Sulfuric acid hydrolysis

The sulfuric acid hydrolysis may be performed as a batch or continuous operation. Acrylonitrile is converted to acrylamide sulfate by treatment with a small excess of 85% sulfuric acid at 80—100°C. A hold-time of about 1 h provides complete conversion of the acrylonitrile. The reaction mixture may be hydrolyzed and the aqueous acryhc acid recovered by extraction and purified as described under the propylene oxidation process prior to esterification. Alternatively, after reaction with excess alcohol, a mixture of acryhc ester and alcohol is distilled and excess alcohol is recovered by aqueous extractive distillation. The ester in both cases is purified by distillation. 

Hydrolysis. Aluminum alkoxides are hydrolysed using either water or sulfuric acid, usually at around 100°C. In addition to the alcohol product, neutral hydrolysis gives high quaUty alumina (see Aluminum compounds) the sulfuric acid hydrolysis yields alum. The cmde alcohols are washed and then fractionated. 

Mild steel is a satisfactory constmction material for all equipment in Ziegler chemistry processes except for hydrolysis. If sulfuric acid hydrolysis is employed, materials capable of withstanding sulfuric acid at 100°C are requited lead-lined steel, some alloys, and some plastics. Flow diagrams for the Vista and Ethyl processes are shown in Eigures 3 and 4, respectively. 

Relatively pure xylan isolated from the holocellulose of aspen (Populus) wood is said to contain 85% of xylose residues.78 One of the characteristic properties of xylan is its ease of hydrolysis. Because it hydrolyzes much more readily than cellulose, mild acid treatment may be employed to bring about preferential hydrolysis of xylan from plant material. Xylose is ordinarily prepared in the laboratory by direct sulfuric acid hydrolysis of the native xylan in ground corn cobs.74 Hydrolysis in hydrochloric acid proceeds rapidly, but decomposition to furfural also occurs to some extent.76 A commercial method for the production of D-xylose from cottonseed hulls76 and straw77 and from corn cobs17 78 has been described. 

Hot, dilute sulfuric acid hydrolysis of 10, R = alkyl, aryl initially gives anthranilic acid, which is converted into salicylic acid on prolonged reaction. When dilute hydrochloric acid is employed with the same substrates iV-alkyl- and AT-arylsalicylamides are formed, but concentrated hydrochloric acid results in the formation of o-chlorobenzoic acid. - ... 

Following hydrogenation over palladium on carbon(33), dimethyl adipate hydrolysis to adipic acid is carried out using a strong mineral acid such as sulfuric acid. Hydrolysis is nearly quantitative with a selectivity of 99.5%. Since the adipic acid from the oxycarbonylation process contains no branched by-product acids, as is the case with the commercial oxidation process, extensive recrystallization is not required to produce a polymer grade material. Results indicate that the dried adipic acid crystals contain less than. 5 weight % moisture and are 99.95 weight % pure on a dry basis. 

The isolated dimethyl sebacate can be sold commercially as is or optionally hydrolyzed to sebacic acid. If a higher molecular weight plasticizer diester is required, a transesterification with -ethyl hexanol, for example, gives the desired product plus two equivalents of methanol which is recycled back to the oxycarbonylation reaction. If the free acid is desired, dimethyl sebacate hydrolysis to sebacic acid is carried out using a strong mineral acid such as sulfuric acid. Hydrolysis is nearly quantitative with a selectivity of about 99.5% to diacid and. 5% to the half-ester acid product. Additional recrystallization is used to improve purity if required. 

Methylcoumarins bearing hydroxy and other electron-donating groups can be synthesized from the corresponding phenols by reaction with ethyl acetoacetate in the presence of sulfuric acid. Hydrolysis of the ester group in the product then allows the lactone ring of the coumarin to form (Scheme 5.6). 

This study reports the first application of universal calibration via HPSEC-DV to four acetylated hardwood lignins obtained from aspen (Pop-ulus tremuloides) wood meal by ball milling and solvent extraction steam explosion followed by alkaline extraction organosolv pulping followed by water extraction of the associated sugars and dilute sulfuric acid hydrolysis followed by sodium hydroxide extraction. 

For example, 3 can be prepared from sulfuric acid hydrolysis of the cycloaddition product of ethynylbenzene and trifluorochloroethene (Section 13-3D) ... 

Basic Protocol 2 Determination of Noncellulosic Neutral Sugars and Cellulose Content by Trifluoroacetic Acid Hydrolysis Followed by Sulfuric Acid Hydrolysis E3.2.4... 

DETERMINATION OF NONCELLULOSIC NEUTRAL SUGARS AND CELLULOSE CONTENT BY TRIFLUOROACETIC ACID HYDROLYSIS FOLLOWED BY SULFURIC ACID HYDROLYSIS... 

Retain the pellet, i.e., TFA-insoluble material, and proceed with two-stage sulfuric acid hydrolysis in step 6. 

Hydrolyze TFA-insoluble residue with a two-stage sulfuric acid hydrolysis... 

A comparison of a TFA hydrolysis with a sulfuric acid hydrolysis (Table I) demonstrates that all sugars—but not glucose—are obtained in higher yield with TFA than with sulfuric acid this is evidence for the controlled action of TFA. 

The whole procedure normally takes about 1 hr. The acid is then evaporated, and the dry matter can be analyzed. This method can be applied to cellulose from wood, as a-cellulose or pulp, or to other celluloses (e.g., cotton) as well as to cellulosic materials with higher amounts of other polysaccharides (e.g., holocellulose). The chromatograms of the hydrolysates of a-cellulose from beechwood and of holocellulose from sprucewood (Figure 6) are examples of the application of this method. Compared with sulfuric acid hydrolysis, the total sugar yield from the spruce holocellulose is higher after the hydrolysis with concentrated TFA (Table II). Regarding the individual sugars, it can be seen that the... 

A new model for the dilute acid hydrolysis of cellulose was developed at FPL in connection with studies of the two-stage dilute sulfuric acid hydrolysis process (Fig. 28.18).37 The model incorporates the effect of the neutralizing capacity of the substrate, the presence of readily hydrolyzable cellulose, and the reversion reactions of glucose in acid solution. Although general in nature, the model was developed specifically for application to... 

Wright, J. and d Agnicourt, C. In Evaluation of Sulfuric Acid Hydrolysis for Alcohol Fuel Production, Biotechnology and Bioengineering Symposium, 1984 John Wiley and Sons New York, 1984 pp. 105-123. 

Harris, J., Baker, A., Conner, A., Jefferies, T., Minor, J., et al., Two-Stage Dilute Sulfuric Acid Hydrolysis of Wood An Investigation of Fundamentals General Technical Report FPL-45 U.S. Forest Products Laboratory Madison, WI, 1985. 

Wright, J. D. and D Agincourt, C. G., Evaluation of sulfuric acid hydrolysis processes for alcohol fuel production. Biotechnology and Bioengineering Symp. 1984, 14, 105-121. 

Chloroprene is dimerized to 54 when heated. When the dimer is treated with sulfuric acid, hydrolysis to 1,4-cyclooctanedione occurs and this diketone experiences transannular closure under the reaction conditions.100 ... 

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