Table 2 Main spectroscopic data and reaction times of FMAs on pure copper and copper-zinc surfaces
Acids | m.p., °C a | Cu | Cu–Zn | Notes | ||
|---|---|---|---|---|---|---|
Consumption time b | Carboxylate maxima (vas, cm−1) | Consumption time b | Carboxylate maxima (vas, cm−1) | |||
C6 | −3.2 | – | n.d | 35 min (25 °C) | Cu: 1612 (w, int.), 1582 Zn: 1526 (s) | Evaporation of FA is sufficiently fast, interfering with reaction; consumption rate is lower in the first stages that the intermediate at 1614 cm−1 is produced |
C8 | 15.4 | 2 h 50 min (25 °C) | 1612 (w, int.), 1584 (s), 1510 (w) |  > 1 h (13 °C)  ~ 50 min (28 °C) | Cu: 1612 (w, int.), 1582 Zn: 1526 (s) | |
C10 | 31.0 | 3 h 40 min (20 °C) | 1615 (vw, int.), 1581 (s), 1510 (w) | 4 h (19 °C) | Cu: 1612 (w, int.), 1586 (s) Zn: 1550 (m-s), 1523 (m-s) | Evaporation of FA interferes with reaction |
C12 | 44.8 |  ~ 8 days (20 °C) | 1582 (s), 1512 (w) | 14 h (20 °C) | Cu: 1585 (s) Zn: 1537 (s) | After forming the first carboxylate amounts, no other compounds or intermediates were formed |
C14 | 54.4 |  ~ 5.5 days (20 °C) | 1586 (s) | 2.5 days (20 °C) | Cu: 1584 (s) Zn: 1537 (s) | |
C16 | 62.9 |  > 18 days (40 °C) | 1585 (s) |  ~ 24 days (40 °C) | Cu: 1584 (s) Zn: 1539 (s) | |
C18 | 70.1 |  > 20 days (40 °C) | 1585 (s) |  ~ 20 days (30 °C)  ~ 15 days (40 °C) | Cu: 1587 (s) Zn: 1539 (s) | |