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2-Bromobutane is chiral

  • The rotational spectra of 2-bromobutane were obtained by using a chirped-pulse Fouriertransform microwave (CP-FTMW) spectrometer in the frequency range 8–18 GHz.
    Hyperfine structures of both bromine isotopologues (I = 3/2) for the three conformers (G+,
    A, and G&minushave been investigated to determine the rotational constants, centrifugal
    distortion constants, and nuclear quadrupole coupling constants of bromine (Br).
    However, the small zero-point energy
    differences of isotopomers can be negligible and can be considered as an average value
    instead of individual values, which is 54%, 30%, 16% for G+, A, and G− species. The
    nuclear quadrupole coupling tensors (χxx, χyy, and χzz) of Br and the quadrupolar angles were
    obtained, and the χzz value of 2-bromobutane is compared with those of other alkyl bromides.
    The spectroscopic constants, rs coordinates of Br and the dipole moments of the most stable
    Rotational spectra of 2-bromobutane were measured using a CP-FTMW spectroscopy.
     Hyperfine structures for 79Br and 81Br species of G+, A, and G− conformers were assigned.
     Relative abundances of conformers were estimated by relative intensity measurements.
     Spectroscopic constants and structural parameters were compared to ab initio calculations.
     Dipole moments of the G+ conformer were determined by the Stark effect measurements.
    Conformational analyses of 2-halobutanes have previously been conducted by using infrared (IR) spectroscopy [1–5], Raman spectroscopy [6,7], microwave spectroscopy [8], electron diffraction analysis [9–11], and theoretical calculations [12,13]. In this paper, according to the dihedral angle of the Br-C2-C3-C4 bonds, the three conformers of 2-bromobutane are labeled as A (anti), G+, and G− (gauche), corresponding to dihedral angles of ~180°, +60°,and −60°, respectively (Fig. 1).
    2-Bromobutane is an organobromide compound. Bromine is a halogen element with the symbol Br and atomic number 35. Diatomic bromine does not occur naturally, but bromine salts can be found in crustal rock.
    A chemical structure of a molecule includes the arrangement of atoms and the chemical bonds that hold the atoms together. The 2-Bromobutane molecule contains a total of 13 bond(s). There are 4 non-H bond(s) and 1 rotatable bond(s). Images of the chemical structure of 2-Bromobutane are given below:
    2-Bromobutane is an isomer of 1-bromobutane. Both compounds share the molecular formula C4H9Br. 2-Bromobutane is also known as sec-butyl bromide or methylethylbromomethane. Because it contains bromine, a halogen, it is part of a larger class of compounds known as alkyl halides. It is a colorless liquid with a pleasant odor. Because the carbon atom connected to the bromine is connected to two other carbons the molecule is referred to as a secondary alkyl halide. 2-Bromobutane is chiral and thus can be obtained as either of two enantiomers designated as-(−)-2-bromobutane and-(+)-2-bromobutane.
    Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

    2-Bromobutane is relatively stable, but is toxic and flammable. When treated with a strong base, it is prone to undergo an E2 reaction, which is a bimolecular elimination reaction, resulting in (predominantly) 2-butene, an alkene (double bond). 2-Bromobutane is an irritant, and harmful if ingested. It can irritate and burn skin and eyes