Organo-Iodine Compounds Analysis by the 5975-SMB GC-MS with Cold EI

Aviv Amirav, Professor of Chemistry at Tel Aviv University and Director - Aviv Analytical

Larisa Panz Ph.D., Ksenia Kulbitski and Professor Mark Gendelman, Schulich Faculty of Chemistry at the Technion Haifa Israel. 

Introduction

Organo-iodine compounds are used in several applications, mostly as intermediates in organic synthesis because of the easy formation and cleavage of the C–I bond. The analysis of organo-iodine compounds is highly challenging since most of them are not compatible with LC-MS and electrospray ionization while in GC-MS their analysis is hampered via their possible decomposition at the GC injector, column and ion source since the iodine-carbon bond is by far the weakest among all halogen-carbon bonds. Furthermore, even if the organo-iodine compounds elute from the GC column their standard EI mass spectra are often void of any molecular ions and as a result their identification becomes impossible. Motivated by the above challenges we explored the analysis of novel synthetic organo-iodine compounds with the Aviv Analytical 5975-SMB GC-MS with Cold EI, developed a method for its successful analysis and compared the results with that obtained with GC-MS with standard EI.

Keep reading to find out how the Aviv Analytical 5975-SMB GC-MS with Cold EI uniquely enables the effective analysis of synthetic organo-iodine compounds and provides unambiguous identification of all the synthetic organo-iodine reaction mixture compounds and as a result helps optimizing the synthesis reaction conditions and yields.

Organic Chemical Reaction Yields Optimization by GC-MS with Cold EI and Walk-by GC-FID

Aviv Amirav, School of Chemistry, Tel Aviv University and Director – Aviv Analytical 

Tal Sela and Arkadi Vigalok, School of Chemistry, Tel Aviv University.  

Introduction

Chemical reactions are typically followed by lengthy and tedious products separation and purification for their identification by NMR and high resolution mass spectrometry (such as with QTOF). However, with this procedure no information is obtained about the synthesis yield, products purity, availability of isomers and on the reaction mechanism, since the already-purified compounds are analyzed and since ESI has non-uniform, highly compound dependent ionization yields. 

In order to enable semi-on-line monitoring and optimization of organic chemical reactions we used the Aviv Analytical 5975-SMB GC-MS with Cold EI as described in a previous post in the blog. The 5975-SMB GC-MS with Cold EI (EI of cold molecules in supersonic molecular beams) was used with reaction mixtures without their prior separation and purification as required for NMR analysis, thereby saving time and effort. GC-MS with Cold EI was demonstrated to significantly extend the range of compounds amenable for analysis, practically always giving molecular ions, enabling effective fast GC-MS analysis and providing elemental formulas via isotope abundance analysis with unit mass resolution quadrupole MS. In addition, it uniquely provides uniform response to all compounds, a feature which is vital for the measurement of chemical reaction yields. 

We are aware of the fact that a system of this kind is typically placed in a separate laboratory and operated by a dedicated operator thus may not be fully available for the simultaneous repetitive monitoring of several reactions. Our goal is to convert the concept of semi-on-line reaction monitoring for its optimization into a widely used concept and technology that is shared and used by students and non-expert analytical chemists. As a result, we refined and further improved the concept of reaction monitoring by the 5975-SMB GC-MS with Cold EI to be followed by the use of a walk-by GC-FID for enabling frequent semi-on-line monitoring of the reactions by the organic chemistry students. Accordingly, the 5975-SMB provides the identification of all the reaction mixture components and their order of elution and elution times while the GC-FID can have the same column, column flow rate and other related method parameters and later serve for the quantitation of the reaction products and for its optimization.       

Keep reading to find out how the Aviv Analytical 5975-SMB GC-MS with Cold EI followed by a standard GC-FID can change the way organic synthesis is performed. 

Measurement and Optimization of Organic Chemical Reaction Yields by GC-MS with Cold EI

Aviv Amirav, School of Chemistry, Tel Aviv University and Director – Aviv Analytical 

Alexander Gordin, Bogdan Belgorodsky, Boaz Seemann, Michael Gozin and Alexander B. Fialkov, School of Chemistry, Tel Aviv University.  

Introduction

Chemical reactions are typically involved with mixing the reactants together in an appropriate solvent, often with addition of a catalyst, and allowing them to undergo a reaction, which may take from couple of minutes to few days. The progress of the reaction is either assumed or monitored most-commonly by thin layer chromatography. However, little or no information is obtained on-line on the reaction actual progress and its yield. At the perceived end of the reaction, the products are separated and purified by preparative chromatography, distillation, sublimation, selective precipitation or crystallization, processes which may take several hours or even several days. Subsequently, the purified products are analyzed by 1H and 13C NMR and by high resolution mass spectrometry (often Quadrupole Time of Flight (QTOF) mass spectrometer), typically via flow injection electrospray ionization (FI-ESI). Yet, while FI-ESI-QTOF provides elemental formulas information, it does not provide information about the synthesis yield, products purity, availability of isomers and on the reaction mechanism, since the already-purified compounds are analyzed and since ESI has non-uniform, highly compound dependent ionization yields. 

In order to alleviate the above mentioned shortcomings of organic synthesis, we used the Aviv Analytical 5975-SMB GC-MS with Cold EI for semi-on-line monitoring of organic chemical reactions for obtaining information on the reaction products identity and purity and for mechanism elucidation and reaction yield optimization. The 5975-SMB was used with reaction mixtures without their prior separation and purification as required for NMR analysis, thereby saving time and effort. Our unique 5975-SMB GC-MS with Cold EI is based on GC interface with the MS with supersonic molecular beams (SMB) and on the ionization of the sample molecules during their axial flight through an open electron ionization ion source as vibrationally cold molecules (hence the name Cold EI). GC-MS with Cold EI was demonstrated to significantly extend the range of compounds amenable for analysis, practically always giving molecular ions, enabling effective fast GC-MS analysis and providing elemental formulas via isotope abundance analysis with unit mass resolution quadrupole MS. In addition, it uniquely provides uniform response to all compounds, a feature which is vital for the measurement of chemical reaction yields. 

Keep reading to find out how the Aviv Analytical 5975-SMB GC-MS with Cold EI can change the way organic synthesis is performed via enabling semi on-line monitoring of the progress of organic reactions and via the provision of information on the reaction mechanism, products identity and purity and the chemical reaction yield for its optimization. 

Tetryl Analysis using the 5975-SMB GC-MS with Cold EI

Aviv Amirav, Professor of Chemistry at Tel Aviv University and Director - Aviv Analytical Ltd

Introduction

Tetryl, (2,4,6-Trinitrophenylmethylnitramine, C7H5N5O8) is a sensitive explosive compound used to make detonators and explosive booster charges. Tetryl is produced by slowly mixing dimethylaniline with concentrated nitric acid in the presence of sulfuric acid and due to its simple synthesis it is prone for attempted synthesis by terrorists. Tetryl is a thermally labile explosives that is known to be difficult to analyze by GC-MS due to its degradation at the GC injector and at the GC column to N-methylpicramide through a loss of NO and a gain of hydrogen from the column PDMS film. As a result, the analysis of Tetryl is challenging. 

   

We received a sample of Tetryl that was synthesized by A.I. Explosives, Inspection & Services Company (www.aiexplosives.com) that attempted to follow terrorist's synthetic roots and characterize it via the tetryl synthetic impurities.   

In this post we present the uniquely successful analysis of Tetryl perform with Aviv Analytical's 5975-SMB GC-MS.