Relationships of Surfactant Head Group Weight Fraction and Some Polarity Terms by Gas Chromatography

 Polarity, partition coefficient (K), methanol carbon number of surfactant ((CMeOH)S), and methanol carbon number of surfactant head group ((CMeOH)HG) are measured on six alkanolamides and five polyoxyethylenated long chain amines as stationary phases. From the measured methanol carbon numbers, polarity indices, (IP)S and (IP)HG, are calculated. The determined polarity terms are plotted against the head group weight fraction ( fHG ) of the investigated surfactants and several equations have been developed. The study reveals that the molecular structural gap between alkanolamides and polyoxyethylenated long chain amines diminished when HLB numbers of these surfactant classes are plotted against fHG values. Consequently, a general equation relating HLB and fHG is obtained.     

乙醇胺类原料形成亚硝胺的比较

为了探究目前表面活性剂生产和应用中用脂肪酸甲基单乙醇酰胺或脂肪酸单乙醇酰胺替代脂肪酸二乙醇酰胺的趋势的可行性,本文首先采用亚硝酸叔丁酯法合成3种乙醇胺的亚硝胺化合物作为基准物,通过鉴定产物结构研究亚硝胺的形成历程,然后以亚硝酸法合成亚硝胺化合物,通过生成率比较3种乙醇胺形成亚硝胺化合物的难易程度。 亚硝化历程分析结果表明,二乙醇胺或甲基单乙醇胺均直接形成相应的亚硝胺,而单乙醇胺通过歧化反应生成二乙醇胺继而形成少量N-亚硝基二乙醇胺。 与二乙醇胺相比,甲基单乙醇胺或单乙醇胺更不易生成亚硝胺,因此用脂肪酸甲基单乙醇酰胺或脂肪酸单乙醇酰胺替代脂肪酸二乙醇酰胺是合理可行的。 本研究结果对保障人类生命健康安全具有理论和实践意义。     

Determination of Polarity Terms of Some Nitrogen-Containing Surfactants and Simulated Hydrophobic Tail Models by Gas Chromatography

Some polarity terms of two groups of nitrogen-containing surfactants （ six alkanolamides and nine polyoxyethylenated long chain amines） are measured through gas chromatography. The apparent methanol carbon number （CMeOH） and polarity index （IP） values are determined on the investigated surfactants as stationary phases in packed columns. Similarly, CMeOH and IP values are determined on simulated hydrophobic tail （SHT）models. The obtained results reveal that the introduction of SHT approach permits the distinction between the polarities of different surfactants and their head groups. The measured polarity terms are discussed as related to hydrophile-lipophile balance （HLB） number and the hydrophobic group carbon number （RCN）. Some equations relating the measured polarity values and these variable have been developed.