Fractional esterification rate

CER The fractional esterification rate (FER) is calculated as [cpm [3H] cholesteryl esters/(cpm [3H]cholesteryl esters + cpm unesterified [3H] cholesterol)]. 

Dobiasova M, Frohlich J (1996) Measurement of fractional esterification rate of cholesterol in plasma depleted of apoprotein containing lipoprotein methods and normal values. Physiol... 

As can be seen in Fig. 1, ApoD in fact activates LCAT. The reactivity of ApoD, expressed as fractional esterification rate (FER) per incubation time, is about 30% that of ApoA-I. The reaction proceeds linearly up to 60 min, whereas in proteolipo-somes with ApoA-I, FER increases faster, but then the curve levels off. One possible explanation of this might be that ApoD stabilizes the LCAT during this reaction. 

Diethyl Malonate. 200 kilos of the above powder (sodium malonate can be purchased cheaply without alarming DBA officials. I gave the above formula for do-it-yourselfers) is stirred with 160 kilos of ethanol (industrial spirit) and 500 kilos of benzene in an esterification kettle. About 240 kilos of coned sulfuric acid are added, at such a rate that the temp of this well stirred mixture never exceeds 25° (this will take several hours for a formula this big). The temp is then raised to 60° and maintained for at least 8 hours and then cooled. The top benzene layer is removed and the lower acid layer is extracted with benzene repeatedly. The combined benzene layers are washed free of acid, with dilute sodium hydroxide, and dried over anhydrous sodium carbonate and then distilled under vacuo (20 mm). The fraction boiling at 96-98° is collected as commercially pure diethyl malonate. Yield 85-90% of theoretical. 

If the DDM reaction is carried out at sufficiently low temperatures for the ester formed not to undergo subsequent ionization, the fraction of ester (R) in the total products of esterification and solvolysis is given by the ratio A i/(fc i in scheme 9. The rate constant i i refers to ion pair collapse, or return, and refers primarily to ion-pair dissociation, though it also incorporates the rate of any reaction that leads to solvolysis... 

Investigations of Mucor miehei lipase-catalyzed esterifications in SCCO2 showed that a pressure increase from 100 to 250 bar reduced the initial reaction rates from 23 to 8 pmol per gram enzyme and per hour, parallelling the decreasing mole fraction of substrates (Scheme 4.9-1) [22]. 

The set of Equations 25.42-25.48 can be solved provided the following information is available vapor-liquid equilibrium data, for example, the ternary equilibrium data for a typical esterification reaction mass and enthalpy balances around the feed point, reflux inlet, and reboiler to account for the flow rates, compositions, and thermal conditions of the external streams mass transfer coefficients in the absence of reaction (either by experimental determination or estimation from available correlations) liquid holdup (usually from available correlations) and an expression for the reaction rate. Then the equations can be solved by any convenient method, preferably the Runge-Kutta routine, to get the mole fraction of each component as a function of height. 

As is typical for step-growth polymerizations, each molecule in the reaction mixture has two reactive -OH groups, and for each H2O molecule lost, one bond is formed. Furthermore, [H ] is also proportional to [-OH] if no external acid is added. In Fig. 3.19 a kinetics is assumed, similar to the just discussed third-order esterification (n = 3). This assumption is next shown to fit the measured data. Writing for the concentration [POH] = [POH]o(l - p), where [POHl is the initial concentration (= 2Mo) and p the fractional progress of the polymerizarion, one can see that the rate of polymerization dp/dt = k[POH](, (l - p)l The connection to the boxed equation is given by k = k[POH]/. Also, written is the temperature-dependence of k as described in Fig. A.7.2. 

The large excess of methanol was taken in this study due to the low solubility of glutaric acid in methanol. The kinetic data which had been determined experimentally for the esterification were correlated with quasi-homogeneous (QH) model (Schmitt Hasse, 2006). Comparing with the experimental values, the QH model represents well the conversions of glutaric acid and the mole fractions of each constituent component varying with the contact time. The values of the rate constants were determined by fitting the kinetic data to the reaction rate expressions simultaneously. The temperature dependent fei, k2, fe, ki were listed in Table 3,... 

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