There was a marked difference between the thermal behavior of N-(perfluoroacyl) ethylenediamine (NF) with Rf=C3F7- or C7F15- and that of conventional N-acylethylenediamine (NH), heating to 100240°C under nitrogen gas. At low temperature, the cyclization rate of NF was slower than that of NH. The kind of product depended on n in a structure (-CF2-)n, where the main product was N, N'-bis (perfluoroacyl) ethylenediamine (NB) when n=3 and 2-(perfluoroalkyl)-2-imidazoline (FI) when n=7. At high temperature, defluorination occurred with heating longer than 3h, and the rate was accelarated by the addition of CaO.
A rapid method has been devised for the GC-MS determination of double bond positions in monounsaturated fatty acids as their dimethyl disulfide adducts. As a standard procedure for the single-step preparation of adducts, fatty acid methyl esters were incubated with dimethyl disulfide in the presence of I2 as the catalyst for 30min. After the reduction of I2 with NaHSO3, hexane-ether mixture was added to the resulting system, and the upper phase was injected directly into a GC-MS. When the original esters contained a large quantity of polyenoates, TLC purification was used to remove contaminating by-products from the polyenoates before conducting the GC-MS analysis. The adducts of monoenoates had relatively shorter retention times under the GC-MS conditions, and gave simple mass spectra and easily recognizable molecular ions. The cleavage between the methylthio-substituted carbons gave key fragment ions showing the original double bond positions in the aliphatic chain. This method was applied to the fatty acid analysis of naturally-occurring lipids, such as chlorella, parsley seed and soybean lipids. The positional isomers, 14:1 (n-9, n-7 and n-5), 16:1 (n-9, n-7 and n-5), 18:1 (n-9 and n-7), and 17:1 (n-8), could be readily detected in chlorella, 18:1 (n-12, n-9 and n-7) in parsley seed, and 18:1 (n-9 and n-7) in soybean.
Four series (anionic, cationic, zwitter-ionic and POE nonionic) of surfactants with peptide joints were prepared from various N-dodecyl-α-amino acids (Scheme-1, Table-1). The aqueous properties (Krafft point, cloud point, cmc, surface tension) and gross effects (foaming, emulsifying, detergency) of these products were examined and compared with those of surfactants without peptide joints for each series. The effects of peptide joints on aqueous properties were found to depend primarily on the hydrophobicity of the α-amino acid used (Table-6, -7). Glycine and alanine joints generally caused on increase in hydrophilicity and a slight change in cmc and surface tension for all series studied. Some nonionics having hydrophilic peptide joints and shorter POE chains had both Krafft and cloud points in the temperature range from 2090°C and exibited high surface activity (Table-7). These nonionics were effective emulsifying agents (O/W) against relatively polar oils (Fig. -4) and showed good detergency (Table-8), The surfactants with peptide joints were highly biodegradable.