2-Amino-1-(2-carboxylatoethyl)pyrimidin-1-ium monohydrate

In the title structure, C7H9N3O2·H2O, there are two formula units in the asymmetric unit. The molecule is a zwitterion, containing a quaternary N atom and a deprotonated carboxyl group, with C—O distances in the range 1.256 (2)–1.266 (3) Å. The two independent molecules form a hydrogen-bonded R 2 2(16) dimer about an approximate inversion center via N—H⋯O hydrogen bonds, with N⋯O distances of 2.766 (2) and 2.888 (2) Å. O—H⋯O hydrogen bonds involving the water molecules and additional N—H⋯O hydrogen bonds link these dimers, forming double chains.

In the title structure, C 7 H 9 N 3 O 2 ÁH 2 O, there are two formula units in the asymmetric unit. The molecule is a zwitterion, containing a quaternary N atom and a deprotonated carboxyl group, with C-O distances in the range 1.256 (2)-1.266 (3) Å . The two independent molecules form a hydrogen-bonded R 2 2 (16) dimer about an approximate inversion center via N-HÁ Á ÁO hydrogen bonds, with NÁ Á ÁO distances of 2.766 (2) and 2.888 (2) Å . O-HÁ Á ÁO hydrogen bonds involving the water molecules and additional N-HÁ Á ÁO hydrogen bonds link these dimers, forming double chains.

Comment
With the growing environmental awareness of the global economy, there has been an increased interest in "green" solvents.
Since ionic liquids or ionic solvents are considered nonvolatile substances with negligible vapor pressure, they can be utilized in establishing novel "green" synthetic routes (Santos et al., 2007). Deep eutectic solvents (DES) are considered a designated group within the broad range of ionic solvents, more specifically, they are a type of ionic solvent with special properties composed of a mixture that forms a eutectic with a melting point much lower than either of the individual components.
The first generation eutectic solvents were based on mixtures of quaternary ammonium salts with hydrogen donors such as amines and carboxylic acids. The deep eutectic solvent concept was first described by Abbot et al. (2003Abbot et al. ( , 2004 for a mixture of choline chloride and urea. The mixture resulted in a eutectic that melts at 285 K. DES are capable of dissolving many metal salts. Since the solvents are conductive, DES have a potential application as battery electrolytes. Compared to ionic liquids, deep eutectic solvents are cheaper to make, much less toxic, and are sometimes biodegradable. Production of 3-(2-aminopyrimidin-1-yl) propanoate by quaternerization of the amine within the aromatic system presents a new molecular construct for deep eutectic solvents. DES can be modified in order to control factors such as conductivity, viscosity, and surface tension (Reddy, 2006). The synthesis of of 3-(2-aminopyrimidin-1-yl) propanoate takes advantage of the self-initiating condensation of 2-aminopyrimidine with the vinyl group of the αβ-unsaturated acrylic acid via anti-Markovnikov addition, which is similar to chemistry involved in the synthesis of the novel 3,3',3"-nitrilotripropionic acid precursor gel, that we have recently developed (Walker et al., 2004).
The asymmetric unit of the title compound, consisting of two 2-aminopyrimidinium carboxylate molecules and two water molecules, is shown in Fig. 1. The two main molecules form a hydrogen-bonded dimer of graph set (Etter, 1990) R 2 2 (16) about an approximate inversion center located near 0.186, 0.632, 0.281. The carboxyl group is deprotonated, as evidenced by all C-O distances falling within a narrow range 1.256 (2) (Holy et al., 1999;Slouf et al., 2002).
supplementary materials sup-2 Experimental 2-Aminopyrimidine (1.001 g, 10.52 mmol) was dissolved in 10 ml deionized water. The solution was charged with acrylic acid (1.5 ml, 21.9 mmol) and refluxed at 343-348 K for 2 h. After heating, the mixture was stirred continuously until the temperature gradually cooled to room temperature (299 K). A light yellow aqueous slurry was obtained. In a 125 ml separatory funnel, the aqueous slurry was combined with 15 ml of benzene and shaken for several minutes. The aqueous layer was isolated and filtered. The resulting white crystalline material product was isolated by gravimetric filtration, washed with three 20 ml aliquots of cold ethanol, and allowed to air-dry overnight, yielding 1.217 g (69.36%) of white solid material.

Refinement
H atoms on C were placed in idealized positions with C-H distances 0.95 -0.99 Å and thereafter treated as riding. Coordinates for the H atoms on N and H 2 O were refined. U iso for H was assigned as 1.2 times U eq of the attached atoms (1.5 for methyl and H 2 O). Fig. 1. The asymmetric unit, with ellipsoids at the 50% level and H atoms having arbitrary radius. Dotted lines are hydrogen bonds.