Chiral para-alkyl phenyl ethers of glycerol: synthesis and testing of chirality driven crystallization, liquid crystal, and gelating properties

A series of enantiopure and racemic p-alkylphenyl glycerol ethers 1a–k were synthesized. A new, sensitive, and pictorial method of comparison of the IR spectra of solid enantiopure and racemic samples was developed to obtain preliminary information on the crystallization types of these compounds. In order to detect the subtle differences in the organization of the chiral solid phase, a new easily implemented approach, based on a chromatographic measuring of the relative abundance of the enantiomers in a single solution in equilibrium with a solid sample of arbitrary (0 < ee < 1) composition, is reported. One new conglomerate compound (Alk = n-Pr) and one borderline case (Alk = n-Bu) are disclosed. Higher members of the series of 1 (starting with an n-Bu derivative) are turned into liquid crystals upon melting; no significant differences between racemic and non-racemic samples were found. Only enantiopure methyl-, n-butyl, n-pentyl, n-hexyl, and n-heptyl substituted 1 were able to form supramolecular gels in hydrocarbon solvents; all racemic ethers 1 did not show such ability.

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(S)-3-(4-Methylphenoxy)-propane-1,2-diolC10H14O3ee = 99.0% (ee from HPLC)[α]D20=+9.1 (c 0.8, EtOH)Initial source of chirality: AD-mix-βAbsolute configuration: (S)

(S)-3-(4-Ethylphenoxy)-propane-1,2-diolC11H16O3ee = 99.5% (ee from HPLC)[α]D20=+6.7 (c 1.2, EtOH)Initial source of chirality: AD-mix-βAbsolute configuration: (S)

(S)-3-(4-Isopropylphenoxy)-propane-1,2-diolC12H18O3ee = 99.0% (ee from HPLC)[α]D20=+6.7 (c 1.0, EtOH)Initial source of chirality: AD-mix-βAbsolute configuration: (S)

(S)-3-(4-n-Propylphenoxy)-propane-1,2-diolC12H18O3ee = 99.7% (ee from HPLC)[α]D20=+7.2 (c 1.0, EtOH)[α]D20=+7.3 (c 0.98, MeOH)Initial source of chirality: AD-mix-βAbsolute configuration: (S)

(S)-3-(4-tert-Butylphenoxy)-propane-1,2-diolC13H20O3ee = 91.0% (ee from HPLC)[α]D20=+6.6 (c 1.0, EtOH)[α]D20=+6.2 (c 0.6, MeOH)Initial source of chirality: AD-mix-βAbsolute configuration: (S)

(S)-3-(4-n-Butylphenoxy)-propane-1,2-diolC13H20O3ee = 99.9% (ee from HPLC)[α]D20=+6.6 (c 1.0, EtOH)Initial source of chirality: AD-mix-βAbsolute configuration: (S)

(S)-3-(4-n-Pentylphenoxy)-propane-1,2-diolC14H22O3ee = 99.6% (ee from HPLC)[α]D20=+7.6 (c 1.0, EtOH)Initial source of chirality: AD-mix-βAbsolute configuration: (S)

(S)-3-(4-n-Hexylphenoxy)-propane-1,2-diolC15H24O3ee = 99.1% (ee from HPLC)[α]D20=+6.4 (c 1.0, EtOH)Initial source of chirality: AD-mix-βAbsolute configuration: (S)

(S)-3-(4-n-Heptylphenoxy)-propane-1,2-diolC16H26O3ee = 99.7% (ee from HPLC)[α]D20=+6.5 (c 1.0, EtOH)Initial source of chirality: AD-mix-βAbsolute configuration: (S)

(S)-3-(4-n-Octylphenoxy)-propane-1,2-diolC17H28O3ee = 99.7% (ee from HPLC)[α]D20=+5.8 (c 1.0, MeOH)Initial source of chirality: AD-mix-βAbsolute configuration: (S)

(S)-3-(4-n-Nonylphenoxy)-propane-1,2-diolC18H30O3ee = 99.2% (ee from HPLC)[α]D20=+5.3 (c 0.5, MeOH)Initial source of chirality: AD-mix-βAbsolute configuration: (S)