Isovaline monohydrate

Abstract

Key indicators: single-crystal X-ray study; T = 123 K; mean (C-C) = 0.005 Å; R factor = 0.056; wR factor = 0.162; data-to-parameter ratio = 13.2.The title compound, C 5 H 11 NO 2 ÁH 2 O, is an isomer of theamino acid valine that crystallizes from water in its zwitterion form as a monohydrate. It is not one of the 20 proteinogenic amino acids that are used in living systems and differs from the natural amino acids in that it has no -H atom. The compound exhibits hydrogen bonding between the water molecule and the carboxylate O atoms and an amine H atom. In addition, there are intermolecular hydrogen-bonding interactions between the carboxylate O atoms and amine H atoms. In the crystal, these extensive N-HÁ Á ÁO and O-HÁ Á ÁO hydrogen bonds lead to the formation of a three-dimensional network.

(S)-2-Azaniumyl-2-methyl-3-phenylpropanoate monohydrate

“…23239-35-2 for the non-hydrated molecule), the molecule has a conformation like a cross, in which the propylbenzene group has a trans conformation [torsion angle C10-C2-C3-C4: = 167.9 (2) ]. A similar conformation is found in other 2-methyl-substituted amino acids, for example, isoVal monohydrate, CISNUP [ = 177.0 (3) ; Butcher et al, 2013] and DMTYRS [ = À176.58 (1) ], while the cis conformation is observed in other cases, as in QABCAX. This slightly distorted data reports conformation is also comparable to that found in the crystal structures of phenylalanine derivatives, for example in l-Phe monohydrate (GOFWOP; Williams et al, 2013).…”

1-Azaniumylcyclobutane-1-carboxylate monohydrate

“…For the mechanism of racemization of amino acids lacking an -H atom, see: Pizzarello & Groy (2011). For the role that crystallization can play in the enrichment of l-isovaline and its structure, see: Butcher et al (2013). For normal bond lengths and angles, see: Orpen (1993).…”

“…For normal bond lengths and angles, see: Orpen (1993). For the hydrochloride salt of the title compound and related non-proteinogenic amino acids, see: Chacko & Zand (1975); Butcher et al (2013); Brewer et al (2013). For conformational studies on model proteins with 1-aminocyclobutane-1-carboxylic acid residues, see: Balaji et al (1995).…”

2-Methylaspartic acid monohydrate

“…We recently reported the structure of another non-proteinogenic amino acid, isovaline, which crystallized as a racemic conglomerate from water in contrast to the present example which crystallizes in a centrosymmetric space group and is thus a racemate as indicated above (Butcher et al, 2013). Resolved 2-methylaspartic acid and the structure given here can be used as a starting point in mechanistic studies of racemization mechanisms of amino acids lacking an alpha hydrogen atom.…”

“…For the mechanism of racemization of amino acids lacking an -H atom, see : Pizzarello & Groy (2011). For the role that crystallization can play in the enrichment of l isovaline and its structure, see: Glavin & Dworkin (2009);Butcher et al (2013). For normal bond lengths and angles, see: Orpen (1993).…”