3-(2-Acetylanilino)propanoic acid

The title molecule, C11H13NO3, has its propanoic acid group in an extended conformation, such that the molecule is nearly planar, with a mean deviation of 0.036 Å [the maxima being 0.106 (1) and 0.110 (1) Å for the two methylene C atoms]. The NH group forms an intramolecular hydrogen bond with the acetyl group; in the crystal COOH group forms a centrosymmetric hydrogen-bonded dimer.

The title molecule, C 11 H 13 NO 3 , has its propanoic acid group in an extended conformation, such that the molecule is nearly planar, with a mean deviation of 0.036 Å [the maxima being 0.106 (1) and 0.110 (1) Å for the two methylene C atoms]. The NH group forms an intramolecular hydrogen bond with the acetyl group; in the crystal COOH group forms a centrosymmetric hydrogen-bonded dimer.

Comment
Since the discovery that energy transfer from the triplet state of an organic ligand can efficiently sensitize the emissive states of metal ions (Crosby et al., 1961;1962) there has been considerable effort devoted to designing ligands that optimize this energy transfer and thus give efficient metal luminescence (Foley et al., 2003). The radiationless energy transfer photoluminescence and/or electro-luminescence properties of aromatic carbonyl compounds are strongly affected by the presence of a substituent on the aromatic ring. In general, the π, π * state is stabilized by introducing an electron-donating substituent on the aromatic ring, while the location of the n, π * state is only slightly modified by the electron-donating substituent. Thus, the fluorescence properties of the compounds with close-lying 1 (n, π * ) and 1 (π, π * ) states are expected to depend markedly on the nature of the solvent, such as its polarity and hydrogen-bonding ability. In 2'-aminoacetophenone, the 1 (n, π * ) and 1 (π, π * ) states are closely located in the lowest excited singlet state because of the presence of a strong electron-donating substituent. Owing to the proximity of two electronic levels, the photophysical properties of 2'-aminoacetophenone is very sensitive to environment, such as solvent polarity and temperature (Yoshihara et al., 2001). Therefore, the addition of a strong electron-donating substituent such as acrylic acid, which has the ability to form a solventless gel via hydrogen bonding, has been synthesized. The structure of the title compound, also known as 3-[(N-acetyl-phenyl)-azanediyl]-propionic acid, is herein described. Its synthesis takes advantage of the self-initiating condensation of 2'-aminoacetophenone with the vinyl group of the ab 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 developed (Walker, et al., 2004).

Experimental
A round bottom flask containing acrylic acid (1.051 g, 14.58 mmol) was stoppered and placed into the refrigerator overnight.
In a similar round bottom flask, 2'-aminoacetophenoneHCl (1.0056 g, 0.79199 g of liberated 2-aminoacetophenone 5.861 mmol) was dissolved in 10 ml of deionized water and chilled overnight. The round bottom flask containing the cold acrylic acid was then placed into to an ice bath to maintain a temperature of approximately 273 K. The ice bath was used because the reaction of acrylic acid and 2'-aminoacetophenone was thought to be exothermic. The cold 2'-aminoacetophenone solution was slowly added with stirring to the cold acrylic acid. The mixture was allowed to sit in the ice bath for 30 minutes and supplementary materials sup-2 then gradually warmed to room temperature, then kept at room temperature with continuous stirring overnight. A yellow precipitate was isolated by gravimetric filtration and washed with deionized water. The yellow solid material resulted in a yield of 0.8963 g (79.991%).

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 O were refined. U iso for H was assigned as 1.2 times U eq of the attached atoms (1.5 for methyl and OH). A torsional parameter was refined for the methyl group. Fig. 1. A view of the title compound; ellipsoids have been plotted at the 50% level and H atoms have been assigned arbitrary radii.  1, 176.7, 150.5, 135.2, 132.9, 117.9, 114.5, 111.3, 37.9, 33.8, and 27.9. 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 > σ(F 2 ) is used only for calculating Rfactors(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.