Purification columns

The bottoms from the solvent recovery (or a2eotropic dehydration column) are fed to the foremns column where acetic acid, some acryflc acid, and final traces of water are removed overhead. The overhead mixture is sent to an acetic acid purification column where a technical grade of acetic acid suitable for ester manufacture is recovered as a by-product. The bottoms from the acetic acid recovery column are recycled to the reflux to the foremns column. The bottoms from the foremns column are fed to the product column where the glacial acryflc acid of commerce is taken overhead. Bottoms from the product column are stripped to recover acryflc acid values and the high boilers are burned. The principal losses of acryflc acid in this process are to the aqueous raffinate and to the aqueous layer from the dehydration column and to dimeri2ation of acryflc acid to 3-acryloxypropionic acid. If necessary, the product column bottoms stripper may include provision for a short-contact-time cracker to crack this dimer back to acryflc acid (60). 

The rotating-disk contactor (RDC), developed in the Netherlands (158) in 1951, uses the shearing action of a rapidly rotating disk to interdisperse the phases (Eig. 15b). These contactors have been used widely throughout the world, particularly in the petrochemical industry for furfural [98-01-1] and SO2 extraction, propane deasphalting, sulfolane [126-33-0] extraction for separation of aromatics, and caprolactam (qv) [105-60-2] purification. Columns up to 4.27 m in diameter are in service. An extensive study (159) has provided an excellent theoretical framework for scale-up. A design manual has also been compiled (160). Detailed descriptions and design criteria for the RDC may also be found (161). 

Product Recovery. The aHyl chloride product is recovered through the use of several fractional distillation steps. Typically, the reactor effluent is cooled and conducted into an initial fractionator to separate the HCl and propylene from the chloropropenes, dichloropropanes, dichloropropenes, and heavier compounds. The unconverted propylene is recycled after removal of HCl, which can be accompHshed by adsorption in water or fractional distillation (33,37,38) depending on its intended use. The crude aHyl chloride mixture from the initial fractionator is then subjected to a lights and heavies distillation the lighter (than aHyl chloride) compounds such as 2-chloropropene, 1-chloropropene, and 2-chloropropane being the overhead product of the first column. AHyl chloride is then separated in the second purification column as an overhead product. Product purities can exceed 99.0% and commercial-grade aHyl chloride is typicaHy sold in the United States in purities about 99.5%. 

Column 1 (purification) Column 2 (purification) Column 3 (analysis) Mobile phase 1... 

A cooler-condenser, in which the reactor off-gases are cooled and most of the MEK and unreacted alcohol are condensed. Two exchangers are used but they can be modelled as one unit. Of the MEK entering the unit 84 per cent is condensed, together with 92 per cent of the alcohol. The hydrogen is noncondensable. The condensate is fed forward to the final purification column. 

Product purification column plate column, diameter 1 m2, height 20 m, 15 sieve plates, design pressure 2 bar, materials stainless steel. 

The LiClprecipitation is necessary to remove any residual heparin, which may intefere with the labeling reaction. Some vendors (e.g., Ambion and Qiagen) sell RNA purification columns that should remove heparin. We have not tested any of these yet. 

In both processes, the vents from the reactor must be carefully designed. Actually, because of the high temperature configuration, the reactor vent in this process is from the overhead of the purification column. 

Validation of the purification process and of the analytical tests used for characterization of the final protein product is especially important. The purification process must be validated to ensure that it is adequate to remove extraneous substances such as chemicals used in purification, column contaminants, endotoxin, antibiotics, residual cellular proteins, inactive protein, and viruses. Analytical tests are validated by using other analytical... 

Electrophoresis apparatus (1.5 mm x 16 cm x 14 cm) Silica DNA purification column (QIAquick, Qiagen)... 

Hydrophilic size separation columns for use with aqueous samples are very popular choices for purifying proteins and carbohydrates. Protein separation columns are available on both silica and polymeric supports. It is surprising that the best of these protein purification columns in terms of resolution and in recovery of native protein are silica-based columns. One would expect that protein release from silica would be a real problem. It certainly is in many other silica columns. These columns, however, especially the TSK family of columns, give excellent recovery of enzymatic activity. I have talked to other column manufacturers who have investigated the problem. They say that when you remove the bonded phases from these columns they appear to be identical to bonded phases from a number of other, less successful, columns designed for protein purification. All of these bonded phases are primarily diol ether polymers, very hydrophilic, but of intermediate polarity. Some modification of... 

For drug substances, assure that all starting materials, in-process reagents, stable intermediates, solvents, purification columns, and so on are correct for the process and have been properly released by the quality group for their intended use in the process. All items used... 

The considerations developed so far allows setting up the final conceptual flowsheet, as displayed in Figure 11.9. After reaction and quench the off-gas is submitted to a first separation of acrylonitrile by low-temperature cooling, at 10 °C. In the decanter the liquid splits into two phases. If the acetonitrile concentration is negligible, the organic phase containing acrylonitrile can be sent directly to the first purification column (Heads). The aqueous phase is sent to the acrylonitrile recovery. The off-gas from flash is compressed at 4.5 bar and submitted to absorption in cold water of 5 °C. In this way higher acrylonitrile recovery may be achieved (over 99.8%) with reduced water consumption. 

Figure 5 Schematic of a complete multiplexed and integrated instrumental design with eight capillaries. Stars at I, U1, and U2 represent the multiplexed freeze/ thaw valves. The T-assembly is made up of eight pieces of commercial junctions stacked together. These connect to the manifold M1, the SEC (size-exclusion chromatography) purification columns, and the reaction loops. The cross-assembly is made of eight pieces of standard crosses packed together with built-in heaters. V8 is an eight-position motorized titanium valve with a center port. S1 is a two-position motorized PEEK valve. V6 is a six-position motorized PEEK valve. (Reprinted from Ref. 33 with permission.)...

The reaction conditions are optimized to achieve essentially quantitative yields and the reactor effluent is MNB-free. The reactor product is sent to a dehydration column to remove the water of reaction followed by a purification column to produce high-quality aniline product. 

Fig. 7.2 Wild type eco purification followed by SDS-PACE. (a) Consecutive steps of eco purification. Column 1, molecular weight marker from the bottom 3, 5.6, 14.8, 20.1, 29.3, 44.7 kDa column 2, pre-induction column 3, periplasmic fraction column 4, supernatant following acidification column 5, insoluble pellet following acidification step column 6, molecular weight marker column 7, neutra-...

The bottoms from the solvent recovery (or azeotropic dehydration column) are fed to the foreruns column where acetic acid, some acrylic acid, and final traces of water are removed overhead The overhead mixture is sent to an acetic acid purification column where a technical grade of acetic acid suitable for ester manufacture is recovered as a by-product. The bottoms from the acetic acid recovery column are recycled to the reflux to the foreruns column. 

Purification column chromatography on silica gel, eluting with 15-30% ethyl acetate/hexanes. Recrystallization from hot acetonitrile. ... 

Form Supplied in clear, colorless oil not commercially available. Analysis of Reagent Purity H NMR Elemental Analysis. Purification column chromatography (silica, CHCls/MeOH 9 1 then CHCl3/i-PrNH2 20 1) followed by bulb-to-bulb distillation (290 °C bath temperature, 0.8 mmHg). 

After the condensed crude methanol is recovered in the high-pressure separator, it is sent to a methanol purification column. Typically, methanol purification requires two columns, one to remove the light ends (mainly by-products generated in the methanol synthesis reactor such as dimethyl ether and dissolved gases) and another to separate methanol and water and any other by-products with a lower volatility than methanol. Specification-grade methanol (greater than 99.85 wl% methanol) is recovered as the overhead product of the heavy ends column and sent to storage. 

---