Time-filtering

Amino-4 -methylthiazole slowly decomposes on storage to a red viscous mass. It can be stored as the nitrate, which is readily deposited as pink crystals when dilute nitric acid is added to a cold ethanolic solution of the thiazole. The nitrate can be recrystallised from ethanol, although a faint pink colour persists. Alternatively, water can be added dropwise to a boiling suspension of the nitrate in acetone until the solution is just clear charcoal is now added and the solution, when boiled for a short time, filtered and cooled, deposits the colourless crystalline nitrate, m.p. 192-194° (immersed at 185°). The thiazole can be regenerated by decomposing the nitrate with aqueous sodium hydroxide, and extracting the free base with ether as before. 

Place a mixture of 53 g. of A.R. lactic acid (85-88 per cent, acid), 75 g. (85-5 ml.) of commercial anhydrous isopropyl alcohol, 300 ml. of benzene and 20 g. of Zeo-Karb 225/H (1) in a 700 ml. bolt-head flask, equipped with an automatic water separator (e.g., a large modified Dean and Stark apparatus with a stopcock at the lower end, see Fig. Ill, 126, 1) carrying an efficient reflux condenser at its upper end, and a mercury-sealed stirrer (alternatively, the hquid-sealed stirrer shown in Fig. 11,7,11, c. may be used). Reflux the mixture, with stirring, on a steam bath for 5 hours or until water no longer collects in appreciable amount in the water separator run off the water from time to time. Filter off the resin at the pump and wash it with two 25 ml. portions of benzene. Shake the combined filtrate and washings with about 5 g. of precipit-ated calcium... 

It is possible to place a soil sample in an Erlenmeyer flask or other suitable container, add the desired extractant, stopper and shake for a specified period of time, filter, and analyze the extract for the analyte of interest. For an example of this type of extraction, see Procedure 12.1.4 The extract obtained from the simple extraction of 10 g of soil with water using a magnetic stirrer is shown in the right-hand flask in Figure 12.4 (see also Section 12.2.2). 

Design and operational variables Chemicals Coagulation aids, media size, sludge recirculation Energy input, mass transport Residence time filter length and media diameter... 

Benzhy dr azide.1—24 g. (0-15 mole) of ethyl benzoate (p. 141) are heated for six hours under a small reflux condenser on the water bath with 9 g. of hydrazine hydrate.2 The solid crystalline cake which is formed on cooling is, after some time, filtered as dry as possible at the pump and washed with a little ice-cold methyl alcohol. If the yield is too small the filtrate is concentrated and heated again. 

The photocatalytic decomposition products of methyl orange were separated by RP-HPLC and identified by MS, MS/MS techniques. Methyl orange was irradiated in the presence of Ti02 dispersions. Samples were taken after various incubation times, filtered... 

Batch slurry reactions were carried out in liquid phase in a stirred glass vessel with condenser. Catalyst was added to a preheated solution containing aromatic reactant (35ml, Aldrich) and iso-butyric anhydride (16ml, Aldrich) in a 3 1 molar ratio. Samples of the reaction mixture were removed from the reaction mixture after various reaction times, filtered and analysed by gas chromatography (column DB-5, 30m, He carrier gas, FID detector) to determine reaction progress. Product identification was made by comparison with appropriate reference materials. 

When the basket apparatus is used, the sample is placed in the dry basket the basket fitted to the coupling disk and lowered to the position specified, and rotation is started immediately. When the paddle apparatus is used, the sample is allowed to sink to the bottom of the vessel, and rotation of the paddle started immediately at the speed specified. If use of the sinker is required, the sample is placed in the sinker and allowed to sink to the bottom of the vessel. The samples are collected at the appropriate time, filtered by a suitable method, and the filtrate used as the sample solution. The drug substance(s) in the sample solution is assayed, and the quantity dissolved at the specified time is expressed as a percentage of the labeled amount. 

For the recoveiy of thallium from the flue dust of pyrite burners, the dust is boiled with H2O, allowed to stand some time, filtered, and HC1 added to die filtrate, whereupon crude thallous chloride is precipitated. This is purified by further treatment, and thallium metal obtained (1) by electrolysis of the sulfate solution or (2) by fusion of the chloride widi sodium cyanide and carbonate. 

Logic modules are used to monitor the counting rate of single detectors and the relative times at which radiation is detected. A fast signal derived from the detector itself, the preamplifier, or from a timing-filter amplifier is sent to a discriminator. 

In this study the numerical simulations were performed with a 3-D mechanistic global Cologne Model of the Middle Atmosphere (COMMA) based on the primitive equations expressed in spherical coordinates for the horizontal and log-pressure coordinates in the vertical direction. The model equations are solved on the basis of an explicit numerical scheme (leapfrog) with a fixed time step of 450 sec. To avoid separate evolution at even and odd time steps, a Robert time filter is used. 

After cooling the reaction mixture in an ice-bath, the inorganic salts were removed by filtration and washed with acetone. The combined filtrates were concentrated in vacuo. The residual syrup was diluted with saturated brine and extracted with three portions of diethyl ether. The gathered extracts were dried over anhydrous magnesium sulfate, clarified with charcoal and treated with ethereal hydrogen chloride until precipitation was complete. The solid was slurried in diethyl ether and decanted several times, filtered and air-dried to give 3.8 g (86%) of tan 4-(2-di-n-propylaminoethyl)-7-(l-phenyl-lH-tetrazol-5-yloxy)-2(3H)-indolone hydrochloride. Recrystallization from 200 cc of hot acetonitrile gave 2.6 g (59%) of microcrystalline product, m.p. 245°C. 

CHAPTER 21 THE PREPARATION OF NITRO PARAFFINS AND THEIR DERIVATIVES potassium salt will begin to precipitate. After the heating process, remove the heat source, and allow the reaction mixtureto cool to room temperature. Then, pi ace the reaction mixture into an ice water bath for 30 to 50 minutes. After which time, filter-off the potassium salt, and then vacuum dry or air-dry the product. The result will be about 12gramsof relatively pure potassium nitroform. 

At the end of the reaction time, filter the soln through a fritted funnel directly into cold, stirred Et20 or MTBE (200 mL). More complete precipitation of the peptide may be obtained if the Et20 is chilled in dry ice/EtOH. Wash the resin with three small portions of cold TFA. Add dry Py (1.0 mL) dropwise to the cold, stirred Et20 suspension to complete peptide precipitation. Collect the peptide on a fine-pore fritted glass funnel, wash with cold EtjO (3 X), and air-dry. Purify the crude peptide by an acceptable procedure. 

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