Condensation of Octadecene-1 with Formaldehyde

Abstract

Authors investigated the condensation of octadecene-1 with formaldehyde in acetic acid at the presence of perchloric acid as, the catalyst.
The reaction products were saponified and fractionated by recrystallization and chromatography, and three substances were separated. The characteristics of these substances were corresponded to those of nonadecadiol-1, 3 (mp 75-75.5°C), 3-pentadecatetrahydropyranol-4 (mp 65-66°C) and octadecanol (mp 41-44°C., mixture of alkanol-2 and-3), respectively.
The presence of alkyl-1, 3-dioxan, known as one of the main products of lower olefine condensed with formaldehyde, was also recognized in this case from IR spectrum of the lower melting fractions of the filtrate, but it was not isolated because of its small quantity.
As the catalyzer, perchloric acid was more effective than followed sulfuric acid and borontrifluoride etherate in the above reactions. The larger the quantity of paraformaldehyde used against olefine, the greater the yield of the products obtained, but more pyranol was obtained in case of 1 : 1 molar ratio than other cases (Table 1).
The saponification value of the product was the highest at 3 hr reaction time, and the reaction was seemed to proceed easily (Fig. 4).
Octadecene-1 did not react with formaldehyde without acetic acid in inert solvent such as ethanol or in the presence of 50% acetic acid, also it did not react with aqueous formalin even in acetic acid (Table 3).