Formation of the N-Iodopyridinium Cation in an Alkane Environment: Mid-Infrared Linear Dichroism Investigation of the Pyridine-Iodine System in Stretched Polyethylene

Publikation: Bidrag til bog/antologi/rapportKonferenceabstrakt i proceedingsForskning

Resumé

It is well known that pyridine (py) and iodine (I2) form a 1:1 molecular complex, py-I2. Within the framework of a student project at Roskilde University [1], we have recently investigated the formation and mid-infrared linear dichroism of the complex in a stretched polyethylene (PE) matrix. However, the observed spectra displayed not only the expected transitions due to py and py-I2, but also a third, prominent series of sharp transitions, evidently due to one or more additional products. On the basis of a comparison with literature spectra, we assigned these transitions to the N-iodopyridinium cation (pyI+). This assignment is consistent with the observed polarization data. Ionic side reactions (py-I2 = pyI+ + I–, py-I2 + I2 = pyI+ + I3–, etc.) are easily observed in binary pyridine-iodine mictures and in polar solvents, but not so easily in non-polar media. We are thus surprised to see the apparent efficiency with which the pyI+ cation is formed in an apolar and aprotic medium like PE. With excess iodine, the peaks assigned to pyI+ dominate the observed mid-infrared spectrum. We suspect that a driving force for the ionic reaction is the formation of polyiodide anions in the channels of the polymer medium. Further investigation of the phenomenon is in progress. [1] H. S. van Deurs, M. L. M. Espersen, R. Nissen, M. H. Rasmussen, C. J. S. Schönbeck, Student Project, Roskilde University, June 2006 (in Danish).
OriginalsprogEngelsk
TitelXVIII International Conference on Physical Organic Chemistry : ICPOC-18, August 20-25, 2006
RedaktørerM. K. Cyranski, K. Wozniak, T. M. Krygowski
Antal sider2
ForlagInternational Union of Pure and Applied Chemistry
Publikationsdato2006
Sider42-43
ISBN (Trykt)83-89585-11-1
StatusUdgivet - 2006
BegivenhedInternational Conference on Physical Organic Chemistry (ICPOC) - Warszawa, Polen
Varighed: 20 aug. 200625 aug. 2006
Konferencens nummer: 18

Konference

KonferenceInternational Conference on Physical Organic Chemistry (ICPOC)
Nummer18
LandPolen
ByWarszawa
Periode20/08/200625/08/2006

Citer dette

Spanget-Larsen, J. (2006). Formation of the N-Iodopyridinium Cation in an Alkane Environment: Mid-Infrared Linear Dichroism Investigation of the Pyridine-Iodine System in Stretched Polyethylene. I M. K. Cyranski, K. Wozniak, & T. M. Krygowski (red.), XVIII International Conference on Physical Organic Chemistry: ICPOC-18, August 20-25, 2006 (s. 42-43). International Union of Pure and Applied Chemistry.
Spanget-Larsen, Jens. / Formation of the N-Iodopyridinium Cation in an Alkane Environment : Mid-Infrared Linear Dichroism Investigation of the Pyridine-Iodine System in Stretched Polyethylene. XVIII International Conference on Physical Organic Chemistry: ICPOC-18, August 20-25, 2006. red. / M. K. Cyranski ; K. Wozniak ; T. M. Krygowski. International Union of Pure and Applied Chemistry, 2006. s. 42-43
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abstract = "It is well known that pyridine (py) and iodine (I2) form a 1:1 molecular complex, py-I2. Within the framework of a student project at Roskilde University [1], we have recently investigated the formation and mid-infrared linear dichroism of the complex in a stretched polyethylene (PE) matrix. However, the observed spectra displayed not only the expected transitions due to py and py-I2, but also a third, prominent series of sharp transitions, evidently due to one or more additional products. On the basis of a comparison with literature spectra, we assigned these transitions to the N-iodopyridinium cation (pyI+). This assignment is consistent with the observed polarization data. Ionic side reactions (py-I2 = pyI+ + I–, py-I2 + I2 = pyI+ + I3–, etc.) are easily observed in binary pyridine-iodine mictures and in polar solvents, but not so easily in non-polar media. We are thus surprised to see the apparent efficiency with which the pyI+ cation is formed in an apolar and aprotic medium like PE. With excess iodine, the peaks assigned to pyI+ dominate the observed mid-infrared spectrum. We suspect that a driving force for the ionic reaction is the formation of polyiodide anions in the channels of the polymer medium. Further investigation of the phenomenon is in progress. [1] H. S. van Deurs, M. L. M. Espersen, R. Nissen, M. H. Rasmussen, C. J. S. Sch{\"o}nbeck, Student Project, Roskilde University, June 2006 (in Danish).",
author = "Jens Spanget-Larsen",
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Spanget-Larsen, J 2006, Formation of the N-Iodopyridinium Cation in an Alkane Environment: Mid-Infrared Linear Dichroism Investigation of the Pyridine-Iodine System in Stretched Polyethylene. i MK Cyranski, K Wozniak & TM Krygowski (red), XVIII International Conference on Physical Organic Chemistry: ICPOC-18, August 20-25, 2006. International Union of Pure and Applied Chemistry, s. 42-43, International Conference on Physical Organic Chemistry (ICPOC), Warszawa, Polen, 20/08/2006.

Formation of the N-Iodopyridinium Cation in an Alkane Environment : Mid-Infrared Linear Dichroism Investigation of the Pyridine-Iodine System in Stretched Polyethylene. / Spanget-Larsen, Jens.

XVIII International Conference on Physical Organic Chemistry: ICPOC-18, August 20-25, 2006. red. / M. K. Cyranski; K. Wozniak; T. M. Krygowski. International Union of Pure and Applied Chemistry, 2006. s. 42-43.

Publikation: Bidrag til bog/antologi/rapportKonferenceabstrakt i proceedingsForskning

TY - ABST

T1 - Formation of the N-Iodopyridinium Cation in an Alkane Environment

T2 - Mid-Infrared Linear Dichroism Investigation of the Pyridine-Iodine System in Stretched Polyethylene

AU - Spanget-Larsen, Jens

PY - 2006

Y1 - 2006

N2 - It is well known that pyridine (py) and iodine (I2) form a 1:1 molecular complex, py-I2. Within the framework of a student project at Roskilde University [1], we have recently investigated the formation and mid-infrared linear dichroism of the complex in a stretched polyethylene (PE) matrix. However, the observed spectra displayed not only the expected transitions due to py and py-I2, but also a third, prominent series of sharp transitions, evidently due to one or more additional products. On the basis of a comparison with literature spectra, we assigned these transitions to the N-iodopyridinium cation (pyI+). This assignment is consistent with the observed polarization data. Ionic side reactions (py-I2 = pyI+ + I–, py-I2 + I2 = pyI+ + I3–, etc.) are easily observed in binary pyridine-iodine mictures and in polar solvents, but not so easily in non-polar media. We are thus surprised to see the apparent efficiency with which the pyI+ cation is formed in an apolar and aprotic medium like PE. With excess iodine, the peaks assigned to pyI+ dominate the observed mid-infrared spectrum. We suspect that a driving force for the ionic reaction is the formation of polyiodide anions in the channels of the polymer medium. Further investigation of the phenomenon is in progress. [1] H. S. van Deurs, M. L. M. Espersen, R. Nissen, M. H. Rasmussen, C. J. S. Schönbeck, Student Project, Roskilde University, June 2006 (in Danish).

AB - It is well known that pyridine (py) and iodine (I2) form a 1:1 molecular complex, py-I2. Within the framework of a student project at Roskilde University [1], we have recently investigated the formation and mid-infrared linear dichroism of the complex in a stretched polyethylene (PE) matrix. However, the observed spectra displayed not only the expected transitions due to py and py-I2, but also a third, prominent series of sharp transitions, evidently due to one or more additional products. On the basis of a comparison with literature spectra, we assigned these transitions to the N-iodopyridinium cation (pyI+). This assignment is consistent with the observed polarization data. Ionic side reactions (py-I2 = pyI+ + I–, py-I2 + I2 = pyI+ + I3–, etc.) are easily observed in binary pyridine-iodine mictures and in polar solvents, but not so easily in non-polar media. We are thus surprised to see the apparent efficiency with which the pyI+ cation is formed in an apolar and aprotic medium like PE. With excess iodine, the peaks assigned to pyI+ dominate the observed mid-infrared spectrum. We suspect that a driving force for the ionic reaction is the formation of polyiodide anions in the channels of the polymer medium. Further investigation of the phenomenon is in progress. [1] H. S. van Deurs, M. L. M. Espersen, R. Nissen, M. H. Rasmussen, C. J. S. Schönbeck, Student Project, Roskilde University, June 2006 (in Danish).

M3 - Conference abstract in proceedings

SN - 83-89585-11-1

SP - 42

EP - 43

BT - XVIII International Conference on Physical Organic Chemistry

A2 - Cyranski, M. K.

A2 - Wozniak, K.

A2 - Krygowski, T. M.

PB - International Union of Pure and Applied Chemistry

ER -

Spanget-Larsen J. Formation of the N-Iodopyridinium Cation in an Alkane Environment: Mid-Infrared Linear Dichroism Investigation of the Pyridine-Iodine System in Stretched Polyethylene. I Cyranski MK, Wozniak K, Krygowski TM, red., XVIII International Conference on Physical Organic Chemistry: ICPOC-18, August 20-25, 2006. International Union of Pure and Applied Chemistry. 2006. s. 42-43