Methylaminoantipyrine was condensed with formaldehyde to form bis (4-methylaminoantipyrine) methane,which in turn was reacted with formaldehyde and sodium bisulfite to yield analgin in better quality.

• 以水作溶剂，由4-甲胺基安替比林与甲醛反应，缩合成双（4-甲胺基安替比林）甲烷，再以酒精作溶剂，与甲醛、亚硫酸氢钠缩合生成安乃近。