Homogeneous base‐catalyzed isomerization of linoleic acid: Toward high selectivity of bioactive c9,t11 and t10,c12‐ <scp>CLA</scp> isomers

Abstract BACKGROUND Conjugated linoleic acid (CLA), particularly the bioactive isomers c9,t11‐CLA, and t10,c12‐CLA, has garnered substantial attention in food, nutraceutical, and pharmaceutical fields due to its diverse physiological benefits. However, the efficient synthesis of CLA with high selectivity toward bioactive isomers and satisfactory yield remains a challenge in homogeneous catalytic systems. RESULTS We systematically investigated the effects of key reaction parameters – including temperature, time, catalyst dosage, and alcohol‐to‐oil ratio – on the conversion of linoleic acid (LA) and the selectivity of target CLA isomers in a homogeneous base‐catalyzed isomerization process. The chemical composition and structural characteristics of the resulting CLA products were comprehensively characterized via Fourier transform infrared spectroscopy (FT‐IR), ultraviolet–visible spectroscopy (UV‐visible), gas chromatography (GC), and gas chromatography–mass spectrometry (GC–MS). Four CLA isomers were identified, namely c9,t11‐CLA, t10,c12‐CLA, t10,t12‐CLA, and t9,t11‐CLA, with the bioactive c9,t11‐CLA and t10,c12‐CLA as the predominant components. Through univariate optimization combined with parallel validation experiments, the optimal reaction conditions were determined as follows: stirring rate of 800 r/min, reaction temperature of 185 °C, reaction time of 4.5 h, catalyst (Sodium ethoxide) dosage of 30 wt%, and alcohol (Ethylene glycol) ‐to‐oil ratio of 10 mL/g. Under these optimized conditions, the relative content of bioactive CLA isomers reached nearly 90% – a performance that outperforms many conventional homogeneous catalytic systems for LA isomerization. CONCLUSION This study provides a systematic and scalable approach for the efficient synthesis of high‐purity, bioactive‐enriched CLA, offering valuable insights into the rational design of homogeneous catalytic processes for lipid modification and meeting the industrial demand for high‐quality CLA products. © 2026 Society of Chemical Industry (SCI).