Organic solvent condensation

The precipitator is a jacketed vessel of 2.5 L of inner volume. The formed particles are collected in a frit at the bottom of the precipitator vessel, which consists of a metallic porous disk used to support a polymeric filter with a pore size of 0.1 pm. Afterward, the effluent from the precipitator is depressurized using a GO back-pressure valve, the organic solvent condensed after the depressurization is collected in a flash vessel, and gaseous CO2 is vented. 

C8H10N4O2. An alkaloid occurring in tea, coffee and guarana, from which it may be prepared by extraction, It is also manufactured by the methylation of theobromine and by the condensation of cyanoacetic acid with urea. Crystallizes with H2O or anhydrous from organic solvents. M.p. (anhydrous) 235"C, sublimes at 176 C. Odourless, and with a very bitter taste. Caffeine acts as a stimulant and diuretic, and is a constituent of cola drinks, tea and coffee. 

It is manufactured by heating dicyandiamide, H2N C(NH) NH CN, either alone or in the presence of ammonia or other alkalis, in various organic solvents. Melamine is an important material in the plastics industry. Condensed with melhanal and other substances it gives thermosetting resins that are remarkably stable to heat and light. U.S. production 1980 80 000 tonnes. 

MIBK is a flammable, water-white Hquid that boils at 116°C. It is sparingly soluble in water, but is miscible with common organic solvents. It forms an a2eotrope with water as shown in Table 2. Condensation of MIBK with another methyl ketone can produce ketones containing 9—15 carbons. For example, condensation with acetone produces diisobutyl ketone, and self-condensation of two MIBK molecules produces 2,6,8-trimethyl-4-nonanone [123-17-1]. Condensation with 2-ethylhexanal gives 1-tetradecanol (7-ethyl-2-methyl-4-undecanol), avaluable surfactant intermediate (58). 

Diacetone Alcohol. Diacetone alcohol (DAA) (4-hydroxy-4-methyl-2-pentanone) is a colorless, mild smelling Hquid which is completely miscible with water and most organic solvents. It is the simplest aldol condensation product of acetone, and because of its keto-alcohol functionahes it has special utility in the coatings industry where it is used to dissolve cellulose acetate to give solutions with high tolerance for water (115). 

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. 

Magnesium ethylate is used as a drying agent for organic solvents, as an intermediate for the manufacture of organomagnesium and other organic products, as catalyst in the Tishchenko (85) and other reactions (86—91), in the condensation of esters (92), in alkylation reactions, and in polymeri2ations (84,91). 

The replacement of the hydrogen of the methylo1 compound with an alkyl group renders the compound much more soluble in organic solvents and more stable. This reaction is also cataly2ed by acids and usually carried out in the presence of considerable excess alcohol to suppress the competing self-condensation reaction. After neutrali2ation of the acid catalyst, the excess alcohol may be stripped or left as a solvent for the amino resin. 

More conveniently, compound (13) was directly condensed with barbituric acid (14) in acetic acid (28) or in the presence of an acid catalyst in an organic solvent (29). The same a2o dye intermediate (13) and alloxantin give riboflavin in the presence of palladium on charcoal in alcohoHc hydrochloric acid under nitrogen. This reaction may involve the reduction of the a2o group to the (9-phenylenediamine by the alloxantin, which is dehydrogenated to alloxan (see Urea) (30). 

Ethylene oxide is a colorless gas that condenses at low temperatures into a mobile Hquid. It is miscible in all proportions with water, alcohol, ether, and most organic solvents. Its vapors are flammable and explosive. The physical properties of ethylene oxide are summarized in Tables 1—7. 

Whereas the butylated resins have enhanced solubility in organic solvents, enhanced solubility in water (which is rather limited in resins of high molecular weight) is required for some purposes and this may be achieved in a number of ways. For example, in acid condensation of urea and formaldehyde in the presence of sodium bisulphite the following reaction takes place ... 

Although waterborne systems were developed in the 1960s, the form of this chemistry that dominates the industry utilizes end-functional, high molecular weight base polymers dissolved in organic solvents. Work on solventless condensation systems continues, but has not yet become commonplace [45,47]. Solvent-borne condensation cure systems are convenient for their ease of pro-... 

Polycarbonates (PC) are another group of condensation thermoplastics used mainly for special engineering purposes. These polymers are considered polyesters of carbonic acid. They are produced by the condensation of the sodium salt of bisphenol A with phosgene in the presence of an organic solvent. Sodium chloride is precipitated, and the solvent is removed by distillation ... 

For evaporation at the boiling point either a conical flask with a short Pyrex funnel in the mouth or a round-bottomed flask inclined at an angle of about 45° may be employed in the latter the drops of liquid, etc., thrown up by the ebullition or by effervescence will be retained by striking the inside of the flask, while gas and vapour will escape freely. When organic solvents are employed the flask should be fitted with a swan-neck tube and a condenser so that the solvent is recovered. 

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