Acidic resins

Esters. Most acryhc acid is used in the form of its methyl, ethyl, and butyl esters. Specialty monomeric esters with a hydroxyl, amino, or other functional group are used to provide adhesion, latent cross-linking capabihty, or different solubihty characteristics. The principal routes to esters are direct esterification with alcohols in the presence of a strong acid catalyst such as sulfuric acid, a soluble sulfonic acid, or sulfonic acid resins addition to alkylene oxides to give hydroxyalkyl acryhc esters and addition to the double bond of olefins in the presence of strong acid catalyst (19,20) to give ethyl or secondary alkyl acrylates. 

The synthesis of 2,4-dihydroxyacetophenone [89-84-9] (21) by acylation reactions of resorcinol has been extensively studied. The reaction is performed using acetic anhydride (104), acetyl chloride (105), or acetic acid (106). The esterification of resorcinol by acetic anhydride followed by the isomerization of the diacetate intermediate has also been described in the presence of zinc chloride (107). Alkylation of resorcinol can be carried out using ethers (108), olefins (109), or alcohols (110). The catalysts which are generally used include sulfuric acid, phosphoric and polyphosphoric acids, acidic resins, or aluminum and iron derivatives. 2-Chlororesorcinol [6201-65-1] (22) is obtained by a sulfonation—chloration—desulfonation technique (111). 1,2,4-Trihydroxybenzene [533-73-3] (23) is obtained by hydroxylation of resorcinol using hydrogen peroxide (112) or peracids (113). 

Fig. 2. Total capacity vs cross-linkage for polystyreae sulfonic acid resin in the form where A and B correspond respectively to dry and wet weight capacity in meq/g of resin, and C represents wet volume capacity in meq/mL of wet setded resin.

The esterification of -butyl alcohol and oleic acid with a phenol—formaldehydesulfonic acid resin (similar to amberHte IR-100) is essentially second order after an initial slow period (52). The velocity constant is directiy proportional to the surface area of the catalyst per unit weight of reactants. 

Dowex 50W-X8, MeOH, 20°. Dowex 50W-X8 is a carboxylic acid resin,... 

Weakly acidic cation-exchange resins have carboxylic groups (COOH) as the exchange sites. When operated on the hydrogen cycle, the weakly acidic resins are capable of removing only those cations equivalent to the amount of alkalinity present in the water, and most efficiently the hardness (calcium and magnesium) associated with alkalinity, according to these reactions ... 

Weakly acidic resins are used primarily for softening and dealkalization, frequently in conjunction with a strongly acidic polishing resin. Systems which use both resins profit from the regeneration economy of the weakly acidic resin and produce treated water of quality comparable to that available with a strongly acidic resin. 

Resins currently available exhibit a range of selectivity s and thus have broad application. As an example, for a strong acid resin, the relative preference for divalent calcium ions (Ca ) over divalent copper ions (Cu ) is approximately 1.5... 

Strong acid resins are so named because their chemical behavior is similar to that of a strong acid. The resins are highly ionized in both the acid (R-SOjH) and salt (R-SOjNa) form. They can convert a metal salt to the corresponding acid by the reaction ... 

Like strong acid resins, strong base resins are highly ionized and can be used over the entire pH range. These resins are used in the hydroxide (OH) form for water deionization. They will react with anions in solution and can convert an acid solution to pure water ... 

Weak base resins are like weak acid resins, in that the degree of ionization is strongly influenced by pH. Consequently, weak base resins exhibit minimum exchange capacity above a pH of 7.0. These resins merely sorb strong acids they caimot split salts. 

In an ion exchange wastewater deionization unit, the wastewater would pass first through a bed of strong acid resin. Replacement of the metal cations (Ni. Cu ) With hydrogen ions would lower the solution pH. The anions (S04. Cl ) can then be removed with a weak base resin because the entering wastewater will normally be acidic and weak base resins sorb acids. Weak base resins are preferred over strong base resins because they require less regenerant chemical. A reaction between the resin in the free base form and HCl would proceed as follows ... 

The dealkalization process removes the temporary hardness in water. This uses an acid resin bed for regeneration—in this case sulfuric acid (H2SO4). 

Catalysis by an Acidic Resin (5).- The resin (Dowex-50,200-400 mesh or comparable sulfonated polystyrene) is prepared for use by suspending it in dilute sulfuric acid, followed by many washings with water (and decantation of the wash), and air drying for several days. 

Harz-reserve,/. (Calico) resin resist. -r3hre,/. resin duct, -saft, m. resinous j uice. -aalbe, /. (Pharm.) rosin cerate, -salz, n. resinate. harzsauer, a. of or combined with a resinic acid, resinate of. 

Harz-saure, /. resin acid, resinic acid, -aeife, /. resin soap rosin soap, -sikkativ, n. rosin drier, -spiritus, m. rosin spirit, -spur, /. trace of resin or rosin, -stippe, /. (Paper) rosin speck, rosin spot, -stoff, m. resinous substance, -talgseife, /. tallow-rosin soap, yellow household soap, -tanne, /. pitch fir. -teer, m. resinous tar. -wasser, n. resin water, -zahl,/. resin number rosin number, -zement, m. resinous cement, haschen, v.t. tk i. eatch, seize, haschieren, hatch hash, mince. 

At the end of the incubation period the fermentation culture mixture is adjusted to pH 2 with concentrated hydrochloric acid, the solid material present is removed by filtration, and the filter cake is washed with water. The washings are combined with the main filtrate, adjusted to pH 7.0, and 15.5 liters of the filtered culture liquid is introduced into a columnar exchanger d /a" i.d.) packed with 380 ml of carboxylic acid resin which has been preliminarily washed in succession with two liters of an aqueous solution of 37.5 grams of sodium hydroxide and with two liters of water. The column containing paromomycin is washed with two hold-up volumes of water and is eluted with 0.5 N hydrochloric acid. 

The trends of variation of the activation parameters are correlated with the solvation mechanism and dielectric behavior of the medium. Thus, AH, AG and A5 for the acidic resin-catalyzed hydrolysis of isopropyl acetate were calculated using the Wynne-Jones and Eyr-... 

Capacities at Various pH Values pKa Values for Phosphoric Acid Resin ... 

Both sulfuric acid and hydrofluoric acid catalyzed alkylations are low temperature processes. Table 3-13 gives the alkylation conditions for HF and H2SO4 processes. One drawback of using H2SO4 and HF in alkylation is the hazards associated with it. Many attempts have been tried to use solid catalysts such as zeolites, alumina and ion exchange resins. Also strong solid acids such as sulfated zirconia and SbFs/sulfonic acid resins were tried. Although they were active, nevertheless they lack stability. No process yet proved successful due to the fast deactivation of the catalyst. A new process which may have commercial possibility, uses... 

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