Pentane product

Sagai M. Tappel AL. 1978. Effects of vitamin E on carbon tetrachloride- induced lipid peroxidation as demonstrated by in vivo pentane production. Toxicol Lett 2 149-155. 

It is evident that we have produced one of our desired products here, nearly pure pentane. We now have to separate the near-azeotropic stream, p2. An ideal situation occurs if we can recycle it back to the liquid/liquid extractor. If its composition is close to that of the original feed to the process, we could simply mix it with the feed. Our two separation devices then would process this feed, giving us a pure pentane product and, by material balance, a second stream which is the feed but with this same amount of pentane missing. 

Let us examine what we have accomplished with the liquid/liquid extraction step followed by the two distillation columns. The upper column, DI-2, produces essentially a pure pentane product, which we remove. The lower column, DI-3, produces a product with no pentane. We recycle all the other streams... 

The results in table 10 refer to initial catalytic activity 10 mins after addition of the hydrocarbon to the stream. The trend in all cases is for hydrogenation activity to subside with time. The final column contains data from an optimally conditioned catalyst for comparison. It is concluded that in order to minimize pentane production and maximize branched product the catalyst should be exposed to H2/H20 prior to admission of 1-pentene. 

Catalytic Percent Decane lso- n-Butane lso- n-Pentane Products,... 

Example 14.3. Consider the separation problem shown in Fig. 1.18, except that separate isopentane and n-pentane products are also to be obtained with 98% recoveries. Use heuristics to determine a good sequence of ordinary distillation units. 

We are separating 1000 kmol/h of a feed containing propane, n-butane, and n-pentane. The feed pressure is 4.0 atm This feed is 22.4 mol% propane, 44.7 mol% n-butane, and the remainder n-pentane. In the overall process we plan to recover 99.6% of the propane in the propane product, 99% of the n-butane in the n-butane product, and 99.7% of the n-pentane in the n-pentane product. In column 1 recover 99.5% of the n-butane in the bottoms product. For purposes of your initial mass balances, assume 1) There is no n-pentane in the propane product stream, and 2) There is no propane in the n-pentane product stream Check these guesses after you have run the simulations. Both columns operate at 4.0 atm Operate each column at 1.15 L/D minimum Use the optimum feed stage for each column. 

The objective function (economic value) representing the economic operating margin for the column is shown in Figure 14.2, which is defined as the difference between the value of products (top butane product and pentane bottom pentane product) and costs of feed and energy. The value function features two discontinuities. The first, which occurs when the composition of the bottom product is about 1 % butane, corresponds to a change in the top product from off-spec to on-spec. The second discontinuity occurs when the bottom product becomes off-spec at 5% butane. 

To choose the bottom temperature target, first assume that the reflux rate is fixed, and that the bottom product is on-spec, but the top product off-spec because of its high pentane content. This would correspond to a very hot bottom temperature. When the bottom temperature is slowly reduced, the amount of bottom produet inereases, but the percentage of butane in the bottom also increases simultaneously. As the amount of pentane product increases, the total product value improves. The middle line in Figure 14.2 represents this operation. 

Pattee HE, Singleton JA, Johns EB (1974) Pentane production by peanut lipoxygenase. Lipids 9 302-306... 

Too much feed preheat, therefore, can make it impossible to meet bottoms product specifications. Thai s why experienced operators hold a constant feed temperature. Unfortunately, for certain systems a very large increase in percent vaporized (and hence enthalpy) occurs for a small change in temperature. As an example, consider a tower with a feed composition of 2% propane, 72% butane, 24% pentane, and 2% hexane. A few degrees extra preheat in this tower s feed caused a large increase in the amount of butane vaporized. This led to a considerable drop in stripping vapor rate and a consequent increase in butane in the bottoms pentane product. 

Endo-exo ratios of the micelle-catalysed reactions have been determined by adding 0.25 mmol of 5.1c and 0.5 mmol of 5.2 to a solution of 5 mmol of surfactant and 0.005 mmol of EDTA in 50 ml of water in carefully sealed 50 ml flasks. The solutions were stirred for 7 days at 26 C and subsequently freeze-dried. The SDS and CTAB containing reaction mixtures were stirred with 100 ml of ether. Filtration and evaporation of the ether afforded the crude product mixtures. Extraction of the Diels-Alder adducts from the freeze-dried reaction mixture containing C12E7 was performed by stirring with 50 ml of pentane. Cooling the solution to -18 C resulted in precipitation of the surfactant. Filtration and evaporation of the solvent afforded the adduct mixture. Endo-exo ratios... 

In some experiments the presence of hexane is undesirable in view of the volatility of the products. In these cases one can use butyllithium in pentane (prepared from butyllithium in hexane, by replacing the hexane with pentane see Exp. 10) or ethyllithium in diethyl ether, prepared from ethyl bromide and 11thiurn (see Exp. 1). 

High vacuum distillation gave a crystalline product, containing small amounts of impurities, inter alia some 2-butynoic acid. Crystallization from a 3 1 mixture of pentane and diethyl ether at low temperature gave the pure acid, m.p. 77°C, in 38-45 yields. 

Note 7. To a solution of 0.55 mol of sodium hydroxide in 150 ml of methanol and 40 ml of water was added a cold solution of 0.55 mol of methanethiol in 50 ml of methanol with cooling below 10°C. Subsequently 0.50 mol of propargyl chloride was added with swirling in 15 min, while keeping the temperature between 20 and 40°C. After an additional 30 min 1 1 of water was added and the product was extracted six times with small amounts of pentane. The extracts were washed with water, dried and the solvent was... 

The greater part of the hexane and THF was removed in a water-pump vacuum, using a rotary evaporator. To the remaining white salt mass was added a solution of 30 g of kOH in 175 ml of 96 ethanol. The mixture was heated at 60°C for 30 min, then 500 ml of ice-water were added. The organic products were extracted six times with redistilled pentane, then washed with water and dried over magnesium sulfate. 

To a solution of 0.5D mol of KO-tert.-C Hg (uncomplexed base, commercially available) and 180 ml of dry THF was added at room temperature 0.25 mol of the Mannich product. A weakly exothermic reaction took place. The mixture was heated in a bath at 50°C and the THF started to reflux (occasional cooling in an ice-water bath may be necessary). When the refluxing had ceased, the mixture was heated for 30 min in a bath at 70°C, then cooled to room temperature and 300 ml of redistilled, dry pentane were added. The precipitate of potassium raethoxide and... 

It was dissolved in 75 ml of pentane and the solution was cooled to about -30°C with swirling. Some oil precipitated NHR spectroscopy showed the presence of only a very small amount of the allene. The supernatant yellow liquid was decanted from the oil and, after some pentane had been removed by evacuation, the solution was cooled below -40°C. The pale yellow crystals (m.p. 52°C) were filtered off on a sintered-glass funnel (note 2). From the mother liquor an additional small amount of product was obtained, bringing the yield of NMR-pure material to 62%. 

After cooling to about 40°C (note 2) the viscous brown liquid was poured into a vigorously stirred solution of 50 g of ammonium chloride in 250 ml of 4 N HCl, which was kept at 0-5°C. The flask was also rinsed with this solution. The product was extracted 5-7 times with a 1 1 mixture of diethyl ether and pentane. The combined extracts were washed with saturated NHi Cl solution and subsequently dried over magnesium sulfate. The residue remaining after removal of the solvents in a water-pump vacuum, was carefully distilled through a 30-cm Widmer column. The desired nitrile, b.p. 84°C/15 mmHg, n 1.4487, was obtained in 72% yield. The first fraction (about 5 g) consisted mainly of the 1,3-substitution product n-C,HgC(CsN)=C=CH2. 

Alkanes spontaneously burst into flame in the presence of elemental fluonne The reaction that takes place between pentane and F2 gives CF4 and HE as the only products... 

Hydroxy 2 propylheptanal (aldol addition product of pentanal)... 

Product of aldol addition of pentanal (3 hydroxy 2 propylheptanal)... 

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