Crystal structure of (R,S)-2-hy-droxy-4-(methyl-sulfan-yl)butanoic acid.

Thomas P Mawhinney,Deborah L Chance,Steven P Kelley,Valeri V Mossine,Yiyi Li

doi:10.1107/s2056989020003138

Thomas P Mawhinney, Deborah L Chance + Show 3 more

Open Access

https://doi.org/10.1107/s2056989020003138

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Abstract

The title compound, a major animal feed supplement, abbreviated as HMTBA and alternatively called dl-me-thio-nine hy-droxy analogue, C5H10O3S, (I), was isolated in pure anhydrous monomeric form. The melting point is 302.5 K and the compound crystallizes in the monoclinic space group P21/c, with two conformationally non-equivalent mol-ecules [(I A ) and (I B )] in the asymmetric unit. The crystal structure is formed by alternating polar and non-polar layers running along the bc plane and features an extensive hydrogen-bonding network within the polar layers. The Hirshfeld surface analysis revealed a significant contribution of non-polar H⋯H and H⋯S inter-actions to the packing forces for both mol-ecules.

Highlights

The title compound, a major animal feed supplement, abbreviated as HMTBA and alternatively called dl-methionine hydroxy analogue, C5H10O3S, (I), was isolated in pure anhydrous monomeric form
-Hydroxy carboxylic acids are indispensable players in plant and animal metabolism, and many of these substances are commercially important chemicals, because of their wide use in chemical industries and as pharmaceuticals, skin-care agents, or nutritional supplements (Bhalla et al, 2013). 2-Hydroxy-4-(methylsulfanyl)butanoic acid (I) is a natural precursor in methionine biosynthesis, and, for decades, synthetic HMTBA has been used on an industrial scale as a supplement to animal feeds in order to boost methionine production, in farmed poultry (Zhang et al, 2015)
Metal salts provide a means for stabilization of the -hydroxy carboxylate monomers, and structures of two HMTBA metal salts, Cu[(R,S)HMTBA]2 (CCDC 1018852; Yang et al, 2015) and Zn[(R,S)HMTBA]2 (CCDC 671417; Predieri et al, 2009), have been solved by X-ray diffraction

Summary

Chemical context

-Hydroxy carboxylic acids are indispensable players in plant and animal metabolism, and many of these substances are commercially important chemicals, because of their wide use in chemical industries and as pharmaceuticals, skin-care agents, or nutritional supplements (Bhalla et al, 2013). 2-Hydroxy-4-(methylsulfanyl)butanoic acid (I) is a natural precursor in methionine biosynthesis, and, for decades, synthetic HMTBA has been used on an industrial scale as a supplement to animal feeds in order to boost methionine production, in farmed poultry (Zhang et al, 2015). In the crystal of (R,S)-HMTBA copper salt (Yang et al, 2015), a similar (t, t, g+) backbone rotamer exists in the (S)HMTBA molecule. A similar spatial arrangement of the O1 and O3 atoms was reported in the aforementioned copper and zinc salts of HMTBA (Table 1), where simultaneous coordination of the carboxylate and hydroxyl oxygen atoms to the metal ions provided for the formation of nearly flat fivemembered chelate rings (Yang et al, 2015; Predieri et al, 2009). In crystal structures of the simplest -hydroxy carboxylic acids, glycolic acid (CCDC 1169248; Pijper, 1971) and l(+)-lactic acid (CCDC 1303177; Schouten et al, 1994), the molecular fragments including non-hydrogen atoms of the hydroxyl and carboxyl groups are nearly flat (Table 1). (Gorbitz et al, 2014) (Alagar et al, 2005) (Schouten et al, 1994) (Pijper, 1971)

Supramolecular features

Database survey

Synthesis and crystallization

Findings

Refinement