Heptane as solvent

Optimization of the biotransformation showed that the best conditions for achieving high rates and molar conversions included the use of n-hexane and -heptane as solvents, a temperature of 50 °C, an equimolar concentration of the substrates around 50 mM, and a concentration of the lyophilized biocatalyst around 25-30 g/1. As a matter of fact, Table 6.1 shows how the carbon source affects the expressed activity of A. oryzae MIM and R. oryzae CBS 112.07. 

Anti addition has been observed in compounds which lack an allylic hydrogen that can participate in a 1,3-hydrogen shift as above. With heptane as solvent (25 °C, 1 atm), the hydrogenation of dimethyl bi-cyclo[2.2.2]oct-2-ene-2,3-dicarboxylate (21) yields 7.1% of the anti addition product (24) over a Pt/C catalyst, but only syn addition (22) occurs over Rh/C. ° An acidic medium (small amounts of a strong acid in methanol) has little effect on catalysis by Rh, but greatly increases the fraction of anti addition catalyzed by Pd/C, as much as 60% in the presence of p-TsOH. Evidence for the participation of the solvent was assumed to indicate a proton transfer to the alkyl intermediate with inversion of configuration at the attached carbon atom. 

George and Patel investigated some reversed-phase column packing materials for the presence of active silanol groups, by using the columns in the adsorption mode with -heptane as solvent. Four materials were tested for the analysis of theophylline and caffeine. These two compounds were well separated on all materials with the mobile phase acetonitrile - water - acetic acid (95 5 0.2). However, the sequence of caffeine and the internal standard 8-hydro-xypropyltheophylline varied for the columns. 

The use of secondary modifiers, e. g. quinoline, and the choice of solvent also play important roles in directing semi-hydrogenation selectivity. For example, in the hydrogenation of 1-octyne over a series of Pd/Nylon-66 catalysts metal loading had no effect on selectivity when the reaction was performed in n-heptane as solvent. When the same experiment was conducted in n-propanol, however, an inverse relationship between selectivity and catalyst metal loading was observed [56], This effect has been interpreted as a polar solvent-induced modification of the Pd active sites, which alters the relative adsorption behavior of the alkyne and alkene species [57], Modification by addition of quinoline is reported to benefit the selective production of a cij-vitamin D precursor from the related disubstituted alkyne [58] ... 

D9. We have a mixture of linoleic and oleic acids dissolved in methylcellosolve and 10% water. Feed is 0.003 wt frac linoleic acid and 0.0025 wt frac oleic acid. Feed flow rate is 1500 kgdi. A sinple countercurrent extractor will be used with 750 k h of pure heptane as solvent. We desire a 99% recovery of the oleic acid in the extract product. Equilibrium data are given in Table 13-3. Find N and the recovery of linoleic acid in the extract product. 

The slurry polymerizations of propene were carried out under constant pressure of propene (P=4 atm) in a BUCHI 2 I stainless steel reactor equipped with a turbine stirrer using heptane as solvent of the monomer. A scheme of the polymerization reactor is reported in figure 2. 

The resolution of primary amines with long-chain esters and their corresponding carboxylic acids has been less explored in comparison with the use of EtOAc and alkyl methoxyacetates. However, lauric acid (CJJH23CO2H) has served as an ideal acyl donor for the CAL-B-catalyzed resolution of aliphatic and aromatic amines at 80 °C using heptane as solvent (Figure 9.25) [196]. The use of carboxylic acids led to a marked acceleration of the reaction rates compared to their ethyl ester coxmterparts. 

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