Evaporators Electrically heated

Concentrate each of the two solutions (or eluates) to about 20 ml, by distilling off the greater part of the benzene, the distilling-flask being immersed in the boiling water-bath. Then pour the concentrated solution into an evaporating-basin, and evaporate the remaining benzene (preferably in a fume-cupboard) in the absence of free flames, i.e., on an electrically heated water-bath, or on a steam-bath directly connected to a steam-pipe. Wash the dry residue from the first eluate with petrol and then dry it in a desiccator pure o-nitroaniline, m.p. 72°, is obtained. Wash the second residue similarly with a small quantity of benzene and dry pure />--nitroaniline, m.p. 148" , is obtained. Record the yield and m.p. of each component. 

In a 500-ml. round-bottomed flask fitted with a reflux condenser are placed 16.2 g. (0.08 mole) of dry a-naphthylthiourea (Note 1) and 180 ml. of redistilled chlorobenzene. The flask is heated at the reflux temperature by means of an electric heating mantle. Evolution of ammonia begins almost at once, and all of the solid dissolves after 30-45 minutes. The solution is maintained at reflux for 8 hours (Note 2) and then evaporated on a steam bath at water-pump pressure to remove all of the chlorobenzene. The residue crystallizes on cooling and is extracted with four 30-ml. portions of boUing hexane (Note 3). Removal of solvent from the combined hexane extracts affords pale yellow crystals of naphthyl isothiocyanate, m.p. 58-59°. The yield is 12.7-13.0 g. (86-88%). Recrystallization from hexane (9 ml. of hexane for 1 g. of solute) gives colorless needles, melting point unchanged (Note 4). 

Cold store evaporators for use below + 2°C must also have some means of defrosting the coil. If this is to be by electric heat, the elements will be inbuilt. 

Arc Plasma Method The principle of NPs synthesis in this method is based on evaporation by heating and condensation by cooling. The bulk metal is evaporated by heating with electrical resistance, electron beam, or high-frequency magnetics, and subsequently the vapor of metal atoms is condensed on a substrate as a sohd film or particles. In the AP method, electrical charge filled in an external capacitor... 

Most of these studies, mainly in the period 1955 to 1970, have been concerned with cathodic hydrogen evolution. Different parameters characterizing the bulk properties of each metal have been adduced, including physical parameters such as electron work funchon, electrical conductivity, hardness, compressibility, temperature of evaporation, and heat of evaporation, and chemical parameters such as the affinity to hydrogen or oxygen. 

Rotary vacuum evaporator, 40 °C bath temperature Dry-block bath, electrically heated, temperature 75 °C Mechanical shaker (universal shaker)... 

SPE cartridge column Mega Bond Elut Cig, lO-g/60-mL (Varian). The SPE cartridge column is rinsed with 100 mL of methanol and 100 mL of distilled water Rotary vacuum evaporator, 40 °C bath temperature Water-bath, electrically heated, temperature 80 °C Mechanical shaker (universal shaker)... 

The production of an homogeneous atomic vapour from a sample is achieved by aspirating a solution into a flame or evaporating small volumes in an electrically heated tube furnace or from the surface of a carbon rod. In all cases, the thermal energy supplied must (a) evaporate the solvent and (b) dissociate the remaining solids into their constituent atoms without causing appreciable ionization. 

Highly flammable, should be heated or evaporated on steam or electrically heated water baths only (preferably in a nitrogen atmosphere). 

Hexanoic acid. Into a 2-litre three-necked flask, fitted with a separatory funnel, a mechanical stirrer and a reflux condenser, place a hot solution of 200 g of potassium hydroxide in 200 ml of water. Stir the solution and add slowly 200 g (0.925 mol) of diethyl butylmalonate. A vigorous reaction occurs and the solution refluxes. When all the ester has been added, boil the solution gently for 2-3 hours, i.e. until hydrolysis is complete a test portion should dissolve completely in water. Dilute with 200 ml of water and distil off 200 ml of liquid in order to ensure the complete removal of the alcohol formed in the hydrolysis (2). To the cold residue in the flask add a cold solution of 320 g (174 ml) of concentrated sulphuric acid in 450 ml of water add the acid slowly with stirring in order to prevent excessive foaming. The solution becomes hot. Reflux the mixture for 3-4 hours and allow to cool. Separate the upper layer of the organic acid and extract the aqueous portion with four 150 ml portions of ether (3). Combine the acid layer with the ether extracts, wash it with 25 ml of water and dry with anhydrous sodium sulphate. Distil off the ether (rotary evaporator), transfer the residue to a flask fitted with a short fractionating column (the latter should be well lagged and, preferably, electrically heated) and distil the product from an air bath. Collect the hexanoic acid at 200-206 °C. The yield is 80 g (75%). Record the i.r. spectrum and compare it with that shown in Fig. 3.31. 

The most widely used vacuum deposition techniques are evaporation and sputtering, often employed for smaller substrates. In the evaporation process, heating the metal by an electron beam or by direct resistance produces the vapours. The system is operated at a very high vacuum (between 10-5 and 10 6 Torr) to allow a free path for the evaporant to reach the substrate. The rate of metal deposition by evaporation processes varies from 100 to 250,000 A min h These processes can be operated on a batch or a continuous scale. On the other hand, in the case of the sputtering technique, the reaction chamber is first evacuated to a pressure of about 10-5 Torr and then back-filled with an inert gas up to a pressure of 100 mTorr. A strong electric field in the chamber renders ionisation of the inert gas. These inert gas ions... 

A combined evaporator and methanol reformer was developed by Park et al. [124] to power a 5 W fuel cell. However, the device was still electrically heated by heating cartridges. Both the evaporator and the reformer channels, which were identical in size, were prepared on metal sheets 200 pm thick by wet chemical etching. The channel dimensions were length 33 mm, width 500 pm and depth 200 pm. Therefore, the channels were completely etched through the sheets and the channel depth could be varied by introducing several of these sheets into the reactor. The flow distribution between the 20 channels of the device was performed by triangular inlet and outlet fields. Both devices had outer dimensions of 70 mm x 40 mm x 30 mm. 

Thermal vacuum evaporation. This method is used for evaporation and the subsequent deposition of various metals. Rather volatile metals such as Ag, Au, Cu, and Pd can be evaporated from heated containers. Evaporation of less volatile metals, in particular, Ti or Mo, occurs by electrical heating of metal filaments or bands [32]. In certain conditions chemical active gases, such as oxygen, sulfur vapors, and others, introduced in evaporation zone react with metal atoms giving semiconductor compounds (for example, oxides, sulfides). 

Each of the evaporators is electrically heated by use of a high current, some 100 A, which is fed at a low alternating potential of approximately 10 V. This is achieved by using high-current transformers with a thyristor-controlled primary current. Layer thickness monitors, positioned over the width of the web at the same dis-... 

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