Donald R. Larkin

Preparation of detergents from formaldehyde

A process was developed for condensing different mol ratios of dodecanol, formaldehyde and ethylene oxide to form a series of adducts with useful detergent properties. These products are analogous to the commercially important class of nonionic surfactants produced by treating fatty alcohols with ethylene oxide to produce a homologous series of adducts. The structures were shown to be represented by RO[(CH2O)x(CH2CH2O)y]R where R is either dodecyl or hydrogen, x and y are integers (including zero), and it is understood that the oxymethylene and oxyethylene groups are intermingled in the ether chains. Unfortunately, we were unable to produce commercially viable detergent compositions. For these, our calculations indicate that a dodecanol:HCHO:EO mol ratio between 1:3:4 and 1:5:2 would be necessary both for good detergency and good economics. With acidic catalysts such as BF3, the condensation is facile and product with desired overall mol ratios can be produced. However, much of the formaldehyde and ethylene oxide are incorporated into by-products that either detract from the detergency properties (e.g., terminal ethers where both R groups are dodecyl) or make the mixtures unacceptable as detergents (e.g., 1,4-dioxane). Because of the presence of terminal ethers, the detergent properties are similar to those of propylene oxide adducts rather than ethylene oxide adducts. With selected basic catalysts most of the harmful by-products can be eliminated, but the reaction rates and conversions are unsatisfactory. Basic catalysts that give high reaction rates convert most of the formaldehyde fed to methyl formate.