Zeolites as Nucleophilic Reagents

1
Zeolites as Nucleophilic Reagents

• Reactions with Organophosphonates.
• Reactions with Organohalides.

Szu-Wei Yang, Charles W. Kanyi, Jürgen T.
Schulte, Justin B. Sanbur, Jack D. Fox, Barry R.
Jones, and David C. Doetschman,
Department of Chemistry, Binghamton
University Binghamton, New York
2
Zeolites the Basic Material

• Faujasite Zeolites, NaX and NaY
• Aluminosilicate Materials, Particle Size 2-10
  mm
• Microscopic Structure
• Large Cages Connected by Open Channels
• Internal Pore Structure Allows Sizable Organic
  Molecules to Be Absorbed and Retained
• Relevant Features
• Inward directed Os
• Presence (NaX) Absence(NaY)
• of supercage cations (Na)

3
I. Zeolite Reactions with Organophosphonates
Among organophsphonates are the X and G classes
of chemical weapons agents (CWAs).
We examined the phos-phonate group
simulant, dimethyl methylphos-phonate, DMMP
VX
(to scale)
Sarin
Faujasite Zeolite
4
Comments on Experimental Methods

• Scrupulous zeolite drying 400oC, 10-5 to 10-4
  torr.
• Control water content by evaporative addition of
  weighed amounts, 0-30 H2O per supercage(sc).
• Subsequent evaporative addition of controlled
  amounts of DMMP (these experiments 1/sc).
• OR
• Subsequent addition of DMMP (1/sc) in CDCl3
  slurry, RT or mild heating, centrifugation, THF
  rinse, centrifugation.
• Investigations mainly by 1H, 31P solution NMR and
  13C, 31P solid state NMR.
• X-ray and IR zeolite characterization IR of
  products.

5
Summary of Experiments Results

• 99.4 DMMP adsorbed fm. CDCl3 _at_ 0 H2O/sc
• 99.99 adsorbed _at_ gt1 H2O/sc (both 31P NMR)
• No detectable DMMP in THF washes (1H NMR)

Solid state 31P NMR exhibits substantial DMMP
decomposition depending on H2O con- tent and
method of load- ing. Identification of
lines described next.
6
1H, 31P NMR Solution Studies of DMMP Hydrolysis
and MPA Titration

• Methylphosphonic acid (MPA) was titrated with
  NaOH to its first and second equivalences.
• DMMP was subjected to DCl hydrolysis in D2O.

7
Proposed Mechanism of DMMP Decomposition

• Nucleophilic Attack of Framework Oxygen.
• Followed by Hydrolysis of Ionic Forms with H2O,
  if Present, to Form (III) and (MPA, IV).

(I)
(II)
8
Evidence for the Framework Methyl Species ?

• Formation in from Na0 activated zeolite
  published.
• We have reproduced 13C NMR spectrum(e)
• In DMMP chemistry (a-d)

(a)by evap. (b) 0 H2O (c) 3 H2O (d) 30
H2O (e)authentic
9
Requisite Zeolite Characteristics

• Fact NaY is not reactive! (Wagner and Bartram,
  Langmuir 1999, 15, 8113). Why?
• Higher Al content of NaX
• (a)Places more electron density on framework (O
  atoms).
• (b)Requires placement of Na in supercage sites
  III, III.
• Together these give extra e- push(a) and leaving
  group pull(b) to nucleophilic substitution.

10
II. Reactions with Organohalides.

• Results, more preliminary in nature, cover work
  with CH3X, CH3CH2X (XBr, I), CCl4.
• Dry zeolites (no added H2O), sometimes activated
  with Na0 via zeolite mixture with NaN3(s)
  heating.
• Organohalides are then added to zeolite
  evaporatively.
• Products analyzed by
• IR and GC-MS of gaseous products.
• IR of zeolite and products.
• Diffuse Reflectance UV-Vis EPR before/after
  reaction.
• 1H NMR of air exposed CDCl3 washings (no solvent
  chemistry).
• 13C NMR of air exposed zeolite and products.

11
Experimental Results Focusing on CH3I

• Framework methyl (13C NMR) detected in
• Na0/NaX small amounts in Na0/NaY, NaX, NaY.
• Unreacted CH3I found (1H NMR of wash) in
• NaX, NaY, Na0/NaY, but not in Na0NaX.
• CH3CH3 and minor amounts of CH4 (IR, MS) in
• Na0/NaX and Na0/NaY but not in NaX, NaY.
• Greater CH4 yields in Na0/NaX than Na0/NaY.
• Spectroscopic Evidence for Some of the Results
  Follow.

12
Framework Methyl 13C NMR
(NaY spectrum not available at time of
preparation.)
13
IR of Gas Phase Products
Na0/NaY
Na0/NaX
14
Possible Mechanisms A. When Framework Methyl
Forms (in NaX)
Frame work methyl remains when insufficient Na0
? Does not explain occurrence of small amounts of
CH4.
15
Possible Mechanisms B. When No Framework Methyl
Forms (in NaY) with Framework Mechanism (NaX)
16
Concluding Comments

• Stoichiometry of Na0/CH3I hard to control, as is
  sodalite Na43(NaY), Na65(NaX) vs. Nan0 cluster
  forms of zero-valent Na in the zeolite EPR
  observable, though.
• No end of surprises Friday we found evidence of
  copious I- formation upon addition of H2O to CH3I
  in non-Na0 activated zeolite!!
• I am beginning to be convinced, however, that
  there is a degree of zeolite nucleophilic
  character in this chemistry.

17
Activated Zeolite Chemical Decontamination
Materials

• Purpose
• To develop a material
• For absorbing chemical warfare agents (CWAs) or
  toxic industrial chemicals (TICs).
• For internally neutralizing the absorbed CWAs or
  TICs.
• Effective against CWAs or TICs in plumes or
  clouds.
• Effective against CWAs or TICs deposited on
  surfaces.
• Capable of use as air filter pellets.
• Dispersible
• As an aerosol.
• As vacuum- or inert gas-packed, manually applied
  material.
• Through inert gas-pressurized dry-chemical
  canister nozzle.

18
Needs for this Kind of Material

• Few are Sorbents and Chemical Neutralizers1.
• Zeolite sorbent micron size particles that are
  internally, nanoscopically porous.
• Only patented externally microscopic
  nanoscopic neutralizers
  exist not
  being produced commercially1,2-6.
• Zeolite is Suitable for Pro-Active Use.
• Existing materials are designed for retro-active
  cleanup1.
• Potentially dispersible as aerosol into CWA or
  TIC cloud or mist.
• Potentially dropped from vacuum- or inert
  gas-packed or from dry-chemical canister into
  cloud or mist.
• Conventional Use on Surfaces or in Air-Filtration.

19
Practicality of Zeolite

• Raw Material Is Inexpensive, Non-toxic, and
  Readily Available Through Commercial Suppliers.
• Activated Zeolite Material is Very Light and is
  Expendable.
• Activated Zeolite May Be Stored Indefinitely
  Without Degradation To Its Effectiveness.
• Activated Zeolite is Not Corrosive.
• Hazards Fine Particulate Nature Makes It an Eye
  Irritant and a Respiratory Hazard.

20
Types of Activation of the Zeolite Studied

• Lewis Base Activity
• Low Si/Al ratio of NaX greater framework O
  electron density, relative to previously studied
  zeolite, NaY7.
• Framework oxygen atoms can act as nucleophiles.
• Brønsted Acidity
• By replacement of the Na ions of NaX with H
  (HX)
• NaX NH4 NH4X Na (ion exchange)
• NH4X heat HX(HX-) NH3(g)
• Brønsted Basicity
• By introduction of NaOH, Na into cation sites,
  OH- coordinated.
• NaN3 NaX Na(0)NaX 3/2 N2(g)
• Na(0)NaX H2O OH-NaNaX 1/2 H2(g)

21
Types of Activation of the Zeolite Studied,
continued

• Oxidizing Activity
• Simply by adding the diatomic molecular oxidizer,
  Br2.
• Br2(g) NaX Br2/NaX
• Reducing Activity
• By introduction of Na0 into the sodalite cage or
  supercages, as ionic or neutral clusters,
  respectively.
• NaN3 NaX Na0/NaX 3/2 N2(g)

22
CWA, TICs, and Hazardous Materials Simulants
Studied

• G and X Nerve Agent Simulants
• DMP
• HMPA
• Tribufos
• Omethoate
• DFP
• TPP

23
CWA Simulants, TICs, and Hazardous Materials
Studied

• Mustard Lewisite, HD simulants
• 2CEES
• DES
• Halogenated Hydrocarbon Simulants
• CH3Br
• CH3I
• CH3CH2Br
• CH3CH2I
• CCl4

24
Results from Testing the G X CWA Simulants
25
Conclusions from Testing the G X CWA Simulants

• Performance Based mainly on the disappearance of
  simulant from solution and extract.
• Performance Lewis basic ? Brønsted acid gt
  Brønsted basic gt oxidizing (no test of reducing
  zeolite done).
• No one zeolite was wholly effective against HMPA
  or Tribufos, due to absorption size exclusion.
• The Brønsted basic oxidizing zeolites are not
  very effective, possible due to NaOH Br2
  excluding absorbates.
• Lewis basic Brønsted acid are comparable.
• Brønsted acid should also have Lewis basicity.
• Suggests only one mechanism operative in all
  zeolites.

26
Evidence For Mechanism of Phosphonate Simulant
Decomposition

• Solid state 31P NMR of DMP in NaX with 0-3H2O/sc
  exhibit the following species with little
  residual DMP (d authenticated by methylphosphonic
  acid titration)
• In NaX with 0-3 H2O/sc there is also solid state
  31P NMR of unreacted DMP at d 38-40 ppm
  (shifted in NaX environment from solution
  33-35ppm) DMP is increasing mobile with
  increasing numbers of H2O/sc.
• Peaks seen d 30-34ppm are hydrolyzed acid
  forms?

d 21-23ppm
d 25-28ppm
27
Lower Limits to Speed of Action against G X
Simulant DMP

• H1 of DMP/ HX CDCl3 Slurry _at_ Room T
• Gaseous DMP IR Spectra over HX(s) _at_ Room T.

28
Results from Testing the Mustard/Lewisites
Simulants

• 13C NMR analysis of residual in CDCl3 solvent

29
Conclusions from Testing the Mustard/Lewisites
Simulants

• Little absorption of DES or 2CEES observed.
• Little change in DES is observed.
• Significant changes in 2CEES are observed.
• Suggests organohalogen chemistry. See next
  sections.
• No detailed analysis of 13C NMR or 1H NMR (not
  shown) has been undertaken.
• Brønsted base oxidizing zeolites give more
  complex array of products (more effective ?)
• No solid state NMR studies have been undertaken.
• Significantly more work is needed on this aspect.

30
Results from Testing the Reducing Zeolite on
Halogen Organohalogen TIC Simulants

• Analysis shows formation of cation-associated
  halide or trihalide ion in tests with Br2 I2.
• Analysis shows formation of alkanes and
  cation-associated halide ion in tests with CH3Br,
  CH3I, CH3CH2Br, CH3CH2I.
• Product alkane chain lengths are twice the
  simulant alkyl chain length.
• In tests with CCl4 evidence is found for minor
  degradation of the zeolite framework in the form
  of CO, CO2, and carbonate formation.

31
Proposed Mechanism of the Reducing Zeolite
Reaction with Organohalogen
32
Present Past Support for the Basic Research Work

• Research Corporation.
• Institute for Hazardous Materials Management.
• Binghamton University, College of Arts Sciences.

33
Seeking Product Development Partners

• Development testing of zeolite in forms
  effective against CWAs or TICs in plumes or
  clouds.
• Airborne or rocket dispersal as an aerosol.
• Airborne inert gas-pressurized dry-chemical
  canister nozzle dispersal.
• Airborne vacuum- or inert gas-packed, for manual
  drop application.
• Development testing of zeolite in forms
  effective against CWAs or TICs deposited on
  surfaces or in spills.
• Hand held and/or robot operated inert
  gas-pressurized dry-chemical canister nozzle
  dispersal.
• Vacuum-packing or inert gas-packing for manual
  application.
• Automated dumping on potential industrial
  accident sites.
• Development testing of zeolite in forms for use
  as air filters.
• Pellet manufacture with maintenance of zeolite
  activity and porosity.

34
Bibliography

• 1. Wide Area Decontamination CB
  Decontamination Technologies, Equipment and
  Projects Literature Search and Market Survey,
  performed by the Battelle Memorial Institute for
  the Air Force Research Laboratory, Chemical and
  Biological Defense Group, Aberdeen Proving
  Ground, MD, 1999.
• 2. P. W. Bartram and G. W. Wagner, US Patent N.
  6,537,382 B1, March 25, 2003.
• 3. O. Koper, K. J. Llabunde, L. S. Martin, K. B.
  Knoppenberger, L. L. Hladky, and S. P. Decker, U.
  S. Patent No. 2004/0045479 A1, December 11, 2003.
• 4. K. J. Klabunde, A. F. Bedlo, O. B. Koper, and
  M. Sigel, US Patent No. 2004/0065619 A1, April 8,
  2004.
• 5. S. Rajagopalan, O. B. Koper, K. J. Kabunde,
  P. S. Malchesky, and S. Winecki, US Patent No.
  2003/0226443 A1.
• 6. A. Giletto, W. White, A. J. Cisar, G. D.
  Hitchens, and J. Fyffe, US Patent No. 2004/009095
  A1.
• 7. G. W. Wagner and P. W. Bartram, Reactions of
  VX, HD, and Their Simulants with NaY and AgY
  Zeolites. Desulfurization of VX on AgY,
  Langmuir, 15, 8113 (1999).
• 8. Evidence exists for the nucleophilic attack
  of framework oxygen on methyl group carbons
  attached to good leaving groups. D. Jaumain and
  B.-L. Su, J. Mol. Catalysis A Chemical 107, 263
  (2003) S. Vratislaw, M. Dlouha, and V. Bosacek,
  Physica B Condensed Matter 276-278, 929 (2000)
  D. Carmello, E. Finocchio, A. Marsella, B.
  Cremaschi, M. Padovan, and G. Busca, J. Catal.
  191, 354 (2000).