Hydration of acrylic acid

This paper reports measuremerts of reaction kinetics for sulfonation of maleic, fumaric, and acrylic acids by sulfite addition and for hydration of acrylic acid with catalysis by H2SO4 or cation exchange resin. The kinetics were measured by sampling of isothermal batch reactors. 

Acrylamide with a demand of 200,000 tons year" is one of the most important commodities in the world. It is used for the preparation of coagulators, soil conditioners, stock additives for paper treatment, and in leather and textile industry as a component of synthetic fibers. Conventional chemical synthesis involving hydration of acrylonitrile with the use of copper salts as a catalyst has some disadvantages rate of acrylic acid formation higher than acrylamide, by-products formation and polymerization, and high-energy inputs. To overcome these limits since 1985, the Japanese company Nitto Chemical Industry developed a biocatalyzed process to synthesize... 

In hydration experiments, acrylic acid was determined by ion exclusion chromatography (ICE) on a Dionex ion chromatograph. Hydroxypropionic acid was evident on the chromatograms, but was not quantified because of the lack of an adequate standard. Hydration was catalyzed at 100 to 140°C by 0.1 to 1.5 M H2SO4 or... 

This patent makes use of the phenomenon of forming CO2 hydrates to concenuate and separate organics from water or, more accurately stated, to separate water from organics. In the specific way the process is described it is applied to aqueous solutions containing quite high concentrations of acrylic acid. 

In one of the examples a 31 % solution of acrylic acid in water was contacted in a static vessel with a liquid CO2 at 25 °C and 850 psi at a ratio of 1.97 1 C02 solution. After equilibration the lower aqueous phase was withdrawn (the concenu-ation of residual acrylic acid in the withdrawn aqueous phase was not stated in the example). The top CO2-rich phase which contained a high concentration of acrylic acid and some water was then cooled to 0 °C to form white hydrate crystals. The crystals were separated from the liquid phase and the CO2 was evaporated. The resultant acrylic acid contained only 0.9% water. 

Acrylamide monomer is an important chemical commodity produced on a multihundred thousand ton scale for the production of polymers and copolymers. The preferred manufacturing process is by the catalytic hydration of acrylonitrile at 70-120 °C using reduced Raney copper as the catalyst the initial concentration of acrylonitrile being around 4 m. There are several shortcomings to this process, among which are the high level of acrylic acid formed and byproduct formation12, 3). 

Production of acrylamide (Fig. 13) by hydration of acrylonitrile under the action of the intracelluar nitrile hydratase in Rhodococcus rhodochrous (Nitto Chemical Industry Co., Ltd., fed-batch process). The annual production amounts to >30000 tons (see also Table 6). Acrylamide is one of the most important commodity chemicals and is required in large quantities as the pre-polymer of polyacrylamide that is widely used in polymer and floccu-lent applications. The advantages of this hydratase approach in comparison with the classical chemical nitrile hydration are higher product end concentration, quantitative yields, no formation of acrylic acid, no need for copper catalyst, and only five chemical/technical operations instead of seven [73,112,113,171]. An analogous process for nicotinamide is being commercialized by Lonza (see also section 6). 

An extensive work was carried out by Uchikawa l on the conduction calorimetry of superplasticizers, such as SNF (NS in the figure), lignosulfonate (LS), a co-polymer of acrylic acid with acrylic ester (PC), and a three dimensional polycondensate product of aromatic aminosulfonic acid with trimethyl phenol (AS) (Fig. 11). The first peak in the calorimetry corresponds to the heat of dissolution of alite, the heat of formation of the AFt phase, and the calcium hydroxide formation from free lime. The second peak corresponds to the heat of hydration of alite. The admixtures were found to accelerate the formation ofthe ettringite phase. At w/cratios ofO.3 and 0.5 and a later addition of the admixture, the appearance of the second peak was significantly delayed and the peaks were of lower intensity. Most retardation occurred with polycarboxylic acid and amninosulfonic acid-based admixtures (Fig. 11). DSC was used to determine the amount of lime formed at different times. The DSC results show that the addition of admixtures at different w/c ratios generally decreases the amounts of lime in the presence of superplasticizers (Fig. 12). 

There are two pathways for the degradation of nitriles (a) direct formation of carboxylic acids by the activity of a nitrilase, for example, in Bacillus sp. strain OxB-1 and P. syringae B728a (b) hydration to amides followed by hydrolysis, for example, in P. chlororaphis (Oinuma et al. 2003). The monomer acrylonitrile occurs in wastewater from the production of polyacrylonitrile (PAN), and is hydrolyzed by bacteria to acrylate by the combined activity of a nitrilase (hydratase) and an amidase. Acrylate is then degraded by hydration to either lactate or P-hydroxypropionate. The nitrilase or amidase is also capable of hydrolyzing the nitrile group in a number of other nitriles (Robertson et al. 2004) including PAN (Tauber et al. 2000). 

This concept covers most situations in the theory of AB cements. Cements based on aqueous solutions of phosphoric acid and poly(acrylic acid), and non-aqueous cements based on eugenol, alike fall within this definition. However, the theory does not, unfortunately, recognize salt formation as a criterion of an acid-base reaction, and the matrices of AB cements are conveniently described as salts. It is also uncertain whether it covers the metal oxide/metal halide or sulphate cements. Bare cations are not recognized as acids in the Bronsted-Lowry theory, but hydrated... 

AB cements are not only formulated from relatively small ions with well defined hydration numbers. They may also be prepared from macromolecules which dissolve in water to give multiply charged species known as polyelectrolytes. Cements which fall into this category are the zinc polycarboxylates and the glass-ionomers, the polyelectrolytes being poly(acrylic acid) or acrylic add copolymers. The interaction of such polymers is a complicated topic, and one which is of wide importance to a number of scientific disciplines. Molyneux (1975) has highlighted the fact that these substances form the focal point of three complex and contentious territories of sdence , namely aqueous systems, ionic systems and polymeric systems. 

Water occurs in glass-ionomer and related cements in at least two different states (Wilson McLean, 1988 Prosser Wilson, 1979). These states have been classified as evaporable and non-evaporable, depending on whether the water can be removed by vacuum desiccation over silica gel or whether it remains firmly bound in the cement when subjected to such treatment (Wilson Crisp, 1975). The alternative descriptions loosely bound and tightly bound have also been applied to these different states of water combination. In the glass-poly(acrylic acid) system the evaporable water is up to 5 % by weight of the total cement, while the bound water is 18-28 % (Prosser Wilson, 1979). This amount of tightly bound water is equivalent to five or six molecules of water for each acid group and associated metal cation. Hence at least ten molecules of water are involved in the hydration of each coordinated metal ion at a carboxylate site. 

Yokoyama, T. Hiraoko, K. (1979). Hydration and thermal transition of poly(acrylic acid) salts. Polymer Preprints of the American Chemical Society, Division of Polymer Chemistry, 20, 511-13. 

Figure 4.8 Cylindrical and spherical hydration regions around poly(acrylic acid) at various degrees of neutralization (or charge densities). Based on Ikegami (1964).

Hydration of polymeric membranes may be influenced by the chemical identity of the polymers. A hydrophilic polymer has a higher potential to hydrate than a hydrophobic one. Sefton and Nishimura [56] studied the diffusive permeability of insulin in polyhydroxyethyl methacrylate (37.1% water), polyhydroxy-ethyl acrylate (51.8% water), polymethacrylic acid (67.5% water), and cupro-phane PT-150 membranes. They found that insulin diffusivity through polyacrylate membrane was directly related to the weight fraction of water in the membrane system under investigation (Fig. 17). 

Ring opening of the pyrazole ring of 133 with benzylamine, ammonium hydroxide, and hydrazine hydrate takes place regioselectively affording the acrylic acid esters 134 (Equation 13) <2003MI1>. 

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