Threshold Collision-Induced Dissociation of Hydrogen-Bonded Dimers of Carboxylic Acids

2008 ◽  
Vol 112 (8) ◽  
pp. 1773-1782 ◽  
Author(s):  
Beike Jia ◽  
Laurence A. Angel ◽  
Kent M. Ervin
1997 ◽  
Vol 436-437 ◽  
pp. 161-166 ◽  
Author(s):  
Alfred Kolbe ◽  
Monika Plass ◽  
Horst Kresse ◽  
Adelheid Kolbe ◽  
Jozef Drabowicz ◽  
...  

2003 ◽  
Vol 59 (1) ◽  
pp. 132-140 ◽  
Author(s):  
Henning Osholm Sørensen ◽  
Sine Larsen

The structural and thermodynamic backgrounds for the crystallization behaviour of racemates have been investigated using 2-phenoxypropionic acid (PPA) as an example. The racemate of PPA behaves normally and forms a racemic compound that has a higher melting point and is denser than the enantiomer. Low-temperature crystal structures of the pure enantiomer, the enantiomer cocrystallized with n-alkanes and the racemic acid showed that hydrogen-bonded dimers that form over crystallographic symmetry elements exist in all but the structure of the pure enantiomer. A database search for optically pure chiral mono-carboxylic acids revealed that the hydrogen-bonded cyclic dimer is the most prevalent hydrogen-bond motif in chiral mono-carboxylic acids. The conformation of PPA depends on the hydrogen-bond motif; the antiplanar conformation relative to the ether group is associated with a catemer hydrogen-bonding motif, whereas the more abundant synplanar conformation is found in crystals that contain cyclic dimers. Other intermolecular interactions that involve the substituent of the carboxylic group were identified in the crystals that contain the cyclic dimer. This result shows how important the nature of the substituent is for the crystal packing. The differences in crystal packing have been related to differences in melting enthalpy and entropy between the racemic and enantiomeric acids. In a comparison with the equivalent 2-(4-chlorophenoxy)-propionic acids, the differences between the crystal structures of the chloro and the unsubstituted acid have been identified and related to thermodynamic data.


2021 ◽  
pp. 122637
Author(s):  
Balamurugan Tharmalingam ◽  
Moorthy Mathivanan ◽  
Ottoor Anitha ◽  
Werner Kaminsky ◽  
Balasubramanian Murugesapandian

2014 ◽  
Vol 70 (3) ◽  
pp. 332-337 ◽  
Author(s):  
Carlos M. Sanabría ◽  
Alirio Palma ◽  
Justo Cobo ◽  
Christopher Glidewell

In the structure of (6R*,11R*)-5-acetyl-11-ethyl-6,11-dihydro-5H-dibenzo[b,e]azepine-6-carboxylic acid, C19H19NO3, (I), the molecules are linked into sheets by a combination of O—H...O and C—H...O hydrogen bonds; in the structure of the monomethyl analogue (6RS,11SR)-5-acetyl-11-ethyl-2-methyl-6,11-dihydro-5H-dibenzo[b,e]azepine-6-carboxylic acid, C20H21NO3, (II), the molecules are linked into simpleC(7) chains by O—H...O hydrogen bonds; and in the structure of the dimethyl analogue (6RS,11SR)-5-acetyl-11-ethyl-1,3-dimethyl-6,11-dihydro-5H-dibenzo[b,e]azepine-6-carboxylic acid, C21H23NO3, (III), a combination of O—H...O, C—H...O and C—H...π(arene) hydrogen bonds links the molecules into a three-dimensional framework structure. None of these structures exhibits theR22(8) dimer motif characteristic of simple carboxylic acids.


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