L-Glutamic acid hydrochloride at 153 K

Abstract

The title compound [systematic name: (S)-1,3-dicarboxy­propanaminium chloride], C5H10NO4 +·Cl−, has been investigated previously by Dawson [Acta Cryst. (1953). 6, 81–83], with R = 0.106 and without the location of H atoms, and then by Sequeira, Rajagopal & Chidambaram [Acta Cryst. (1972). B28, 2514–2519] using neutron diffraction with R = 0.043. The present determination at 153 K has R = 0.017 and all the H atoms are located. There are obvious differences in some C—C bond lengths between the present and previous studies. In the present structure, l-glutamic acid is protonated and is linked to the Cl− anion by an O—H⋯Cl hydrogen bond. The crystal structure is established by a three-dimensional network of O—H⋯O, N—H⋯O and N—H⋯Cl hydrogen bonds.

EPR and FT-IR spectroscopic studies of l-lysine monohydrochloride and l-glutamic acid hydrochloride powders

“…In the structure of LMHCl lysine is present in the form of singly charged cation, in which amino groups are protonated owing to carboxyl group and HCl acid, i.e., + H 3 NA(CH 2 ) 4 ACH(NH þ 3 )COO À ÁCl À [31][32][33]. Following this idea, in the structure of LGAHCl the glutamic acid is present in the form of singly charged cation, in which amino groups are protonated owing to HCl acid, i.e., HOOCA(CH 2 ) 2 A CH(NH þ 3 ÁCl À )ACOOH [34]. For the LMHCl: Stretching vibrations of NAH bonds in the IR spectra are revealed as bands at 3128 cm À1 and a shoulder at 3047 cm À1 , which is overlapped with strong band in the region of stretching vibrations of CAH bonds.…”

Crystal structures of amino acids: from bond lengths in glycine to metal complexes and high-pressure polymorphs

“…In fact, only a few amino acids have been crystallized in three different states, and Glu is the only one that has been crystallized in four, Figure 6. [68][69][70][71] In addition to the regular protonation states shown in Figure 4, there is also an intermediate state where two amino acids, usually in the c(1) and z(0) states, form a strong -COOH· · · − OOChydrogen bond and share a total charge of +1. This surprisingly large group of 57 structures will here be simply referred to as 'Speakman salts' [72] and is discussed in Section 10.…”