Least separation temperature

The separation temperature should be chosen to be at least 5 to 10°C above saturation temperature to prevent floating with the liquid CO2 and to ensure that the precipitated extract is under liquid conditions. 

The least reactive coinitiator is EtjAl. Reactions coinitiated with EtjAl are least affected by temperature. The increase in temperature from — 80° to — 65° slightly increases the conversion. Increased amounts of first generation products indicate that this is due to an increased rate of initiation. From — 65° to — 30° conversions remain fairly constant in any solvent. EtsAl, the weakest Lewis acid studied, probably gives the most nucleophilic counter anion, and consequently the least separated ion pair which would explain fast ethylation or hydridation (termination) ofthet-Bu . 

A number of parameters determine whether or not the morphology of interest is adopted by a microphase separating copolymer melt. Of these, most important are the interaction parameter, the volume ratio of the blocks, the degree of polymerization, the individual block molecular weight distributions, the overall polydispersity, the interactions with the interfaces, and last but not least, the temperature. Only the latter two parameters are experimentally accessible and can be altered after the synthesis of the copolymer (disregarding polymer blends). Control over the self-assembly at the film interfaces becomes essential when the polymer films are intended to be used as templates. Meuler et al. recently published a comprehensive review on how these various parameters affect the formation of gyroid-like morphologies in polymeric materials [47]. 

Temperature also has a pronounced effect on chiral selectivity, in general, the lower the temperature the better the chiral selectivity. In method development, it is necessary to determine both the retention ratio and the separation ratio at least at temperatures 5°C, 15°C and 25°C. 

In the hydrophobic encapsulation experiments, phospholipid DPPE-DVBA was used as representative lipid. The encapsulation experiment was conducted at two separate temperatures, 55 °C and at 10 °C [DPPE-DVBA phospholipid (2.5 mg/temperature), 5 mg total]. DPPE-DVBA was dissolved in chloroform to form a homogenous solution, then the solvent was evaporated under a gentle stream of nitrogen. The thin layer was dried under vacuum for at least 3 h. The thin lipid film was covered with 0.05 M NaHCOa/O.l M NaOH. Lipid... 

The thermal history has a profound influence on the DSC curves of polymer blends containing at least one crystalline component. In order to obtain by DSC experiments, the samples are usually first heated to a temperature between the phase separation temperature and the melting point of the crystalline component and held for several minutes to remove the thermal history. 

Place 200 g. (172 -5 ml.) of redistilled furfural (1) in a 1 litre beaker, provided with a mechanical stirrer and surrounded by an ice bath. Start the stirrer and, when the temperature has fallen to 5-8°, add a solution of 50 g. of sodium hydroxide in 100 ml. of water from a separatory funnel at such a rate that the temperature of the reaction mixture does not rise above 20° (20-25 minutes) continue the stirring for a further 1 hour. Much sodium furoate separates during the reaction. Allow to cool to room temperature, and add just enough water to dissolve the precipitate (about 65 ml.). Extract the solution at least five times with 60 ml. portions of ether in order to remove the furfuryl alcohol the best results are obtained by the use of the continuous extraction apparatus (charged with 350 ml. of ether) depicted in Fig. //, 44, 2. Keep the aqueous layer. Dry the ethereal extract with a httle anhydrous... 

Acetone in conjunction with benzene as a solvent is widely employed. With cyclohexanone as the hydrogen acceptor, coupled with toluene or xylene as solvent, the use of higher reaction temperatures is possible and consequently the reaction time is considerably reduced furthermore, the excess of cyclohexanone can be easily separated from the reaction product by steam distillation. At least 0 25 mol of alkoxide per mol of alcohol is used however, since an excess of alkoxide has no detrimental effect 1 to 3 mols of aluminium alkoxide is recommended, particularly as water, either present in the reagents or formed during secondary reactions, will remove an equivalent quantity of the reagent. In the oxidation of steroids 50-200 mols of acetone or 10-20 mols of cyclohexanone are generally employed. 

Polymer is separated from the polymerisation slurry and slurried with acetic anhydride and sodium acetate catalyst. Acetylation of polymer end groups is carried out in a series of stirred tank reactors at temperatures up to 140°C. End-capped polymer is separated by filtration and washed at least twice, once with acetone and then with water. Polymer is made ready for extmsion compounding and other finishing steps by drying in a steam-tube drier. 

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