| dc.contributor.author | McMahon, Kevin. | en_US |
| dc.date.accessioned | 2014-10-21T12:38:28Z | |
| dc.date.available | 1991 | |
| dc.date.issued | 1991 | en_US |
| dc.identifier.other | AAINN71541 | en_US |
| dc.identifier.uri | http://hdl.handle.net/10222/55282 | |
| dc.description | The photochemical nucleophile-olefin combination, aromatic substitution (photo-NOCAS) reaction is a potentially useful synthetic procedure. Readily available starting materials (a nucleophile, an olefin, and an aromatic molecule) are combined to make a more complex bifunctional product in one simple step; two new bonds are made during the process. The utility of this procedure for the synthesis of para-cyanophenyl $\beta$-alkyl ethers has been amply demonstrated, and a mechanism has been proposed which is consistent with all of the observations. The reaction has been shown to be fairly general with respect to the olefin: both acyclic and cyclic olefins react regio- and stereoselectively, to give primarily the anti-Markovnikov products. Until now no study has been undertaken to examine the role and diversity of the electron accepting aromatics. | en_US |
| dc.description | Previous work has emphasised 1,4- and 1,2-dicyanobenzene as the electron accepting aromatic reactant. While the para- or ortho-cyano group incorporated in the product is a useful functionality for further synthetic modification, for many applications it will be desirable to have some other functional group. Consideration of the mechanism leads to the suggestion that the reaction may incorporate other electron withdrawing substituted aromatic molecules. A series of para-substituted benzonitriles (para = $\rm Co\sb2CH\sb3\ ({\bf 22})$, $\rm -SO\sb2CH\sb3\ ({\bf 58})$, $\rm -F\ ({\bf 59})$, $\rm -CF\sb3\ ({\bf 60})$, $\rm -N(CH\sb3)\sb3I\ ({\bf 61}$), $\rm -COH\ ({\bf 68})$, and $-$COPh (69)) was examined and the results will be discussed. | en_US |
| dc.description | When an acetonitrile-methanol solution of methyl 4-cyanobenzene (22) and 2,3-dimethyl-2-butene (2) is irradiated in the presence of added co-donor biphenyl (12), three 1:1:1 (methanol: olefin: aromatic) adducts are formed. However, when the irradiation is repeated in the absence of 12, only one 1:1 (olefin: aromatic) adduct, a cyclic imine (23), is obtained (83%). No such imine formation has been observed using 1,4-dicyanobenzene (1) as an electron acceptor, and there are few examples of this type of photochemical reaction. The singlet lifetime of (22) has been estimated in this study ($\tau\sb{s} < 2 ns).$ The apparent reactivity from the singlet excited state of 22 has been explained in terms of an excited charge transfer complex. Ultraviolet absorption studies confirm the existence of a ground state association between the acceptor and olefin 2. | en_US |
| dc.description | The reactivity of all the acceptors (except 69) involves photochemically induced electron transfer (PET). Observations can be rationalised in terms of the electrochemical behaviour, and calculated (ab initio and semi-empirical) spin and charge densities of the intermediate radical-anions. The mechanism, originally proposed for reactions involving 1, has been extended to explain the observations from this study. | en_US |
| dc.description | Thesis (Ph.D.)--Dalhousie University (Canada), 1991. | en_US |
| dc.language | eng | en_US |
| dc.publisher | Dalhousie University | en_US |
| dc.publisher | | en_US |
| dc.subject | Chemistry, Organic. | en_US |
| dc.title | The photochemical nucleophile-olefin combination, aromatic substitution (photo-NOCAS) reaction. The scope of the reaction with respect to the aromatic electron acceptor. | en_US |
| dc.type | text | en_US |
| dc.contributor.degree | Ph.D. | en_US |
