Crystal structure of morpholin-4-ium cinnamate

In the anhydrous salt formed from the reaction of morpholine with cinnamic acid, C4H10NO+·C9H7O2 −, the acid side chain in the trans-cinnamate anion is significantly rotated out of the benzene plane [C—C—C— C torsion angle = 158.54 (17)°]. In the crystal, one of the the aminium H atoms is involved in an asymmetric three-centre cation–anion N—H⋯(O,O′) R 1 2(4) hydrogen-bonding interaction with the two carboxylate O-atom acceptors of the anion. The second aminium-H atom forms an inter-species N—H⋯Ocarboxylate hydrogen bond. The result of the hydrogen bonding is the formation of a chain structure extending along [100]. Chains are linked by C—H⋯O interactions, forming a supramolecular layer parallel to (01-1).

In the anhydrous salt formed from the reaction of morpholine with cinnamic acid, C 4 H 10 NO + ÁC 9 H 7 O 2 À , the acid side chain in the trans-cinnamate anion is significantly rotated out of the benzene plane [C-C-C-C torsion angle = 158.54 (17) ]. In the crystal, one of the the aminium H atoms is involved in an asymmetric three-centre cation-anion N-HÁ Á Á(O,O 0 ) R 1 2 (4) hydrogen-bonding interaction with the two carboxylate O-atom acceptors of the anion. The second aminium-H atom forms an inter-species N-HÁ Á ÁO carboxylate hydrogen bond. The result of the hydrogen bonding is the formation of a chain structure extending along [100]. Chains are linked by C-HÁ Á ÁO interactions, forming a supramolecular layer parallel to (011).

S1. Comment
Morpholine (tetrahydro-2H-1,4-oxazine) forms salts with organic acids, and the crystal structures of a limited number of these with either aliphatic acids, e.g. the acetate (Kelley et al., 2013) or aromatic acids, e.g. the 4-nitrobenzoate (Chumakov et al., 2006), have been reported. With the salts of the aromatic acids, particularly those with non-associative substituent groups, cation-anion N-H···O carboxyl hydrogen-bonding interactions generate either one-dimensional chains or discrete cyclic heterotetrameric structures. In the present work, the title morpholinium salt of cinnamic acid, C 4 H 10 NO + C 9 H 7 O 2was prepared and its structure is reported herein.

S2. Experimental
The title compound was prepared by the dropwise addition of morpholine at room temperature to a solution of cinnamic acid (150 mg) in ethanol (10 ml). Room temperature evaporation of the solution gave an oil which was redissolved in ethanol, finally giving thin colourless plates of the title compound from which a specimen was cleaved for the X-ray analysis.

S3. Refinement
Hydrogen atoms were placed in calculated positions [C-H aromatic = 0.95 Å or C-H methylene = 0.99 Å] and were allowed to ride in the refinements, with U iso (H) = 1.2U eq (C). The aminium H atoms were located in a difference-Fourier analysis and were allowed to refine with distance restraints  The atom-numbering scheme and the molecular conformation of the morpholinium anion (B) and the cinnamate cation (A) in the title salt, with displacement ellipsoids drawn at the 40% probability level. The cation-anion hydrogen bonds are shown as dashed lines.

Figure 2
The one-dimensional hydrogen-bonded polymeric structure extending along a. For symmetry codes, see Table 1.

Morpholin-4-ium 3-phenylprop-2-enoate
Crystal data C 4 H 10 NO + ·C 9 H 7 O 2 − M r = 235.27 Triclinic, P1 Hall symbol: -P 1 a = 5.7365 (7) Å b = 9.7526 (10) Å c = 11.7760 (11) Å α = 103.270 (8) where P = (F o 2 + 2F c 2 )/3 (Δ/σ) max < 0.001 Δρ max = 0.15 e Å −3 Δρ min = −0.15 e Å −3 Special details Geometry. Bond distances, angles etc. have been calculated using the rounded fractional coordinates. All su's are estimated from the variances of the (full) variance-covariance matrix. The cell esds are taken into account in the estimation of distances, angles and torsion angles Refinement. Refinement of F 2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F 2 , conventional R-factors R are based on F, with F set to zero for negative F 2 . The threshold expression of F 2 > 2sigma(F 2 ) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F 2 are statistically about twice as large as those based on F, and R-factors based on ALL data will be even larger.