Formaldehyde purification

Apparatus for preparing liquid formaldehyde. Purification step. (From Walker, J. F., J, Am. Chem. Soc., 55, 2825 (1935).)... 

Although there is a substantial body of information in the pubHc domain concerning the preparation of polyacetals, the details of processes for manufacturiag acetal resins are kept highly confidential by the companies that practice them. Nevertheless, enough information is available that reasonably accurate overviews can be surmised. Manufacture of both homopolymer and copolymer involves critical monomer purification operations, discussion of which is outside the scope of this article (see Formaldehyde). Homopolymer and copolymer are manufactured by substantially different processes for accomplishing substantially different polymerisation chemistries. 

Commercial VPO of propane—butane mixtures was in operation at Celanese Chemical Co. plants in Texas and/or Canada from the 1940s to the 1970s. The principal primary products were acetaldehyde, formaldehyde, methanol, and acetone. The process was mn at low hydrocarbon conversion (3—10%) and a pressure in excess of 790 kPa (7.8 atm). These operations were discontinued because of various economic factors, mainly the energy-intensive purification system required to separate the complex product streams. 

In the manufacture of 2-naphthalenol, 2-naphthalenesulfonic acid must be converted to its sodium salt this can be done by adding sodium chloride to the acid, and by neutralizing with aqueous sodium hydroxide or neutralizing with the sodium sulfite by-product obtained in the caustic fusion of the sulfonate. The cmde sulfonation product, without isolation or purification of 2-naphthalenesulfonic acid, is used to make 1,6-, 2,6-, and 2,7-naphthalenedisulfonic acids and 1,3,6-naphthalenetrisulfonic acid by further sulfonation. By nitration, 5- and 8-nitro-2-naphthalenesulfonic acids, [89-69-1] and [117-41-9] respectively, are obtained, which are intermediates for Cleve s acid. All are dye intermediates. The cmde sulfonation product can be condensed with formaldehyde or alcohols or olefins to make valuable wetting, dispersing, and tanning agents. 

Some alkylphenol appHcations can tolerate "as is" reactor products, most significantly in the production of alkylphenol—formaldehyde resins. These resins can tolerate some of the reactant and by-product from the alkylphenol reactor because they undergo purification steps. This resin production route has both capital and operating cost advantages over using purer alkylphenol streams as feedstock. For these savings, the resin producer must operate the process in such a way as to tolerate a more widely varying feedstock and assume the burden of waste disposal of some unreactive materials from the alkylphenol process. 

Fiaal purification of propylene oxide is accompHshed by a series of conventional and extractive distillations. Impurities ia the cmde product iaclude water, methyl formate, acetone, methanol, formaldehyde, acetaldehyde, propionaldehyde, and some heavier hydrocarbons. Conventional distillation ia one or two columns separates some of the lower boiling components overhead, while taking some of the higher boilers out the bottom of the column. The reduced level of impurities are then extractively distilled ia one or more columns to provide a purified propylene oxide product. The solvent used for extractive distillation is distilled ia a conventional column to remove the impurities and then recycled (155,156). A variety of extractive solvents have been demonstrated to be effective ia purifyiag propylene oxide, as shown ia Table 4. 

Other options for the purification of CA include dissolution in hot water, aqueous ammonia, aqueous formaldehyde, or hot dimethylformamide followed by filtration to remove most of the impurities. The CA is recoverable by cooling the aqueous solution (84), acidifying the ammonium hydroxide solution (85), or cooling the dimethylform amide solution with further precipitation of CA by addition of carbon tetrachloride (86). Sodium hydroxide addition precipitates monosodium cyanurate from the formaldehyde solution (87). 

Ethylene Oxide Purification. The main impurities ia ethylene oxide are water, carbon dioxide, and both acetaldehyde and formaldehyde. Water and carbon dioxide are removed by distillation ia columns containing only rectifying or stripping sections. Aldehydes are separated from ethylene... 

Absorption is widely used as a raw material and/or product recovery technique in separation and purification of gaseous streams containing high concentrations of VOC, especially water-soluble compounds such as methanol, ethanol, isopropanol, butanol, acetone, and formaldehyde. Hydrophobic VOC can be absorbed using an amphiphilic block copolymer dissolved in water. However, as an emission control... 

Nitrogen, purification of, 41, 97 Nitromethane in condensation with formaldehyde, 41, 67 1-Nitro-l-methylcyclohexane, 43, 89... 

Roy R, S Mukund, GJ Schut, DM Dunn, R Weiss, MWW Adams (1999) Purification and molecular characterization of the tungsten-containing formaldehyde ferredoxin oxidoreductase from the hyperthermophilic archaeon Pyrococcus furiosus the third of a putative five-member tungstoenzyme family. J Bacteriol 181 1171-1180. 

Jahns T, R Schepp, H Kalytwasser (1997) Purification and characterization of an enzyme from a strain of Ochrobactrum anthropi that degrades condensation products of urea and formaldehyde (ureaform). Can J Microbiol AE. 1111-1117. 

P 48] Initially, a solution of 2.0 mM formaldehyde in methanol (5 pi min ) and pure methanol (5 pi min ) were fed through a bifurcation-distributive chip micro mixer [25]. The methanol stream was replaced by a methanol solution of 2.0 mM isocyanide and 0.2 mM amine salt. The reaction was carried out at room temperature and no purification steps were applied. 

Goelz SE, Hamilton SR, Vogelstein B. Purification of DNA from formaldehyde-fixed and paraffin-embedded tissue. Biochem. Biophys. Res. Commun. 1985 130 118-126. 

Recently, Vasilescu et al. demonstrated the use of formaldehyde to preserve protein interactions in vivo followed by immunoaffinity purification of a targeted complex, cross-link reversal via heating at 95°C, separation by SDS-PAGE, and identification of bands by LC-MS/MS.7 Tagwerker et al. utilized formaldehyde cross-linking in conjunction with a novel tag-based affinity purification method.36... 

In one successful procedure,UJhowever, cellulose was dissolved in dimethylsulfoxide in the presence of formaldehyde to yield clear viscous solutions. These methyloylcellulose derivatives were then reacted with anhydrides in the presence of pyridine to form esters. " The major advantage of the reported method was that the intermediate methyloylcellulose derivative could be reacted directly without isolation or purification. 

The industrial synthesis of polyformaldehyde [poly(oxymethylene)] occurs by anionic polymerization of formaldehyde in suspension. For this the purification and handling of monomeric formaldehyde is of special importance since it tends to form solid paraformaldehyde. After the polymerization the semiacetal end groups have to be protected in order to avoid thermal depolymerization (Example 5-13). This is achieved by esterfication with acetic anhydride (see Example 5-7). As in the case of trioxane copolymers (see Sect. 3.2.3.2) the homopolymers of formaldehyde find application as engineering plastics. 

It is recommended that a reslurry of crude OSL in an organic solvent or 10% aqueous salt (e.g., NaHCOa) solution be performed to remove low-molecular-weight (mono-functional) species, waxes, and carbohydrates. This purification leads to an improvement in OSL reactivity and contributes to the usefulness of OSL as a PF resin extender or PF copolymer raw material. It is presumed that extraneous removed materials in the crude lignin react with formaldehyde but do not lead to productive cross-linking polymer formation. 

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