Comparison of in-line NIR, Raman and UV-visible spectrometries, and at-line NMR spectrometry for the monitoring of an esterification reaction

C A McGill, A Nordon, D Littlejohn

Research output: Contribution to journalArticle

36 Citations (Scopus)

Abstract

In-line Raman, near infrared and UV-visible spectometries, and at-line low-field NMR spectrometry have been used to monitor the acid-catalysed esterification of crotonic acid and butan-2-ol. Repeat reactions were carried out in a 1 L batch reactor. Spectra taken during the reactions, along with reference ester concentrations determined by gas chromatography (GC), were used to determine the concentration of 2-butyl crotonate as the reaction proceeded. Ester concentrations were determined from 1st derivative Raman and UV-visible spectra by employing univariate calibration models, whereas the low-field NMR and NIR data required multivariate analysis by partial least squares regression. The techniques have been compared on the basis of the accuracy and between-run precision of the 2-butyl crotonate concentrations, and the ability to determine the rate constant of the reaction in the shortest possible time after the start of the reaction. The ester concentrations determined by all of the techniques were similar to those obtained by the GC reference method. In-line UV-visible spectrometry gave the poorest between-run precision. Raman and NIR spectrometries provided an estimate of the rate constant of the reaction after 90 min when the ester concentration had reached 0.09 mol dm(-3), meaning that if the rate constant at this time was not as expected then corrective action could be taken to salvage the batch.

LanguageEnglish
Pages287-292
Number of pages6
JournalAnalyst
Volume127
Issue number2
DOIs
Publication statusPublished - 2002

Fingerprint

Esterification
Spectrometry
ester
spectrometry
nuclear magnetic resonance
Spectrum Analysis
Esters
Crotonates
Nuclear magnetic resonance
Rate constants
Monitoring
monitoring
Gas chromatography
Gas Chromatography
gas chromatography
Salvaging
visible spectrum
Acids
acid
Batch reactors

Keywords

  • near-infrared spectroscopy
  • catalyzed esterification
  • acetic-acid
  • emulsion polymerization
  • ethanol
  • probe

Cite this

@article{5b332f7262ba4f9e9f8dd1826335ba91,
title = "Comparison of in-line NIR, Raman and UV-visible spectrometries, and at-line NMR spectrometry for the monitoring of an esterification reaction",
abstract = "In-line Raman, near infrared and UV-visible spectometries, and at-line low-field NMR spectrometry have been used to monitor the acid-catalysed esterification of crotonic acid and butan-2-ol. Repeat reactions were carried out in a 1 L batch reactor. Spectra taken during the reactions, along with reference ester concentrations determined by gas chromatography (GC), were used to determine the concentration of 2-butyl crotonate as the reaction proceeded. Ester concentrations were determined from 1st derivative Raman and UV-visible spectra by employing univariate calibration models, whereas the low-field NMR and NIR data required multivariate analysis by partial least squares regression. The techniques have been compared on the basis of the accuracy and between-run precision of the 2-butyl crotonate concentrations, and the ability to determine the rate constant of the reaction in the shortest possible time after the start of the reaction. The ester concentrations determined by all of the techniques were similar to those obtained by the GC reference method. In-line UV-visible spectrometry gave the poorest between-run precision. Raman and NIR spectrometries provided an estimate of the rate constant of the reaction after 90 min when the ester concentration had reached 0.09 mol dm(-3), meaning that if the rate constant at this time was not as expected then corrective action could be taken to salvage the batch.",
keywords = "near-infrared spectroscopy, catalyzed esterification, acetic-acid, emulsion polymerization, ethanol, probe",
author = "McGill, {C A} and A Nordon and D Littlejohn",
year = "2002",
doi = "10.1039/B106889J",
language = "English",
volume = "127",
pages = "287--292",
journal = "Analyst",
issn = "0003-2654",
number = "2",

}

TY - JOUR

T1 - Comparison of in-line NIR, Raman and UV-visible spectrometries, and at-line NMR spectrometry for the monitoring of an esterification reaction

AU - McGill, C A

AU - Nordon, A

AU - Littlejohn, D

PY - 2002

Y1 - 2002

N2 - In-line Raman, near infrared and UV-visible spectometries, and at-line low-field NMR spectrometry have been used to monitor the acid-catalysed esterification of crotonic acid and butan-2-ol. Repeat reactions were carried out in a 1 L batch reactor. Spectra taken during the reactions, along with reference ester concentrations determined by gas chromatography (GC), were used to determine the concentration of 2-butyl crotonate as the reaction proceeded. Ester concentrations were determined from 1st derivative Raman and UV-visible spectra by employing univariate calibration models, whereas the low-field NMR and NIR data required multivariate analysis by partial least squares regression. The techniques have been compared on the basis of the accuracy and between-run precision of the 2-butyl crotonate concentrations, and the ability to determine the rate constant of the reaction in the shortest possible time after the start of the reaction. The ester concentrations determined by all of the techniques were similar to those obtained by the GC reference method. In-line UV-visible spectrometry gave the poorest between-run precision. Raman and NIR spectrometries provided an estimate of the rate constant of the reaction after 90 min when the ester concentration had reached 0.09 mol dm(-3), meaning that if the rate constant at this time was not as expected then corrective action could be taken to salvage the batch.

AB - In-line Raman, near infrared and UV-visible spectometries, and at-line low-field NMR spectrometry have been used to monitor the acid-catalysed esterification of crotonic acid and butan-2-ol. Repeat reactions were carried out in a 1 L batch reactor. Spectra taken during the reactions, along with reference ester concentrations determined by gas chromatography (GC), were used to determine the concentration of 2-butyl crotonate as the reaction proceeded. Ester concentrations were determined from 1st derivative Raman and UV-visible spectra by employing univariate calibration models, whereas the low-field NMR and NIR data required multivariate analysis by partial least squares regression. The techniques have been compared on the basis of the accuracy and between-run precision of the 2-butyl crotonate concentrations, and the ability to determine the rate constant of the reaction in the shortest possible time after the start of the reaction. The ester concentrations determined by all of the techniques were similar to those obtained by the GC reference method. In-line UV-visible spectrometry gave the poorest between-run precision. Raman and NIR spectrometries provided an estimate of the rate constant of the reaction after 90 min when the ester concentration had reached 0.09 mol dm(-3), meaning that if the rate constant at this time was not as expected then corrective action could be taken to salvage the batch.

KW - near-infrared spectroscopy

KW - catalyzed esterification

KW - acetic-acid

KW - emulsion polymerization

KW - ethanol

KW - probe

U2 - 10.1039/B106889J

DO - 10.1039/B106889J

M3 - Article

VL - 127

SP - 287

EP - 292

JO - Analyst

T2 - Analyst

JF - Analyst

SN - 0003-2654

IS - 2

ER -