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Characterization of moisture-sensitive raw materials with simple spectroscopic techniques.
MedLine Citation:
PMID:  18970824     Owner:  NLM     Status:  In-Data-Review    
Abstract/OtherAbstract:
The quality of raw materials used in a synthetic process needs to be properly controlled in order to ensure optimal reaction conversion and desired quality of the resulting product. For air and water sensitive raw materials, quantitative analysis can be a challenging task. Spectroscopic techniques possess advantages of simple operation, fast analysis, low consumable costs and high sample throughput for the analysis of reactive raw materials. Three case studies utilizing spectroscopic analysis for air and water sensitive materials are discussed. First, FT-IR spectroscopy was utilized to determine the amount of residual acetic acid in acetic anhydride key raw material. Acetic anhydride was used in a methylenation reaction where the presence of residual acetic acid could quench a base used in the reaction, leading to incomplete conversion. A simple, one-frequency calibration method was developed to quantify acetic acid in acetic anhydride (2-35wt.%). Next, a novel near infrared reflectance spectroscopy (NIRS) method was used to determine the concentration of diisobutyl aluminum hydride (DIBAL-H) in toluene. DIBAL-H is a highly reactive and moisture-sensitive reagent used as a key raw material for the reduction of an active intermediate. A calibration method based on one-frequency was also developed to determine the concentration of DIBAL-H in toluene (0-1.5mole/L). Finally, a NIRS method based on partial least squares regression (PLS) was developed to quantify p-toluenesulfonic acid in p-toluenesulfonic anhydride, which is not amenable to chromatographic analysis.
Authors:
L Pan; R Lobrutto; G Zhou
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Publication Detail:
Type:  Journal Article     Date:  2006-04-27
Journal Detail:
Title:  Talanta     Volume:  70     ISSN:  1873-3573     ISO Abbreviation:  Talanta     Publication Date:  2006 Oct 
Date Detail:
Created Date:  2008-10-30     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  2984816R     Medline TA:  Talanta     Country:  England    
Other Details:
Languages:  eng     Pagination:  661-7     Citation Subset:  -    
Affiliation:
Merck and Co., Inc., Merck Research Laboratories, P.O. Box 2000, RY818-C306 Rahway, NJ 07065, USA.
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