# Impact of Reactant Dissolution in the Kinetics of a Catalytic Hydrogenation for the Production of Argatroban

## TL;DR

This study examines how reactant dissolution affects the hydrogenation process for making Argatroban, showing how temperature, stirring, and catalyst loading influence reaction efficiency and accuracy of measurements.

## Contribution

The paper introduces a refined first-principles model that incorporates catalyst effects on dissolution and improves prediction accuracy.

## Key findings

- Increasing temperature from 40 to 80 °C reduced batch time by 58% but increased impurities.
- Catalyst loading significantly affects reagent dissolution rate and batch time.
- A refined model incorporating dissolution mass transfer improved prediction accuracy of reaction kinetics.

## Abstract

An experimental study was performed for a fed-batch catalytic
hydrogenation
for the production of Argatroban. The penultimate expensive and scarcely
available intermediate is characterized by a slow dissolution rate
that evolves in parallel with the reaction process. The study investigated
the coupling between the reaction and dissolution kinetics. In these
circumstances, the standard Area Percentage method in HPLC was found
to be misleading, requiring calibration and then absolute peak area
measurements to correctly identify the dissolution rate and thus the
actual chemical kinetics. Experiments quantified the role of the temperature,
stirring rate, and catalyst loading. Shifting from 40 to 80 °C
reduced the batch time by 58%, although higher temperatures promoted
the formation of undesired impurities. Stirring rate controlled the
initial reaction phases when reagent dissolution is critical. Catalyst
loading is key in reducing batch time. The increase in catalyst loading
was proved to affect the reagent dissolution rate, by increasing the
collision frequency between reagent and catalyst particles. A refined
first-principles model, incorporating the effect of the catalyst amount
on the dissolution mass transfer coefficient, significantly improved
the accuracy of dissolution predictions and enabled better identification
of the intrinsic reaction kinetics. The addition of a microkinetic
description further improved the predictions of intermediates and
products.