Transferring the Product

Bulk adhesives and sealants are normally supplied in containers that range in volume from 1 qt to 55-gal drums. The method used to extract the adhesive from the container should be carefully thought out. 

If a filled resin is used, it will be advantageous to first place the unopened can on a paint shaker or roller and vibrate or roll the contents for a time. If the resin is in a drum, drum rollers may be used to ensure that the components within the drum are uniformly dispersed before the drum is opened. The least aggressive method should always be used so as to obtain uniform distribution of the components with minimal addition of air into the product. 

Once the contents of the container are evenly distributed, the adhesive or sealant material can be removed. The use of pumps for transferring the adhesive or sealant has several drawbacks. Filled compounds have an abrasive action on the moving parts. This is particularly true with fillers such as silica. Compounds that polymerize easily will tend to begin their polymerization due to friction within the pump. This will gum up the moving parts and make them inoperable. Therefore, transfer is best done under some type of pressure. 

Although it may require special designs, pressure transfer does eliminate the problems that occur with gear pumping methods. Many resinous systems may be moved from their original drums by air pumps. Transfer distances should be short, and lines should be smooth and noncorrosive. In some instances, barrel warmers and heated lines may be required to reduce pressures required to transport materials. Under no circumstances should the same transfer equipment be used on different resins without complete and thorough cleaning. This will avoid the contamination of one resin system with the other. 

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A little sulphurous acid may be present. This may be removed by transferring the product to a separatory funnel, shaking gently with 5 ml. of 10 per cent, sodium hydroxide solution (the pressure should be released from time to time by inverting the funnel and turning the stopcock), followed by water. This purihca tion is unnecessary if the amylene is only to be used ibr the experiments in Section 111,11. 

Hydrogen Abstra.ction. These important reactions have been carried out using a variety of substrates. In general, the reactions involve the removal of hydrogen either direcdy as a hydrogen atom or indirectly by electron transfer followed by proton transfer. The products are derived from ground-state reactions. For example, chlorarul probably reacts with cycloheptatrienyl radicals to produce ether (50) (39). This chemistry contrasts with the ground-state reaction in which DDQ produces tropyhum quinolate in 91% yield (40). 

Wliile heat transfer processes are very useful in the energy field, there are many other industries that rely heavily on heat transfer. The production of chemicals, the cooling of electronic equipment, and food preparation (both freezing and cooking) rely heavily on a thorough knowledge of heat transfer. 

When the product ion moved with a higher kinetic energy than predicted by the stripping model, the collision apparently was more elastic— i.e., less kinetic energy of the incident ion was used for internal excitation of the products. In an ideal elastic collision with H transfer the products carry no internal energy at all. If the secondary ion moves forward and the H atom moves backwards, conservation of momentum requires that the primary ion has a velocity ... 

Glutamine also supplies an amino function to start off purine nucleotide biosynthesis. This complex little reaction is again an Sn2 reaction on PRPP, but only an amino group from the amide of glutamine is transferred. The product of the enzymic reaction is thus 5-phosphoribosylamine. 

Glass-jointed equipment is required in this step. The flask with a glass joint was used in the preceding operation oifly to avoid the necessity of transferring the product after the evaporation. 

When the reaction ends, rapidly transfer the product into an apparatus for fractional distillation at atmospheric pressure (see Fig. 20). Distil off the benzene at 80 °C, heating the flask on an electric stove with an enclosed coil. After distilling off the benzene, pour the water out of the cooler. Disconnect the receiver with the benzene and connect a new dry receiver. Perform further distillation and gather the fraction boiling at 172-174 °C. 

Break the test tube and transfer the product of roasting in small portions into a beaker containing 20 ml of a 25% hydrochloric acid solution. What gas evolves How can you explain the observed flashes of light Write the equations of the reactions. Filter off the silicon gathered on the bottom of the beaker. 

It is good to perform all the operations in platinum ware. Transfer the product into a weighed weighing bottle and weigh it. Calculate the yield in per cent. Ammonium heptafluohafnate can be prepared in a similar way. 

Fill the apparatus with chlorine and perform chlorination of the molybdenum, heating the place of the tube where the metal is with the flame of a burner to 200-300 °C. What colour do molybdenum pentachloride and tungsten hexachloride have If oxychlorides are produced together with the molybdenum(V) or tungsten(VI) chlorides, distil them off in a chlorine stream. Transfer the product into a weighed test tube with a stopper, weigh it, and hand it in to your instructor. Calculate the yield in per cent. 

Roast 2-3 g of lead carbonate at 450-500 °C in a porcelain bowl. When decomposition of the salt terminates, roast the substance at the same temperature for another two or three hours. Next transfer the product into a beaker and boil it several times with a lead acetate solution. Pour off the solution from the precipitate, filter off the latter, wash it with hot water, and dry it in a drying cabinet at... 

Diazotise 223 g. of 2-naphtliylamine-l-sulphonic acid as detailed under fi-Bromonaphthalene in Section IV,62. Prepare cuprous cyanide from 125 g. of cupric sulphate pentahydrate (Section IV,66) and dissolve it in a solution of 65 g. of potassium cyanide in 500 ml. of water contained in a 1-litre three-necked flask. Cool the potassium cuprocyanide solution in ice, stir mechanically, and add the damp cake of the diazonium compound in small portions whilst maintaining the temperature at 5-8°. Nitrogen is soon evolved and a red precipitate forms gradually. Continue the stirring for about 10 hours in the cold, heat slowly to the boiling point, add 250 g. of potassium chloride, stir, and allow to stand. Collect the orange crystals which separate by suction filtration recrystallise first from water and then from alcohol dry at 100°. The product is almost pure potassium 2-cyanonaphthalene-l-sulphonate. Transfer the product to a 2-litre round-bottomed flask, add a solution prepared from 400 ml. of concentrated sulphuric acid and 400 g. of crushed ice, and heat the mixture under reflux for 12 hours. Collect the -naphthoic acid formed (some of which sublimes from the reaction mixture) by suction filtration... 

Then add soln C in the same manner over a period of 55 mins. Stirr for 15 mins, then allow to cool to 55°. Decant the supernate from the solid product and wash by decantation 5 times with 500ml w. Transfer the product to a plastic bottle with a w wash bottle and store under w. 

Prepare copper(i) cyanide from lOOg (0.4 mol) of hydrated copper(n) sulphate following the procedure described in Section 4.2.23, p. 429, transfer the product to a 1-litre round-bottomed flask and dissolve it in a solution of 52 g of potassium cyanide in 125 ml of water (CAUTION). 

Recently a series of dialkylpyrrolidinium (Pyr+) cations have been studied in our laboratory 7-9). These cations are reduced at relatively positive potentials and could be investigated electrochemically as low concentration reactants in the presence of (C4H9)4N+ electrolytes. Using cyclic voltammetry, polarography and coulometry, it was shown that Pyr+ react by a reversible le transfer. The products are insoluble solids which deposit on the cathode and incorporate Pyr+ and mercury from the cathode. Both the cation and the metal can be regenerated by oxidation. Quantitative analysis of current-time transients, from potential step experiments, showed that the kinetics of the process involve nucleation and growth and resemble metal deposition. 

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