Specifications, commercial formaldehyde solutions

Specifications and Analytical Methods. The commercial aqueous solution is specified as 34% minimum butynediol, as determined by bromination or refractive index. Propargyl alcohol is limited to 0.2% and formaldehyde to 0.7%. 

In addition to the usual 37 per cent methanol-stabilized formaldehyde, solutions which contain less than 1 per cent methanol are also encountered in some instances. Products of this type containing 30 and 37 per cent formaldehyde, respectively, may be cited as specific examples of special commercial solutions. ... 

In general, commercial formaldehyde is a uniform solution of high purity capable of meeting stringent pioduct requirements. The following figures are representative of typical product specifications. 

Formaldehyde—Alcohol Solutions. These solutions are blends of concentrated aqueous formaldehyde, the alcohol, and the hemiacetal. Methanol decreases the average molecular weight of formaldehyde oligomers by formation of lower molecular weight hemiacetals. These solutions are used to produce urea and melamine resins the alcohol can act as the resin solvent and as a reactant. The low water content can improve reactivity and reduce waste disposal and losses. Typical specifications for commercially available products are shown in Table 7 (117). 

I. Since commercial solutions of formaldehyde contain methyl alcohol, it is grossly inaccurate to estimate the amount of formaldehyde present by reference to specific gravity tables (. Org. 83m. 14, 92). The formaldehyde content of the solution is determined by analysis, for which the iodimetric method of Borgstrom and Horsch is recommended. The yield is calculated upon the basis of the amoimt of formaldehyde actually present, as shown by analysis. 

Novolac resins are produced commercially from cresol mixtures that contain amounts of m-cresol and p-cresol isomers in varying proportions, depending on the specific application. The reaction proceeds with both metal cation and acid catalysis (Scheme 1.1) Because of strict guidelines for metallic contaminants in semiconductor grade process materials and chemicals, acid catalysis is employed in the synthesis of novolacs used in photoresist applications. In a typical commercial production process, a mixture of m- and p-cresol isomers, formaldehyde (most often in the form of formalin, a 35-40% aqueous solution of formaldehyde) and an oxalic acid catalyst are reacted, following the description of Pampalone ... 

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