova's model quantitatively described the overall extraction curves.

Metabolic Engineering of Clostridium acetobutylicum ATCC 824 for Isopropanol-Butanol-Ethanol Fermentation

Abstract: Clostridium acetobutylicum naturally produces acetone as well as butanol and ethanol. Since acetone cannot be used as a biofuel, its production needs to be minimized or suppressed by cell or bioreactor engineering. Thus, there have been attempts to disrupt or inactivate the acetone formation pathway. Here we present another approach, namely, converting acetone to isopropanol by metabolic engineering. Since isopropanol can be used as a fuel additive, the mixture of isopropanol, butanol, and ethanol (IBE) produced by engineered C. acetobutylicum can be directly used as a biofuel. IBE production is achieved by the expression of a primary/secondary alcohol dehydrogenase gene from Clostridium beijerinckii NRRL B-593 (i.e., adhB-593) in C. acetobutylicum ATCC 824. To increase the total alcohol titer, a synthetic acetone operon (act operon; adc-ctfA-ctfB) was constructed and expressed to increase the flux toward isopropanol formation. When this engineering strategy was applied to the PJC4BK strain lacking in the buk gene (encoding butyrate kinase), a significantly higher titer and yield of IBE could be achieved. The resulting PJC4BK(pIPA3-Cm2) strain produced 20.4 g/liter of total alcohol. Fermentation could be prolonged by in situ removal of solvents by gas stripping, and 35.6 g/liter of the IBE mixture could be produced in 45 h.

Extraction and characterization of mucilage in Opuntia spp.

Abstract: The cactus pear (Opuntia ficus indica) mucilage is an interesting ingredient for the food industry because of its viscosity properties. We studied the conditions for the extraction and precipitation of the plants mucilage. Extraction conditions were: pad/water ratios (1:51:7), extraction temperature, (40±2 and 16±2 °C) and extraction time (4, 8 and 16 h). For the precipitation of the mucilage two types of alcohol (ethanol and isopropyl alcohol) and two water/alcohol ratios (1:3 and 1:4) were used. No differences were found in any of the measured variables among the different extraction or precipitation methods. The average mucilage yield after drying was 1.48% based on fresh weight (f.w.) and 19.4% based on dry weight (d.w.). The dried mucilage had in average 5.6% moisture; 7.3% protein; 37.3% ash; 1.14% nitrogen; 9.86% calcium and 1.55% of potassium. The colour analysis showed a high L* value and the chromatic co-ordinates were in the yellow-greenish spectrum. The use of isopropyl alcohol is recommended in ratio 1:3, since its commercial value is lower in comparison with ethanol.

On the mammalian acetone metabolism: from chemistry to clinical implications.

Abstract: Despite the description of the ways of acetone metabolism, its real role(s) is (are) still unknown in metabolic network. In this article, a trial is made to ascertain a comprehensive overview of acetone research extending discussion from chemistry to clinical implications. Mammals are quite similar regarding their acetone metabolism, even if species differences can also be observed. By reviewing experimental data, it seems that plasma concentration of acetone in different species is in the order of 10 microm range and the concentration-dependent acetone metabolism is common to all mammals. At low concentrations of plasma acetone, the C3 pathways are operative, while at higher concentrations, the metabolism through acetate becomes dominant. Glucose formation from acetone may also contribute to the maintenance of a constant blood glucose level, but it seems to be only a minor source for that. From energetical point of view, an interorgan cooperation is suggested because transportable C3 fragments produced in the liver can serve as alternative sources of energy for the peripheral tissues in the short of circulating glucose. The degradation of acetoacetate to acetone contributes to the maintenance of pH buffering capacity, as well. Special attention is paid to the discussion of acetone production in diseases amongst which endogenous and exogenous acetonemiae have been defined. Acetonemiae of endogenous origin are due to the increased rate of acetone production followed by an increase of degrading capacity as cytochrome p450IIE1 (CYPIIE1) isozymes become induced. Exogenous acetonemiae usually resulted from intoxications caused by either acetone itself or other exogenous compounds (ethanol, isopropyl alcohol). It is highlighted that, on the one hand, isopropanol is also a normal constituent of metabolism and, on the other hand, the flat opinion that the elevation of its plasma level is a sign of alcoholism cannot further be held. The possible future directions of research upon acetone are depicted by emphasizing the need for the clear-cut identification of mammalian acetoacetate decarboxylase, and the investigation of race differences and genetic background of acetone metabolism.