A structure-reactivity study of selected phosphate esters

A comparative X-ray analysis study of bis(4-nitrophenyl)-8-quinolinyl phosphate (4), 1-naphthyl-bis(4-nitrophenyl) phosphate (5) and 4-nitrophenyl -8-quinolinyl phosphate (5) was undertaken. In compound (4) donor-acceptor nitrogen-phosphorus interactions change the geometry of the molecule from tetrahedral to quasi trigonal bipyramidal, thus the structure may be considered as an "early stage" of the intramolecular displacement of the 4-ni trophenoxide group. In the diester (6) this interaction is replaced by intermolecular N+ -H...O- hydrogen bonding. In addition the intramolecular non-bonded potential energies of (4) and (5) were calculated and the minimum-energy conformations were compared with those determined by X-ray diffraction. These results confirm the differences observed in the intramolecular interactions operative in (4) and (5). The mass spectra of (4) and (5) are dramatically different with respect to the fragmentation involving expulsion of the 4-nitrophenoxy radical and formation of the corresponding phosphorylitum ion by nitrogen participation. Rate measurements for the base-catalysed hydrolysis of the first P-OPNP linkage show that (4) is not significantly more reactive than (5) and provide no evidence for intramolecular nucleophilic catalysis in the hydrolysis of (4). The crystal and molecular structure of 1-naphthyl acetate (7) was determined. Attempts to grow suitable crystals of 8-quinolinyl acetate (8) failed and therefore its structure could not be elucidated. Possible intramolecular nitrogen - carbonyl carbon interactions operative in (8) could therefore not be established.

Grantor dc:publisher.institution

Department of Chemistry

Year dc:date.issued

1985

Author dc:creator

• Bond, Dianne Ruth

Advisor dc:contributor.advisor

• Nassimbeni, Luigi R

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/11427/22521

OAI identifier oai:identifier

oai:open.uct.ac.za:11427/22521