Intimate mixing

Determine the melting point of pure cinnamic acid (133°) and pure urea (133°). Intimately mix approximately equal weights (ca. 01 g.) of the two finely-powdered compounds and determine the melting point a considerable depression of melting point will be observed. Obtain an unknown substance from the demonstrator and, by means of a mixed melting point determination, discover whether it is identical with urea or cinnamic acid. 

A good 3ueld of 5-iodo-2-aminotoluene may be obtained by intimately mixing o-toluidine hydrochloride, iodine and calcium carbonate, and then adding water to the mixture. The liberated hydriodic acid reacts at once with the Calcium carbonate and the lij driodide of the base is not formed. 

Method 2. Intimately mix 99 g. of pure phthahc anhydride and 20 g. of urea, and place the mixture in a 1 litre long-necked, round-bottomed flask. Heat the flask in an oil bath at 130-135°, When the contents have melted, eflfervescence commences and graduaUy increases in vigour after 10-20 minutes, the mixture suddenly froths up to about three times the original volume (this is accompanied by a rise in temperature to 150-160°) and becomes almost sohd. Remove the flame from beneath the bath and allow to cool. Add about 80 ml. of water to disintegrate the sohd in the flask. Alter at the pump, wash with a httle water, and then dry at 100°. The yield of phthahmide, m.p. 233° (i.e., it is practically pure) is 86 g. If desired, the phthahmide may be recrystalhsed from 1200 ml. of methj lated spirit the first crop consists of 34 g. of m.p. 234°, but further quantities may be recovered from the mother hquor. 

It is usually preferable to oxidise the compound directly as follows. Intimately mix 0 02-0 05 g. of the eompound with 3 g. of sodium peroxide and 2 g. of anhydrous sodium carbonate in a niekel erucible. Heat the crueible and its eontents with a small flame, gently at first, afterwards more strongly until the eontents are fused, and eontinue heating for a further 10 minutes. Allow to stand, extract the contents of the crucible with water, and filter. Add exeess of eoneentrated nitrie acid to the filtrate and test with ammonium molybdate reagent as above. A yellow preeipitate indicates the presenee of phosphorus. It must be borne in mind that the above treatment 1 eonvert any arsenie present into arsenate. 

Although isotope-dilution analysis can be very accurate, a number of precautions need to be taken. Some of these are obvious ones that any analytical procedure demands. For example, analyte preparation for both spiked and unspiked sample must be as nearly identical as possible the spike also must be intimately mixed with the sample before analysis so there is no differential effect on the subsequent isotope ration measurements. The last requirement sometimes requires special chemical treatment to ensure that the spike element and the sample element are in the same chemical state before analysis. However, once procedures have been set in place, the highly sensitive isotope-dilution analysis gives excellent precision and accuracy for the estimation of several elements at the same time or just one element. 

A major example of isotope-dilution analysis lies in the procedure itself, which does not require any quantitative isolation of the elements being investigated. The relation between the abundance of the element under investigation and the spike is such that, once the spike has been intimately mixed with the sample, any losses of sample have no effect on the result (Figure 48.14). 

Furan hot-box resins are used in both ferrous and nonferrous foundries (66,67). In this process, resin and catalyst are intimately mixed with dry sand and then blown into heated metal boxes containing a cavity the shape of the desired core. In seconds, the surface of the sand mass hardens and, as soon as the core has cured sufficiently to be rigid and handleable the box is opened and the core removed. Automotive cores with exceUent dimensional accuracy and high strengths are made via this forty-year-old process. 

Magnesium fluoride is a by-product of the manufacture of metallic beryllium and uranium. The beryllium or uranium fluorides are intimately mixed with magnesium metal in magnesium fluoride-lined cmcibles. On heating, a Thermite-type reaction takes place to yield the desired metal and Mgp2 (13). Part of the magnesium fluoride produced in this reaction is then used as a lining for the cmcibles used in the process. 

Filled Resins. EiEers such as glass fibers, graphite, asbestos, or powered metals are compounded into all three types of PTEE. Compounding is achieved by intimate mixing. Coagulation of the polymer with a filler produces a filled fine powder. 

Lead and 2inc minerals are so intimately mixed in many deposits that they are mined together and then separated. Silver minerals are frequendy found in association with galena. 

Lime stabilization originated in Texas after World War II, and now it is used throughout the world. Lime is most commonly applied at a 4 wt % application or ca 11 kg/m (20 Ib/yd ) for 15 cm of compacted depth. It can be applied dry as hydrated time or granular quicklime or as a wet slurry. Distribution of the latter form is dusfless. Copious amounts (as much as 5—10%) of water are always needed in excess of the optimum moisture content of the soil. Then, a requisite for success is intimate mixing with a rotary mixer, followed by compaction to a minimum of 95% Proctor density. 

Phosgene reacts slowly with cold water to give CO2 and HCl and more quickly at higher temperatures (25). In the reaction of gaseous phosgene with water, it is difficult to get the necessary intimate mixing of the gas and water. 

Milling not only provides intimate mixing, but also eliminates variation in ribbon thickness and cmshes lumpy materials, eg, overdried soap, which might impact finished bar texture. Milling is also used for the formation of the proper bar soap crystalline phase, which plays a critical role in both the performance properties of the soap bar and the handling characteristics of the in-process soap. For example, too hot a milling temperature can create sticky soap that is difficult to process further. 

The most widely used submerged-culture oxidizer is the Brings acetator (50). It uses a bottom-driven hoUow rotor turning in a field of stationary vanes arranged in such a way that the air which is drawn in is intimately mixed with the Hquid throughout the whole bottom area of the tank (51,52). In the United States, continuous cavitator units are used widely for cider-vinegar production. 

Oxidation. Oxidized or blown castor oils are clear viscous oils that are made by the intimate mixing (blowing) of castor oil and air or oxygen at 80—130°C, with or without the use of a catalyst. The reaction is a combination of oxidation and polymerization promoted by transitionary metals like iron, copper, and manganese (60,61). The range of the properties of commercially available oils are given in Table 8. 

Thermoplastic elastomers that are hard polymer/elastomer combinations are often not truly synthesized. Instead, the two polymers that form the hard and soft phases are intimately mixed on high shear equipment. 

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