全氟辛基磺酸酸度函数H_0的测定

THE MEASUREMANT OF THE ACIDITY FUNCTION H_0 OF PERFLUOROOCTANESULFONIC ACID

全氟辛基磺酸(POSA,perfluorooctanesulfonic acid)是一个熔点90℃的固体超酸,测定POSA酸度函数H_0值是一个一直未能解决的问题。G.A.Olah将所有全氟烷基磺酸C_nF_(2n+1)SO_3H都划归超酸范围,但迄今只有液态和低熔点固态的C_1、C_2、C_4和C_6的全氟烷基磺酸测定过H_0值,因而测定POSA酸度函数H_0值的意义不仅在于首次测出了POSA酸度函数H_0的确切数值,明确了POSA确系酸度比百分之百硫酸更强的超酸,而且开辟了C_7以上固体全氟烷基磺酸H_0的测定方法和途径,进而可以建立这一全氟烷基同系列的酸度函数H_0值的线性关系、结构影响等。

It is reported in this paper that the acidity function H_0 of perfluorooctanesulfonic acid (POSA) is -12.11±0.03, which was measured first time by ~1H NMR method, in term of the α-H chemical shifts of the acid-ether systems, using 98% to 100% H_2SO_4 as reference standards. This method provides a new procedure for measuring the H_0 value of solid perfluoroalkanesulfonie acid C_nH_(2n+1)SO_3H(n>7).