Science Record

(1

atom, the oxygen atom in the molecule of iso-octyl alcohol thus carries less negative charge than that in the molecule of normal octyl alcohol. Again we consider the more important step in hydrogen ion catalysis in esterification:

OH OH

| | Bact + a — R-C—O—R’ —> RCOOR’ +H:0 + Ht. | | OH #H OHH* It is clearly shown that the more negative charge the oxygen atom carries, the easier the esterification reaction proceeds. This explains why the velocity constant for the reaction of sebacic acid with normal-octyl alcohol is rather greater than that of sebacic acid with iso-octyl alcohol.

q . : —

7 o/ib0

2 Y, 150

3 [LK “140

0 4 a: fp 12 - A ib 2b t(hr.)

Fig. 2 Reactions of equivalent quantity ratio of sebacic acid with iso-octyl alcohol at different temperatures,

The results of the esterification reaction between an equivalent quantity ratio of sebacic acid and normal-octyl alcohol at 160°C, or between an equivalent quantity ratio of sebacic acid and iso-octyl alcohol at 150°C in the presence of sulfuric acid as catalyst, treated by means of equation (2), are plotted in Figs. 4 and 5, and shown in Tables 3 and 4. All the results are in conformity with the second order reaction. Tables 3 and 4 show obviously that by increasing the concentration of hydrogen ion derived from the sulfuric acid, the rate of esterification is greatly increased. Though the time of esterification is shortened as the rate of reaction increases, yet the products have a