Prediction of retention indices. VI: Isothermal and temperature-programmed retention indices, methylene value, functionality constant, electronic and steric effects

A difference equation (DE) model is developed using the methylene retention increment (Δtz) of n-alkanes to avoid the influence of gas holdup time (tM). The effects of the equation orders (1st–5th) on the accuracy of a curve fitting show that a linear equation (LE) is less satisfactory and it is not necessary to use a complicated cubic or higher order equation. The relationship between the logarithm of Δtz and the carbon number (z) of the n-alkanes under isothermal conditions closely follows the quadratic equation for C3–C30 n-alkanes at column temperatures of 24–260 °C. The first and second order forward differences of the expression (Δlog Δtz and Δ2log Δtz, respectively) are linear and constant, respectively, which validates the DE model. This DE model lays a necessary foundation for further developing a retention model to accurately describe the relationship between the adjusted retention time and z of n-alkanes.

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“…The linear relationship (i.e., LE model) between logarithm of

t_{R z}^{'}

and carbon number ( z ) of the homologous n -alkanes under an isothermal GC condition has been widely used since the 1950s [1,2,22,23,28–30]. …”

Section: Introductionmentioning

confidence: 99%

Difference equation model for isothermal gas chromatography expresses retention behavior of homologues of n-alkanes excluding the influence of holdup time

Chen

Caccamise

et al. 2012

Journal of Chromatography A

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Section: Introductionmentioning

confidence: 99%

“…Structural parameters that were used for such purposes span from a simple number of specific atoms to more elaborate calculated molecular properties (dipole moments, surfaces, energies, etc.). [5][6][7] Among these, a special position is taken by topological indices (Wiener, 8 Balaban,9 molecular topological indices, 10 etc.) which usually collectively, but not without limitations, take into account several molecular aspects (size, branching; i.e., connectivity) but are not easily related to a particular physicochemical property.…”

Section: Introductionmentioning

confidence: 99%

“…Allyl-3-methoxyphenyl tetradecanoate (3k): Yield: 60%; MS (EI), (m/z, (relative abundance, %)): 375(1), 374(M + , 5), 165(15), 164(BP, 100) [C 10 H 12 O 2 +], 149(7), 148(4), 137(5), 135(9), 133(3), 131(4), 103(3), 91(4), 77(3), 69(4), 57(10), 55(11), 43(17), 41(12), 39(2).46. 2-Allyl-3-methoxyphenyl hexadecanoate (3l): Yield: 56%; MS (EI), (m/z, (relative abundance, %)): 402(M + , 0.1), 166(3), 165(10), 164(BP, 100) [C 10 H 12 O 2 +], 149(7), 135(7), 131(3), 107(5), 81(6), 69(11), 57(4), 55(28), 54(4).47.…”

mentioning

confidence: 99%

“…69. 2-Allyl-6-methoxyphenyl formate (5a): Yield: 68%; MS (EI), (m/z, (relative abundance, %)): 193(2), 192(M + , 11), 165(11), 164(BP, 100) [C 10 H 12 O 2 +], 150(4), 149(43), 148(4), 147(10), 137(7), 135(7), 134(7), 133(15), 132(21), 131(48), 122(7), 121(42), 120(4), 119(4), 115(9), 107(6), 106(4), 105(15), 104(27), 103(59), 102(6), 94(6), 93(11), 92(8), 91(58), 89(7), 79(13), 78(17), 77(56), 66(10), 65(29), 64(6), 63(17), 62(6), 55(14), 53(10), 51(24), 50(10), 43(3), 41(6), 39(27), 38(5).…”

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A synthetic library of allylmethoxyphenyl esters: spectral characterization and gas chromatographic behavior

Mladenović

Radulović

2019

Flavour & Fragrance J

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A recent identification of eugenyl (allylmethoxyphenyl) esters as Anthemis segetalis Ten. (Asteraceae) essential oil constituents, accomplished by means of organic synthesis, motivated us to expand the existing synthetic library with an aim to examine the generality of structure‐chromatographic property relationships within this series of volatiles. Herein, the design, synthesis, gas–chromatographic and spectral characterization of members of a library of 85 allylmethoxyphenyl esters (64 are completely new) were described. Analysis of experimentally obtained RI data showed that esters of the same acid and different allylmethoxyphenols always elute in the same order from an apolar gas chromatography (DB‐5MS) column: 2‐allyl‐6‐methoxyphenyl < 2‐allyl‐3‐methoxyphenyl < 2‐allyl‐5‐methoxyphenyl < 2‐allyl‐4‐methoxyphenyl < 4‐allyl‐2‐methoxyphenyl esters. Based on the obtained RI values, several quantitative structure–property relationship models were built up that correlated several easily available parameters (e.g. Wiener [WI], Balaban [BI], and molecular topological [MTI] indices) of the mentioned esters and their RI data. The generated various quantitative structure–property relationships models (equations that predict RIs of esters of different regioisomers of allylmethoxyphenols with the same acids and the ones that predict RIs of esters of different acids with the same allylmethoxyphenols) were tested on data of previously known related esters. RI data of esters of allylmethoxyphenol regioisomers could be successfully predicted based on 1D topological indices, such as the Balaban, Wiener, and molecular topological indices. Together with RI and MS data accumulated in this work, these models represent a new and simple tool for the identification of allylmethoxyphenyl esters that might potentially represent new or rare natural products.

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Very‐Long‐Chain Wax Constituents from Primula veris and P. acaulis: Does the Paradigm of Non‐Branched vs. Branched Chain Dominance Universally Hold in all Plant Taxa?

Stošić

Radulović

Genčić

et al. 2021

Chemistry & Biodiversity

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Herein n-, iso-and anteiso-series of very-long-chained (VLC) alkanes (C 21 -C 35 ), fatty acid benzyl esters (FABEs; C 20 -C 32 ), and 2-alkanones (C 23 -C 35 ) were identified in the wax of Primula veris L. and P. acaulis (L.) L. (Primulaceae). For the very first time in a sample of natural origin, the presence of iso-and anteiso-VLC FABEs and 2-alkanones was unequivocally confirmed by synthetic work, derivatization, and NMR. It should be noted that the studied species produced unusually high amounts of branched wax constituents (e. g., > 50 % of 2alkanones were branched isomers). The domination of iso-isomers, probably biosynthesized from leucine-derived starters, is a unique feature in the Plant Kingdom. The plant organ distribution of these VLC compounds in P. acaulis samples (different habitats and phenological phases) pointed to their possible ecological value. This was supported by a eutectic behavior of binary blends of FABEs and alkanes, as well as by high UV-C absorption by FABEs.

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Prediction of retention indices. VI: Isothermal and temperature-programmed retention indices, methylene value, functionality constant, electronic and steric effects

Cited by 16 publications

References 23 publications

Difference equation model for isothermal gas chromatography expresses retention behavior of homologues of n-alkanes excluding the influence of holdup time

Difference equation model for isothermal gas chromatography expresses retention behavior of homologues of n-alkanes excluding the influence of holdup time

A synthetic library of allylmethoxyphenyl esters: spectral characterization and gas chromatographic behavior

Very‐Long‐Chain Wax Constituents from Primula veris and P. acaulis: Does the Paradigm of Non‐Branched vs. Branched Chain Dominance Universally Hold in all Plant Taxa?

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