Fatty amides (saturated, C
6, 8, 10, 12, 14, 16, 18 and C
22; cis and trans forms, Δ9-C
18F, Δ11-C
20F and Δ13-C
22F) and N, N'-methylenebisamides (saturated, C
6, 8, 10, 12, 14, 16, 18 and C
22; cis-form, Δ9-C
18F, Δ11-C
20F and Δ13-C
22F ; trans-form, Δ9-C
18F) were prepared, and subjected to measure melting point and thermal stability. The stability was measured with thermobalance. Purity of each compound was more than 99% by gas chromatography.
Saturated N, N'-methylenebisamides melt between 175.5°C(C
6) and 141.9°C(C
22), and the melting points go down according to increse of carbon number. On the other hand, saturated simple amides (C
6 to C
22) melt at various temperatures in the region from 100 to 110°C.
Melting points of unsaturated simple amides are as follows : oleamide, 76.2°C;
cis-11-eicosenamide, 79.3°C; erucamide, 83.5°C ; elaidamide, 91.2 °C ; trans-11-eicosenamide, 91.2°C ; and brassidamide, 95.0°C.
Also, melting points of unsaturated N, N'-methylenebisamides are as follows :
cis-form, C
18F, 118.1°C ; C
20F, 122.3°C ; C
22F, 123.8°C ; trans-form, C
18F, 131.2°C.
Thermal stability of saturated simple amides (C
12 to C
22) increase with addition of methylene group, and the thermogravimetric curves are parallel to each other. Stability of unsaturated simple amides (
cis-form, C
18F to C
22F) are somewhat larger than that of saturated simple amides (C
18 to C
22). Saturated (C
10 to C
22) and unsaturated N, N'-methylene bisamides have larger thermal stability than that of simple amides having the same carbon atoms because of higher molecular weight. Stability of C
10 bisamide containing 21 carbon atoms is similar to that of C
20 simple amide. However, the stability of C
18 bisamide containing 37 carbon atoms is nearly equal to that of C
22 simple amide.
Thermal stability of unsaturated bisamides is similar to that of saturated bisamides.
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