Water under vacuum

Lithium Iodide. Lithium iodide [10377-51 -2/, Lil, is the most difficult lithium halide to prepare and has few appHcations. Aqueous solutions of the salt can be prepared by carehil neutralization of hydroiodic acid with lithium carbonate or lithium hydroxide. Concentration of the aqueous solution leads successively to the trihydrate [7790-22-9] dihydrate [17023-25-5] and monohydrate [17023-24 ] which melt congmendy at 75, 79, and 130°C, respectively. The anhydrous salt can be obtained by carehil removal of water under vacuum, but because of the strong tendency to oxidize and eliminate iodine which occurs on heating the salt ia air, it is often prepared from reactions of lithium metal or lithium hydride with iodine ia organic solvents. The salt is extremely soluble ia water (62.6 wt % at 25°C) (59) and the solutions have extremely low vapor pressures (60). Lithium iodide is used as an electrolyte ia selected lithium battery appHcations, where it is formed in situ from reaction of lithium metal with iodine. It can also be a component of low melting molten salts and as a catalyst ia aldol condensations. 

Juice-Based Flavors. Fmit juices are concentrated for use ia carbonated beverage flavors. The final juice is concentrated between four to six times its initial strength by removing the water under vacuum it is then pasteurized. Orange, grapefmit, lemon, grape, and apple are the most common fmit juices used ia carbonated beverages. 

In practice, the taffy process is generally employed for only medium molecular-weight resins (1) (n = 1-4). The polymerization reaction results in a highly viscous product (emulsion of water and resin) and the condensation reaction becomes dependent on agitation. At the completion of the reaction, the heterogeneous mixture consists of an alkaline brine solution and a water—resin emulsion and recovery of the product is accompHshed by separation of phases, washing of the taffy resin with water, and removal of water under vacuum. 

Ether carboxylates with two alkyl chains are produced by reacting nonionics with dichloroaceticacid and a 50% solution of NaOH in water under vacuum at temperatures between 115°C and 120°C [28]. Compounds of the type... 

Our method is demonstrated with experiments on a Bentheimer sandstone sample. The sample was prepared to be cylindrically shaped with a diameter of 2.5 cm and a length of 2.0 cm. The sample was fully saturated with de-ionized water under vacuum. We performed the CPMG imaging experiment described in the previous section to measure the magnetization intensity at 50 echoes spaced by 4.6 ms for each of 32 x 16 x 16 voxels within the field of view of 3.0 cm x 3.0 cm x 3.0 cm. The corresponding voxel size is 0.938 mm x 1.88 mm x 1.88 mm. We used 1 s of repetition time (TR) and the total imaging time was 4.3 min. 

Following variant II, after treating by the modifier, the solid phase was separated by filtration and additionally washed off with 0.2 liters of water under vacuum of the water-jet pump. Further, as in variant I, one part of the product was dried at 105°C for two hours (product C), while the other was dried at 20°C until a sample mass became constant (product D). The products were investigated by the powder X-ray phase analysis (PXRD) using nickel-filtered CoKa radiation. 

The sorbitol solution produced from hydrogenation is purified in two steps [4]. The first involves passing the solution through an ion-exchange resin bed to remove gluconate and other ions. In the second step, the solution is treated with activated carbon to remove trace organic impurities. The commercial 70% sorbitol solution is obtained by evaporation of the water under vacuum. The solid is prepared by dehydration until a water-free melt is obtained which is cooled and seeded. The crystals are removed continuously from the surface (melt crystallization). The solid is sold as flakes, granules, pellet, and powder forms in a variety of particle size distributions. 

The original parfait method rested on the use of vacuum distillation—lyophilization to concentrate the poorly volatile species in water. It might be expected that the removal of water under vacuum should be simple and straightforward. Vacuum distillation and lyophilization do indeed recover the poorly volatile contaminants from unfractionated surface waters. However, the compounds are often obtained in an intractable, insoluble form. These intractable precipitates are believed to form when bicarbonate dissociates under vacuum to form metal carbonate precipitates that trap organic polymers and lipids (4, 5). The parfait method prevents the formation of these precipitates by removing metal ions on an acidic cation-exchange bed. 

Figure 18.4 Vapor pressure of water under vacuum.

Summary DITN can be prepared by reacting the nitrate salt of diisoproplyamine with 99% nitric acid. This nitrate salt is simply prepared by neutralizing the amine with 70% nitric acid, followed by evaporation of the water under vacuum. The nitrate is then directly nitrated with 99% nitric acid, and the product is then collected by low temperature precipitation, followed by filtration. Purification is accomplished by precipitation from a water solution at low temperature. Commercial Industrial note Part or parts of this laboratory process may be protected by international, and/or commercial/industrial processes. Before using this process to legally manufacture the mentioned explosive, with intent to sell, consult any protected commercial or industrial processes related to, similar to, or additional to, the process discussed in this procedure. This process may be used to legally prepare the mentioned explosive for laboratory, educational, or research purposes. 

Procedure Prepare a sol ution by adding 21 grams of 2-methyl-2-ami no-1,3-propanediol, 30 grams of nitroform, and 17 milliliters of 37% formaldehyde sol ution into 70 milliliters of distilled water. After preparing the sol ution, place the sol ution into an ice bath, and chill to 0 Celsius for 3 hours with rapid stirring. After 3 hours, pi ace the mixture into a rotary evaporator or vacuum distillation apparatus, and remove the water under vacuum until no more water passes into the receiver flask. 

I nto a suitable flask, add 6 grams of the product obtained in step 3, and then add 360 milliliters of 35 - 38% hydrochloric add, followed by 360 mill inters of water. Thereafter, reflux the mixture for 18 hours at about 100 Celsius. After the 18 hour refluxing period, remove the heat source, and allow the reaction mixtureto cool to room temperature. Then place the readion mixture into a rotary evaporator, and remove the water under vacuum. Afterwards, mix the residue remaining with 600 milliliters of methanol, and stir the mixture for 10 minutes Thereafter, filter-off the insolublesolid, wash with 300 milliliters of methanol, and then vacuum dry or air-dry these solids. After which, dissolve the dry solids into a minimum amount of cold water, and then filter-off any insoluble materials. Thereafter, mix 600 milliliters of acetone with the water mixtureto preci pitate the desi red produd. Then f i Iter-off the pred pitated produd, and then vacuum dry or ai r-dry. The result wi 11 be about 4 grams of the dry produd. 

For these exchange reactions, the catalyst (previously prereduced with hydrogen or borohydride, if required) is sealed in a preconstricted ampoule with the organic compound and isotopic water under vacuum (10 2 Torr). The tubes are shaken or stood at the required temperature, and after the reaction is completed the products are analyzed by infrared, vapor phase chromatography, NMR or mass spectrometry (if deuteration), or counted (tritiation). With some compounds, the material to be labeled may be refluxed with isotopic water in the presence of catalyst instead of using sealed tube procedures.76 Solvents such as acetic acid and ethanol have also been used 77-80 however, unless the solvent is fully labeled prior to exchange, the theoretical percentage of isotope incorporation at equilibrium under these conditions can be lowered by loss of isotope to the solvent. 

If desired, aqueous solution in a Dry Ice-acetone bath and removing the water under vacuum at —20°. 

The XeOs solutions may be concentrated by distilling away the water under vacuum at room temperature. This may be done either on a vacuum line or over a desiccant in a vacumn desiccator. Solutions 2 M in XeOs niay easily be prepared in this way, but extreme care must be taken not to reach dryness (vide infra). 

The equilibrium (4.1) is shifted right, towards the formation of potassium glycerolate, by distillation of the resulting water under vacuum, at 100-130 °C. A solution of potassium glycerolate in glycerol is formed. 

Approximately 5-g samples of dry ground straw (with known moisture content) were transferred to 250-ml Erlenmeyer flasks containing 160 ml of distilled water, 0.5 ml of acetic acid, and 1.5 g of sodium chlorite. The samples were heated for 60 min in a water bath at 70-80 °C with agitation every 10 min. Then, 0.5 ml of acetic acid and 1.5 g of sodium chlorite were added. This addition was repeated at 60-min intervals for 4 h reaction time. After 4 h, the Erlenmeyer flask was put in an ice bath and cooled to 10 °C. The samples were subsequently filtered in cmcibles of porosity 2. The residue was washed with 1.6 1 of hot distilled water under vacuum. The samples were finally washed with acetone and dried at room temperature [13, 14],... 

In a reaction vessel charge at 25°C, 44.4 parts by mass of water, add 30% NaOH solution to pH 11.2 to 12.0, followed by 15.5 parts of 91% paraformaldehyde prills, 34.4 parts of melamine powder, 2.8 parts of caprolactam, and 2.5 parts of iV,iV -dimethylformamide while maintaining the temperature at 25° C heat in 40 min to 92 to 95°C. When the temperature reaches 80°C, adjust the pH with 30% NaOH solution, if necessary, to pH 9.9. At 93°C, cool to 90°C and maintain the temperature there. Adjust pH to 9.55 to 9.65 with formic acid. Hold the pH at this value while checking, adjusting, and recording the pH value every 10 min. Check for the turbidity point at 10-min intervals until the turbidity point is reached. At this time bring pH up to 9.95 to 10.05. Check, adjust, and record the pH every 10 min. Start distilling water under vacuum to a solid of 53 to 55%. Check the water tolerance at 10-min intervals until it is 170 to 180%. Then apply full vacuum and cool the resin to 30 to 35°C. 

A very useful technique for preparing a mixture of a biochemical substance and alkali halide is to freeze rapidly a solution of the mixture and remove the water under vacuum (lyophilization). Although this method is not used in many organic and spectroscopic laboratories because of the need for special apparatus and the length of time required for sample preparation, it is frequently used to advantage in biochemistry laboratories, most of which own lyophilization equipment. 

The attack tank is cooled by circulating the slurry through a low-level flash cooler, in which the reaction slurry is cooled by evaporation of water under vacuum. Circulating power requirements are kept to a minimum by using an axial-flow circulation pump and by the low elevation of the flash cooler above the attack tank. The temperature in the attack tank is controlled by varying the vacuum applied to the flash cooler. 

Figure 4A.44 Synthesis of APG by acid-catalyzed acetalization of glucose in molar excess of fatty alcohol and removal of water under vacuum at 100°-120°C...

In commercial practice, the taffy method is used to prepare lower MW solid resins, ie, those with maximum EEW values of about 1000 (type 4 ). Upon completion of the polymerization, the mixture consists of an alkaline brine solution and a water-resin emulsion. The product is recovered by separating the phases, washing the taffy resin with water, and removing the water under vacuum. One disadvantage of the taffy process is the formation of insoluble polymers, which create handling and disposal problems. Only a few epoxy producers currently manufacture SERs using the taffy process. A detailed description of a taffy procedure follows (24). 

Fruit and berry juices are widely used as flavor bases for soft drinks, and most of these are concentrated by the removal of water under vacuum to give a commercial product, which is between four and six times stronger than the original juice. The flavor value of these concentrates depends not only on the degree of concentration but on the precise processing conditions used in their manufacture. From an application point of view, fruit products may be offered in sealed containers that have been pasteurized, in which case the whole contents must be used once the container has been opened, or they may be in multidose containers the contents of which contain a permitted preservative, usually sodium benzoate. All fruit-based flavorings are best stored under refrigeration or in a cold store. Fruit essences also may be... 

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