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Azeotroping agents

Processes to produce boric acid esters are based on the azeotropic removal of water from a mixture of the appropriate alcohol, phenol, or glycol, and boric acid. A suitable hydrocarbon azeotroping agent is used to help remove the water. The water is removed continuously by using a condenser that allows continuous return of the solvent to the reaction vessel. Eor some borate esters, such as the glycol borates, distillation can result in decomposition. [Pg.215]

Acid Manufacture. Relatively small mostly leakage plus drainings from air pollution abatement scrubbers. Also included are a) acid waters, neutralized with lime or soda ash b) sometimes azeotroping agents such as n-propyl acetate c) sometimes heavy metals from equipment corrosion and d) nitrobodies from acid recovery... [Pg.797]

Aliphatic and aromatic aldehydes condense with aliphatic and aromatic primary amines to form JV-substituted imines. The reaction is catalyzed by acids and is generally carried out by refluxing the amine and the carbonyl compound with an azeotroping agent in order to separate the water formed. The aliphatic imines (C5-C10) are obtained in good yield but are unstable and must be used directly after their distillation [2b], Tertiary aliphatic and aromatic aldehydes at room temperature react readily and nearly quantitatively with amines to give the imines without the aid of catalysts [la]. Primary aliphatic aldehydes tend to give polymeric materials with amines as a result of the ease of their aldol condensation [3]. The use of low temperatures and potassium hydroxide favors the formation of the imine product [4a, b]. Secondary aliphatic aldehydes readily form imines with amines with little or no side reactions [5]. [Pg.383]

A 100-ml reactor was charged with biphenol (2.0 mmol), 4,4 -difluorodiphenylsul-fone (1.66 mmol), K2C03 (6 mmol), 7 ml DMSO, and 5 ml toluene as an azeotroping agent and the mixture refluxed 4 hours while the remaining toluene was distilled off at 160°C. Thereafter the reaction mixture remained at this temperature for an additional hour and then cooled and the product isolated. [Pg.267]

Recovery of naturally occurring esters is accomplished by steam distillation, extraction, pressing, or by a combination of these processes. Synthetic esters are generally prepared by reaction of an alcohol with an organic acid in the presence of a catalyst such as sulfuric acid,y>-toluenesulfonic acid, or methanesulfonic acid. Ion-exchange resins of the sulfonic acid type can also be used, and an azeotroping agent such as benzene, toluene, or cyclohexane... [Pg.390]

The tetramethylammonium siloxanolate catalyst was prepared similarly by charging tetramethylammonium hydroxide, D4, and an azeotropic agent to the flask and heating the reaction at 80 °C for 24 h. The lower reaction temperature was necessary to avoid decomposition of the ammonium catalyst. Under most conditions, this procedure produces an active catalyst that is not completely homogeneous. Although not precisely defined, some carbonate is known to be present in addition to the siloxanolate. [Pg.147]

Addition of an azeotroping agent such as WD-propanol or n-butanol,... [Pg.133]

As slated above, a separation by distillation involves differing volatilities of the components to be separated. If the volatility difference is so small diet an adequate separation cannot be made, it may be possible to increase the volatility difference by the addition of an extraneous material that can be separated later this process is known as extractive distillation if the added material is relatively nonvolatile and leaves the column with die residue. If the added material forms an azeotrope with one or mote of the components df the mixture and in so doing enhances the separability of the original mixture, azeotropic distillation results. In this last-namad mode, the extraneous material, or azeotropic agent, may lenve the column in the distillate (low-boiling azeotrope) or in the residue (high-boiling azeotrope). [Pg.229]

In azeotropic distillation, the third component forms an azeotrope with the system that becomes either the top or bottom product. The azeotrope is then separated into the agent and component. Sometimes such separation must be done using another process such as liquid extraction. Some typical systems (the azeotroping agent in parentheses) are acetic acid-water (butyl acetate), and ethanol-water (benzene). [Pg.292]

It has been pointed out that this system differs from extractive distillation chiefly in the behavior of the agent. For example, consider the coiiflhuous dehydration of ethyl alcohol by the use of benzene as the azeotropic agent, as shown in Fig. 10-12. Tower 1 serves to remove the water from the alcohol, and tower 2 serves to recover the alcohol and benzene. Essentially anhydrous alcohol is produced as bottoms in tower 1, and sufficient plates are used above the feed plate to produce an overhead vapor that will give two liquid layers on condensation. The benzene-alcohol layer is used as reflux for tower 1, and the water layer containing small amounts of alcohol and benzene is stripped to recover these constituents. In such an operation, the agent, benzene, must vary from essentially zero in the still to a relatively high concentration in the tower. Thus there is a wide variation in the solvent concentration in the tower, and some of the approximations made for extractive distillation would lead to serious errors. [Pg.312]

Since this forward reaction is slow, a catalyst is usually employed. This allows the attainment of equilibrium in a reasonable amount of time. Removal of the product of reaction, in this case water, by azeotroping agents has been employed as well. The reacting alcohol may also function as... [Pg.79]


See other pages where Azeotroping agents is mentioned: [Pg.1078]    [Pg.67]    [Pg.282]    [Pg.457]    [Pg.108]    [Pg.214]    [Pg.1306]    [Pg.336]    [Pg.40]    [Pg.208]    [Pg.308]    [Pg.214]    [Pg.74]    [Pg.14]    [Pg.59]    [Pg.81]    [Pg.67]    [Pg.1129]    [Pg.414]    [Pg.1515]    [Pg.350]    [Pg.54]    [Pg.67]    [Pg.1512]    [Pg.340]    [Pg.1310]    [Pg.369]    [Pg.40]    [Pg.229]    [Pg.2]    [Pg.292]    [Pg.744]    [Pg.313]    [Pg.321]    [Pg.80]   
See also in sourсe #XX -- [ Pg.744 ]




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