facile microwave synthesis and study of catalytic properties

Charles McElroy IVInorganic and Environmental Research

Facile Microwave Synthesis and Study of Catalytic Properties of

Cobalt(II)Porphyrazinyl Compounds

2

OverviewOne-Pot microwave synthesis of Cobalt(II) and other transition

metal porphyrazines

Disulfide Bridging by auto-oxidation using the following catalystsCo(II)-PhthalocyanineCo(II)-2,3-pyridinoporphyrazineCo(II)-3,4-pyridinoporphyrazineCo(II)-pyrazinylporphyrazine

Relative kinetics of each catalyst used

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Reaction time is extensive, nearly five to six hours of intense heat and pressure

Extraction methods are complicated involving dilution with a strong acid and neutralization and precipitation with a strong base

Phthalocyanine compounds are vulnerable to mobility of the metal cation, reducing efficiency as a catalyst over time

Traditional Methods and Materials

Proposed Methods and MaterialsSynthesis reaction time is less than five minutes with the use of microwaves and

no other source of heat or pressureSynthesized porphyrazine catalysts prove to be soluble in most protic solventsAddition of larger external functional groups stabilize metal cationMicrowave heating affects the reactants directly allowing to overcome the

activation energy easily.

[1] B.N. Achar, G.M. Fohlen, J.A. Parker, and J. Keshavaya. Polyhedron. Vol 6 no. 6. 1463-1467. 1987.

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Cobalt (II) Porphyrazines IUPAC: Tetrabenzoporphyrazine Insoluble in water and most organic solvents. Traditionally used in catalyst beds for auto-oxidation of

thiols in crude oil refinement Strengthened by reducing mobility of the metal cation

Cobalt(II)Phthalocyanine

[2] Löbbert, G. "Phthalocyanines" in Ullmann's Encyclopedia of Industrial Chemistry, 2002, Wiley-VCH, Weinheim. doi: 10.1002/14356007.a20_213.

Use outside of catalysis Pharma – has been studied extensively as a target

tracer molecule in oncology Biosensors and Electrodes – replaces the commonly

used carbon paste electrode for various applications of chemical sensors in bioanalytical chemistry

Commercially important as nearly 25% of all organic pigments are metal phthalocyanine derivatives

http://en.wikipedia.org/wiki/Digital_object_identifier

http://dx.doi.org/10.1002/14356007.a20_213

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MEROX (Mercapto-oxidation)

[4] Sullivan, D. The Role of the Merox Process in the Era of Low Sulfur Transportation Fuels. 5th EMEA Catalyst Technology Conference. 3,4 March 2004.

Microwave Synthesis2,3-pyp

3,4-pyp

2,3-prz

phth

6[3] Ki Suck Jung, Jong Ho Kwon, Se Mo Shon, Jun Phil Ko, Jun Sik Shin, Seong Soo Park. Journal of Materials Science. Vol 39. 723-726. 2004.

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Cobalt(II)Imidazoylporphyrazine

Cobalt(II)-imidazoleporphyrazine

Soluble in polar and non-polar solventsPossibility of crystallization under certain

conditionsPure phthalocyanine forms quasi-crystals,

polymorphs. Not good for x-ray diffraction characterization.

Less likely to decompose under protonated environments as 2,3-pyp and 3,4-pyp do.

Less likely to solvate in basic environments like pyrazinoporphyrazine does.

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Synthesis of and standard and functionalized imidazole dicarboxylic acid

Cobalt(II)Imidazoylporphyrazine

[6] U.S. Patent #3852292-1 “2-(PYRIDYL)-IMIDAZOLE-4,5,-DICARBOXYLIC ACID AND DERIVATIVES[7] U.S. Patent #4550176-1 “PREPARATION OF IMIDAZOLE DICARBOXYLIC ACID”

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Tested with all catalysts Pentanethiol and octanethiol had best results Tert-nonanethiol was good for phthalocyanine and IMP but not others

Auto-oxidation of Thiols

Table 1- Taken from Co(II)-phthalocyanine 20min reactions.

MM Density BP Vol (μL) Conv %104.2 0.848 116.5 31 25.56104.2 0.840 126 31 30.28102.2 0.955 130 27 61.29116.2 0.950 159 31 46.21146.3 0.843 180 43 86.55160.3 0.842 220 48 50.78174.4 0.841 241 52 81.25202.4 0.845 274 60 <1

Thiol NamePHTH Conversion

tertnonanethioldecanethiol

nonanethiol

2-methylbutanethiol3-methylbutanethiol

pentanethiolcyclohexylthiol

octanethiol

[5] I. Chatti, A. Ghorbel, P. Grange, J.M. Colin. Catalysis Today. Vol 75. 113-117. 2002.

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GC-MS Analysis - PRZ Mix 5minoctanol

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GC-FID Analysis - IMP Octanethiol 5min

octanol

octanethiol

octanedisulfide

Octanethiol - 5 MinutesPeak# Ret Time Peak Type Width Area Height Area %

1 2.051637 PP 0.015321 1.786185 1.840757 0.002746

2 2.092994 VB S 0.044167 60665.04 23776.36 93.2518

3 2.204053 BB X 0.050581 19.57739 6.450805 0.030094

4 5.33101 PB 0.01872 2.588276 2.169278 0.003979

5 5.601031 PB 0.019137 2.850645 2.319708 0.004382

6 5.952922 BB 0.02506 2295.204 1434.977 3.528093

7 6.078688 BB 0.020507 5.244357 4.104505 0.008061

8 6.180302 PP 0.016056 1.234719 1.279746 0.001898

9 6.463738 BB 0.021293 1590.945 1182.737 2.445536

10 6.908894 BP 0.054894 440.2234 100.9153 0.676693

11 7.358114 BB 0.020259 1.8159 1.370441 0.002791

12 7.527458 BB 0.018897 2.200984 1.821506 0.003383

13 9.234859 BB 0.036827 9.783592 4.072518 0.015039

14 10.57492 BB 0.023187 9.525361 6.318651 0.014642

15 10.83251 BP 0.024271 2.209983 1.44275 0.003397

16 10.94914 BBA 0.03259 4.85816 2.304913 0.007468

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Conversion of Thiols (2,3-pyp and 3,4-pyp)

Time Conv % Time Conv % Time Conv %5 min 9.52 5 min 66.05 5 min 43.82

10 min 19.35 10 min 70.1 10 min 8115 min 29.23 15 min 72.15 15 min 82.4720 min 30.91 20 min 74.38 20 min 88.8825 min 35.56 25 min 75 25 min 97.0530 min 71.06 30 min 76.29 30 min 98.44

Cobalt(II)-2,3-pyridinoporphyrazine2-ethylhexanethiolMixed ThiolsCyclopentanethiol

5 10 15 20 25 300

20

40

60

80

100

Cobalt(II)-2,3-pyridino-porphyrazine

Pentanethiol Mixed Thiols Octanethiol

Time (Minutes)

Perc

ent

Con

vers

ion

5 10 15 20 25 300

20

40

60

80

100

Cobalt(II)-3,4-pyridino-porphyrazine

Pentanethiol Mixed Thiols Octanethiol

Time (Minutes)

Perc

ent

Con

vers

ion


10 min 19.35 10 min 70.1 10 min 8115 min 29.23 15 min 72.15 15 min 82.4720 min 30.91 20 min 74.38 20 min 88.8825 min 35.56 25 min 75 25 min 97.0530 min 71.06 30 min 76.29 30 min 98.44

Cobalt(II)-2,3-pyridinoporphyrazineOctanethiolMixed ThiolsPentanethiol


10 min 26.7 10 min 61.02 10 min 92.5915 min 38.57 15 min 64.29 15 min 92.5920 min 55 20 min 81.52 20 min 93.125 min 55.3 25 min 83.33 25 min 96.9730 min 58.7 30 min 87.3 30 min 98.01

Mixed Thiols OctanethiolCobalt(II)-3,4-pyridinoporphyrazine

Pentanethiol

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Conversion of Thiols (2,3-prz and phth)Time Conv % Time Conv % Time Conv %5 min 21.15 5 min 29.47 5 min 27.44

10 min 35.42 10 min 31.55 10 min 32.6515 min 40.96 15 min 46.42 15 min 41.5620 min 45.7 20 min 54.61 20 min 55.9725 min 59.83 25 min 66.21 25 min 56.2830 min 60.13 30 min 69.22 30 min 70.72

Cobalt(II)-2,3-pyrazinoporphyrazineCyclopentanethiol Mixed Thiols 2-ethylhexanethiol



Cobalt(II)-phthalocyanineCyclopentanethiol Mixed Thiols 2-ethylhexanethiol

5 10 15 20 25 300

20

40

60

80

100

Cobalt(II)-2,3-pyrazino-porphyrazine

Mixed Thiols Pentanethiol Octanethiol

Time (Minutes)

Perc

ent

Con

vers

ion

5 10 15 20 25 300

20

40

60

80

100

Cobalt(II)-phthalocyanine Mixed Thiols Pentanethiol Octanethiol

Time (Minutes)

Perc

ent

Con

vers

ion



Cobalt(II)-phthalocyaninePentanethiol Mixed Thiols Octanethiol



Cobalt(II)-2,3-pyrazinoporphyrazinePentanethiol Mixed Thiols Octanethiol

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Conversion of Thiols (IMP)

5 10 15 20 25 300

20

40

60

80

100

COBALT(II)IMIDAZOYLPORPHYRAZINEPentanethiol Octanethiol Mixed Thiols

Time (MINUTES)

PER

CE

NT

CO

NV

ER

SIO

N Pentanethiol Mixed Octanethiol5 30.75 39.48 35.6310 48.89 40.95 58.6715 70.02 47.28 78.5820 82.20 59.08 83.5225 89.67 73.35 87.6030 91.55 100.0 99.59

Co(II)Imidazoylporphyrazine

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DiscussionThe characterization of the catalyst was only performed qualitatively through

observance of the catalytic properties expected. Proper characterization could be further performed most likely through FTIR

analysis, NMR analysis, and even possibly looking at the catalyst in a differential scanning calorimeter for the energy required to heat the substance.

Will continue to perform auto-oxidation reactions with similar structure catalysts using other transition metals as it is reported that electrocatalytical activity decreases in the following order of Fe>Co>Ni>Cu>H (unsubstituted) but little to no research has been performed on others. Following the principles of diagonalization and the “knight’s move” patterns in inorganic species.

Continued studies on the properties of porphyrazines in other applications such as a modified carbon paste electrode

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ConclusionThe microwave synthesis is efficient, fast, and requires little solvent. Eliminated the use of a strong acid wash and precipitation by sodium

hydroxide pellets, extraction only requires rinse with alcohol.Ultrasound synthesis was attempted but not successful. It does however

aid in the overall reaction of the microwave synthesis by ensuring that less unreacted materials remain behind.

The 2,3- and 3,4-pyridinyl cobalt catalysts both outperform the phthalocyanine for auto-oxidation of thiols

The 2,3-pyrazinyl cobalt compound is equivalent to the phthalocyanine in terms of performance but synthesis yields are lower than expected. It does have a slight advantage as it is soluble in more solvents.

Thank You! Questions?Special Acknowledgement to:

Dr. Voegel and Southeastern Louisiana University.

My fellow researchers Katherine Parenteau, Shanell Amorello, Pankaj Jairu, and David Cox for their work and support.

Charles McElroy IVEmail: [email protected]

mailto:[email protected]

Charles McElroy IV, ShaNell Amorello, Dr. Phillip VoegelDepartment of Chemistry and Physics – Southeastern Louisiana University

Facile Microwave Synthesis and Study of Catalytic Properties of Cobalt(II)Porphyrazinyl Compounds

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AbstractFive sets of cobalt (II) porphyrazines were synthesized using a time

efficient one-pot microwave reaction method and then used as catalysts for aerobic oxidation of a series of thiols leading to the formation of a disulfide bond. In addition to the more rapid catalyst synthesis, the clean-up procedures are also more efficient. The four catalysts differ in the functional groups on the outer edges of the compounds. The synthesized catalysts include cobalt (II) phthalocyanine, two isomers of cobalt (II) pyridinoporphyrazine, cobalt(II) pyrazine-porphyrazine, and the proposed cobalt(II) imidazoylporphyrazine. For a series of eight thiols ranging from 2-methylbutylthiol to decanethiol using a 30 minute reaction, the minimum conversion was 25% for 2-methyl-1-butanethiol with a maximum conversion of 87% for octanethiol with a cobalt phthalocyanine catalyst. Using the same conditions with the cobalt (II) 2,3-pyridinoporphyrazine catalyst, the minimum conversion was 71% for pentane and the maximum conversion was 98% for octanethiol. The kinetics of the disulfide bridging reaction was studied using reaction times varied from 5 minutes to 30 minutes using two simple thiols selected from based on conversion efficiency from the initial 30 minute reactions. The reactions appear to be first order with respect to thiol concentrations. With better a better synthetic method and proven efficiency in Merox reactions, further research can be performed on similar structures.

facile microwave synthesis and study of catalytic properties

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