Boiling point solving problems with

Note The following problem was solved with the temperature (T) set at the normal boiling point. To solve for another temperature, simply change T to the approriate value. 

The reliability or stability of a method covers its ability to reach a solution for a wide group of problems in a general range of mixtures, such as wide or narrow boiling, and if it can solve columns across the whole spectrum of boiling point ranges. It also covers the ability of the method to solve the same column with variations in some of the specifications such as number of trays, reflux ratio, or feed conditions. 

The advent in 1952 of PTGC ° and the subsequent introduction of commercial equipment for temperature programming provided the necessary means to analyze complex mixtures that contained components of widely differing boiling points and solved some of the problems previously described in the section dealing with isothermal separations. 

With unmodified rhodium carbonyl catalyst, a high yield of dialdehyde can normally be achieved. After the reaction, the crude aldehyde is separated from the rhodium by distillation. Because of the two aldehyde groups and the high boiling point of the product, much high-boiling residue is formed too, which is difficult to handle with respect to the recovery of the rhodium. Therefore, a remarkable amount is lost. In order to solve this problem, re-immobilized catalysts were developed and tested especially with this product. At first, it was found that re-immobilized catalysts as well as TPP-modified Rh catalysts could be used, if the rhodium concentration was raised from about 30 to 80 ppm with a reaction time prolonged from 2 to 4 h. 

Process 2 - Process Description. The impurities in the raw material form azeotropes with tetrahydrofuran and ethylacetate. All the azeotropes had to be separated by a combination of counter current extraction and rectification. The aim was to recover ethylacetate and THF. The following major problems had to be solved by a solvent recovery unit 1) separate the THF/ methanol and the THF/ ethanol azeotropes, 2) dewater the THF and ethylacetate (azeotropes), 3) separate THF (Atmospheric boiling point (Tb) = 65.7°C) from ethylacetate (Tb= 77°C) and methylacetate (Tb = 57.1°C). 

The second group of polyols, which are solid at the temperature conditions of PO polymerisation lead to very serious technological problems how is it possible to efficiently react a solid polyol with a gaseous monomer (PO boiling point (bp) is 33.6 °C and the EO boiling point is 10.8 °C). This problem was solved in various ways and is discussed in detail in section 13.2.4. 

Determination of amino acid composition is, beyond doubt, the most informative method in the analysis of synthetic peptides. The preceding hydrolysis of peptide bonds must of course be complete. This can be achieved by dissolving the sample in constant boiling hydrochloric acid and heating of the solution, preferably in an evacuated and sealed ampoule, at 110°C for 16 hours. Some blocked intermediates, however, are insoluble in the ca 6 N HCl even at its boiling point. In such cases mixtures of HCl with formic acid or acetic acid can solve the problem. For the hydrolysis of polymer-bound peptides often an HCl-propionic acid mixture is applied. The presence of methionine sulfoxide in synthetic peptides deserves special consideration. On hydrolysis with HCl both methionine and its sulfoxide appear on the recordings of the amino acid analyzer, but not necessarily in the ratio they occur in the sample. The sulfoxide is partially reduced ... 

Problem concerning of removal of some (highly-boiling point) solvenk from products can be solved by synthesis of particles in the solvents with low-boiling temperature, such as CO2 solution. Silver and copper nanoparticles were synthesized in AOT reverse micelles in compressed propane and supercritical- CO2 solutions... 

In the identification of esters we are faced with problems of identifying their acid and alcoholic components. In principle, we can solve this problem in two ways—either by identifying the alcoholic component in one part of the sample and the acid in the other part, or by carrying out a hydrolysis of the ester and isolation of both reaction products, followed by their identification. The choice of method depends on the nature of the ester preliminary physical tests can help in making the proper choice (melting point, boiling point, refractive index). 

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