Lactone-size identification of D-ribonolactone derivatives has been debated for four decades due to complex lactone-ring rearrangements and acetal migration. This laboratory experiment for an upper-division undergraduate organic chemistry laboratory course describes a fast and reliable assignment of lactone-size derivatives from D-ribose using 1 H and 1 H− 1 H NOESY NMR spectroscopy. In addition, the further derivatization of these lactones via O-acylation is described, followed by a theoretical study that allows conformational analysis of these molecules in solution using JANOCCHIO software. Overall, this experiment uses simple, inexpensive, and commercially available reagents, and the reactions are performed in mild conditions. The products are solid and can be either purified by crystallization or used directly in the next step of the synthesis. 13 C, 2D 1 H− 1 H COSY, and 1 H− 13 C HMQC or HSQC spectra are also analyzed. Therefore, this laboratory experiment allows students to explore several NMR techniques and relate them with basic NMR concepts, such as scalar coupling constants related to dihedral angles and the NOE effect, to predict lactone-size and conformation of the synthesized molecules in solution.

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Polar‐terminated 3,5‐diarylisoxazole liquid crystals (ILCs) were synthetized and characterized. ILCs are composed by rigid core 3,5‐diarylisoxazol, alkyl chain and polar‐terminated flexible spacer. Hydroxyl‐, ketal‐ and 1,2‐diol‐terminated ILCs rendered smectic C and A mesophase, while bromine‐terminated ILCs showed smectic A and B mesophase, for monosubstituted and linear ILCs. For branched alkyl chain monotropic SmA was detected and for disubstituted ILCs no mesophase was detected. Out‐of‐layer fluctuations (OLFs) are discussed based on X‐ray diffraction date and textures. The OLFs are dependent on the bromine atom hardness, hydrogen bonding through collective actions and conformational effects at the interface between layers. Smectic translational order parameter (TOP) Σ was also obtained for orientated bromine‐ and hydroxyl‐terminated ILCs and related it with OLFs. For 1,2‐diol‐terminated ILCs two SmC sublayers were founded, probably related to the intramolecular hydrogen bond favoring the 5‐membered and 6‐membered formation.