A phenol, a formaldehyde and an unsaturated compound having carbon-carbon double bond are reacted in the presence of a secondary amine and an acid at a temperature of 100.degree. to 250.degree. C., to give a chroman.
在100℃至250℃的温度下,在二级胺和酸的存在下,
苯酚、
甲醛和具有碳-碳双键的不饱和化合物反应,产生一种
色烷。