Phosphonic acids are the only phosphorus-containing organic compounds
detected in the Murchison meteorite. We earlier described the synthesi
s of methyl-, hydroxymethyl-, and 1-hydroxyethyl phosphonic acids usin
g sodium phosphite as a source of phosphite radicals. We now show that
ultraviolet irradiation of dilute aqueous solutions of acetylene in t
he presence of sodium phosphite leads to the synthesis of vinyl phosph
onic acid. At neutral to basic pH, vinyl phosphonic acid reacts under
photochemical conditions to produce phosphonoacetaldehyde and 2-hydrox
yethyl phosphonic acid as the major products, as well as smaller yield
s of l-hydroxyethyl phosphonic acid, phosphonoacetic acid, and ethyl p
hosphonic acid. Of these products, phosphonoacetaldehyde is particular
ly interesting as a potential precursor of prebiotic carbohydrate deri
vatives.