Symbiosis between computation and experiment is increasingly evident in pedagogic journals such as J. Chemical Education. Thus an example of original laboratory experiments[cite]10.1021/ed077p271[/cite],[cite]10.1021/ed078p1266[/cite] that later became twinned with a computational counterpart.[cite]10.1021/ed500398e[/cite] So when I spotted this recent lab experiment[cite]10.1021/acs.jchemed.7b00566[/cite] I felt another twinning approaching.
Posts Tagged ‘Functional groups’
Organocatalytic cyclopropanation of an enal: (computational) mechanistic understanding.
Saturday, August 25th, 2018Are diazomethanes hypervalent molecules? An attempt into more insight by more “tuning” with substituents.
Tuesday, December 26th, 2017Recollect the suggestion that diazomethane has hypervalent character[cite]10.1039/C5SC02076J[/cite]. When I looked into this, I came to the conclusion that it probably was mildly hypervalent, but on carbon and not nitrogen. Here I try some variations with substituents to see what light if any this casts.
π-Facial hydrogen bonds to alkynes (revisited): how close can an acidic hydrogen approach?
Monday, April 17th, 2017Following on from my re-investigation of close hydrogen bonding contacts to the π-face of alkenes, here now is an updated scan for H-bonds to alkynes. The search query (dataDOI: 10.14469/hpc/2478) is similar to the previous one:
The conformation of carboxylic acids revealed.
Tuesday, April 11th, 2017Following my conformational exploration of enols, here is one about a much more common molecule, a carboxylic acid.
σ or π nucleophilic reactivity of imines? A mechanistic reality check using substituents.
Sunday, October 9th, 2016Previously, a mechanistic twist to the oxidation of imines using peracid had emerged. Time to see how substituents respond to this mechanism.
σ or π nucleophilic reactivity of imines? A mechanistic twist emerges.
Wednesday, September 28th, 2016The story so far. Imines react with a peracid to form either a nitrone (σ-nucleophile) or an oxaziridine (π-nucleophile).[cite]10.1016/S0040-4039(00)98582-4[/cite] The balance between the two is on an experimental knife-edge, being strongly influenced by substituents on the imine. Modelling these reactions using the “normal” mechanism for peracid oxidation did not reproduce this knife-edge, with ΔΔG (π-σ) 16.2 kcal/mol being rather too far from a fine balance.
More stereoelectronics galore: hexamethylene triperoxide diamine.
Thursday, September 22nd, 2016Compounds with O-O bonds often have weird properties. For example, artemisinin, which has some fascinating stereoelectronics. Here is another such, recently in the news and known as HMTD (hexamethylene triperoxide diamine). The crystal structure was reported some time ago[cite]10.1021/jp0123841[/cite] and the article included an inspection of the computed wavefunction. However this did not look at the potential stereoelectronics in this species, which I now address here.
How does an OH or NH group approach an aromatic ring to hydrogen bond with its π-face?
Wednesday, June 22nd, 2016I previously used data mining of crystal structures to explore the directing influence of substituents on aromatic and heteroaromatic rings. Here I explore, quite literally, a different angle to the hydrogen bonding interactions between a benzene ring and OH or NH groups.