The fatty acid derivatives, prepared from renewable natural oils, can be used as highly promising and potential substitutes for petrochemicals. The study of process improvement and stereochemical mechanism for preparing these derivatives would be beneficial for their industrial production. Conjugated linoleic acid (CLA) containing 9cis-11trans (9c, 11t) and 10trans-12cis (10t, 12c) isomers was prepared from Salicornia herbacea seed oil. Maleic anhydride cycloadduct of CLA (MAC) was prepared by an improved process, and it was characterized by FTIR, 1H and 13C NMR, etc. A new method to calculate conformers-ratio of CLA or MAC was also developed. Furthermore, the stereochemical mechanism for the improved preparation of MAC was proposed primarily by the calculation method above. The following observations were made: 1) The yield of MAC could reach as high as 96.7% under mild reaction conditions and with an easy and efficient product separation; 2) The trans-trans CLA in the s-cis conformation acted as a predominant reactant to Diels-Alder [4 + 2] cycloaddition of maleic anhydride, which was the main reaction occurred simultaneously with catalytic configurational isomerizations of CLA in one step; 3) From all studied CLA conformers, the most stable conformation was the s-trans conformation of trans-trans CLA, while the s-cis conformation of trans-trans CLA had the most favorable structural parameters for cyclohexenyl ring formation; 4) Four MAC conformers derived from 9c, 11t- and 10t, 12c-CLA, were obtained as final main products that were determined to be cis-cycloadducts; 5) The endo/exo ratios of the cis- cycloadducts derived from 9c, 11t- and 10t, 12c-CLA, were 2.14:1 and 1.99:1, respectively; and 6) The results obtained from the calculation method above were in excellent accordance with those from our experiments.
References
[1]
Sullivan, M.J., Binette, M.L. and Aoyama, S. (2019) Two-Piece Golf Ball Comprising Highly Neutralized Polymer Layer. Acushnet Company, New Bedford.
[2]
Huang, K., Zhang, P., Zhang, J.W., Li, S.H., Li, M., Xia, J.L. and Zhou, Y.H. (2013) Preparation of Biobased Epoxies Using Tung Oil Fatty Acid-Derived C21 Diacid and C22 Triacid and Study of Epoxy Properties. Green Chemistry, 15, 2466-2475. https://doi.org/10.1039/c3gc40622a
[3]
Ursula, B., Anton, J. and Juergen, O.M. (2012) Esters of Maleinized Fatty Compounds as Plasticizers. European Journal of Lipid Science and Technology, 114, 49-54. https://doi.org/10.1002/ejlt.201100136
[4]
Watanabe, S., Fujita, T., Fukuda, S., Hirano, K. and Sakamoto, M. (1986) Characteristic Properties as Cutting Fluid Additives of the Products from the Reaction of Unsaturated Fatty Acids with Maleic Anhydride. Materials Chemistry and Physics, 15, 89-96. https://doi.org/10.1016/0254-0584(86)90091-X
[5]
Moreno, M., Victoria Gomez, M., Cebrian, C., Prieto, P., Hoza, A. and Moreno, A. (2012) Sustainable and Efficient Methodology for CLA Synthesis and Identification. Green Chemistry, 14, 2584-2594. https://doi.org/10.1039/c2gc35792e
[6]
Ojha, D.P. (2005) Ordering of a Thermotropic Mesogen at Phase Transition Temperature-A Statistical Approach Based on Quantum Mechanics. Journal of Theoretical & Computational Chemistry, 4, 803-810. https://doi.org/10.1142/S0219633605001805
[7]
Hartung, J., Daniel, K., Rummey, C. and Bringmann, G. (2006) On the Stereoselectivity of 4-penten-1-oxyl Radical 5-exo-trig Cyclizations. Organic & Biomolecular Chemistry, 4, 4089-4100. https://doi.org/10.1039/b611473c
[8]
Jin, P., Yang, L., Liu, C., Chen, M. Q., Hou, Q. H., Li, L. L. and Zhao, Y. J. (2017) A Comparative Study on the N-Heterocyclic Carbene Adducts of Ih-C60, D5h-C70 and Sc3N@Ih-C80. Physical Chemistry Chemical Physics, 19, 17598-17606. https://doi.org/10.1039/C7CP02696J
[9]
Liu, Q., Chen, C.J., Zhang, L. and Gao, K. (2016) Two New Indole Alkaloids from Hunteria Zeylanica. Journal of Asian Natural Products Research, 18, 349-353. https://doi.org/10.1080/10286020.2015.1092961
[10]
El Merbouh, B., Bourjila, M., Tijar, R., El Bouzaidi, R.D., El Gridani, A. and El Mouhtadi, M. (2014) Conformational Space Analysis of Neutral and Protonated Glycine Using a Genetic Algorithm for Multi-Modal Search. Journal of Theoretical & Computational chemistry, 13, Article No. 1450067. https://doi.org/10.1142/S0219633614500679
[11]
Chin, S.F., Liu, W., Storkson, J.M., Ha, Y.L. and Pariza, M.W. (1992) Dietary Sources of Conjugated Dienoic Isomers of Linoleic Acid, a Newly Recognized Class of Anticarcinogens. Journal of Food Composition and Analysis, 5, 185-197. https://doi.org/10.1016/0889-1575(92)90037-K
[12]
Arrieta, A., Cossio, F.P. and Lecea, B. (2001) Direct Evaluation of Secondary Orbital Interactions in the Diels-Alder Reaction between Cyclopentadiene and Maleic Anhydride. Journal of Organic Chemistry, 66, 6178-6180. https://doi.org/10.1021/jo0158478
[13]
Eulitz,K., Yurawecz, M.P., Sehat, N., Fritsche, J., Roach, J.A.G., Mossoba, M.M., Kramer, J.K.G., Adlof, R.O. and Ku, Y. (1999) Preparation, Separation and Confirmation of the Eight Geometrical cis/trans Conjugated Linoleic Acid Isomers 8,10- through 11,13-18:2. Lipids, 34, 873-877. https://doi.org/10.1007/s11745-999-0435-z
[14]
Arca, M., Sharma, B.K., Price, N.P.J., Perez, J.M. and Doll, K.M. (2012) Evidence Contrary to the Accepted Diels-Alder Mechanism in the Thermal Modification of Vegetable Oil. Journal of the American Oil Chemists Society, 89, 987-994. https://doi.org/10.1007/s11746-011-2002-x
[15]
Wu, Y., Yang, R.Q., Chen, M.Z. and Liao, X.B. (2012) Antitumor Activity of Conjugated Linoleic Acid Converted from Linoleic Acid in Salicornia herbacea Seed Oil. Food Science, 33, 318-322. (In Chinese)
