Reaction Mechanism between the cyclic Sulfonylimine, (N-Isocyanoimino)triphenylphosphorane, and Benzoic Acid

This page makes use of JSmol to render molecules as an intractable object. This package has two modes: HTML5, and WEBGL. The first is slower and produces a lower quality rendering, but supports showing vibrations and is supported on more devices. Therefore, it has been chosen as the default rendering mode. To reload the page with WEBGL, click here, but note that all animations will be disabled.

It may take a few minutes for all of the components to load, so be patient! Note that Chrome and similar browsers will not respond until the page is fully loaded, so do not be alarmed if the page does not respond Intermediately! You can tell the page has finished loaded when benzene is displayed below:

If Web-based applications are too slow, please download the Gaussian16 output files and formatted checkpoint files, which are provided as links on this webpage and on the associated GitHub profile.

The Mechanism is divided into the following parts:

Starting material Interactions Transition States Intermediates Products

Starting Material

Below is the starting materials for the reaction. When summed together, the total ΔG is 0 as these reactants serve as the reference state for all other steps in the reaction.

Starting Sulfonylimine (Gaussian output and checkpoint)

Fullscreen HTML5 WEBGL

Benzoic Acid (Gaussian output and checkpoint)

Fullscreen HTML5 WEBGL

(N-Isocyanoimino)triphenylphosphorane (Gaussian output and checkpoint)

Fullscreen HTML5 WEBGL

Interactions between reactants

These are interaction structures formed between the reactants before a transition state can be formed.

Interaction between the starting material and (N-Isocyanoimino)triphenylphosphorane (Gaussian output and checkpoint)

Fullscreen HTML5 WEBGL

Interaction between intermediate 1 and benzoic acid (Gaussian output and checkpoint)

Fullscreen HTML5 WEBGL

Transition States

Below are the four transition states for the reaction shown in an interactive JSmol applet. By default, the sole negative frequency is shown, but this can be turned off using the toggle links below the animation. Additional vibrations can be loaded by right clicking the application and selecting a different model.

Attack of (N-Isocyanoimino)triphenylphosphorane onto the Sulfonylimine

Vibration: On Off

Gaussian output and checkpoint

Fullscreen HTML5 WEBGL

Attack of the Carboxylic acid onto Intermediate-1

Vibration: On Off

Gaussian output and checkpoint

Fullscreen HTML5 WEBGL

Ring closing step

Vibration: On Off

Gaussian output and checkpoint

Fullscreen HTML5 WEBGL

Removal of Ph3P=0

Vibration: On Off

Gaussian output and checkpoint

Fullscreen HTML5 WEBGL

Intermediate States

Below are the intermediates for the reaction.

Intermediate 1 (Gaussian output and checkpoint)

Fullscreen HTML5 WEBGL

Intermediate 2 (Gaussian output and checkpoint)

Fullscreen HTML5 WEBGL

Intermediate 3 (Gaussian output and checkpoint)

Fullscreen HTML5 WEBGL

Oxazaphosphetidine Intermediate (Gaussian output and checkpoint)

Fullscreen HTML5 WEBGL

Products

The products of the reaction are an oxadiazole and Ph3P=O.

The resulting oxadiazole (Gaussian output and checkpoint)

Fullscreen HTML5 WEBGL

Ph3P=O (Gaussian output and checkpoint)

Fullscreen HTML5 WEBGL