Doing without Phosgene, Hydrogen Cyanide, and Formaldehyde PART II

Reducing Toxicity of Isocyanates Associated with occupational asthma; Require a hood; toluenediisocyanate Ways to reduce toxicity: -Increasing MW; - Chemical conversion;

Chemical Conversion of Isocyanates 1. Conversion to carbodiimides RNCO 2. Reaction with polymeric diol

Various HA Agents Can Add to Isocyanate Group alchohol isocyanate polyurethane amine isocyanate polyurea -used to inactivate isocyanate group -require thermal unblocking -volatile blocking agent

Blocked Prepolymer Mixtures Methyl ethyl ketoxime Tengfei Shen, Mangeng Lu, Liyan Liang; Synthesis and properties of biodegradable polyurethane crosslinkers from methyl ethyl ketoxime-blocked diisocyanate. Macromolecular Research, August 2012, Volume 20, Issue 8, pp 827-834

Thermally Reversible Polyurethane Polymers Dissociation Temperature Alcohol > Lactam > phenol > ketoxime >active methylene compound 1,4-butanediol 4,4’-isopropylidendipenol (bisphenol A, BPA) 4,4-diphenyldiisocyanate

4,4’-Isopropylidendipenol (bisphenol A, BPA) http://www.edf.org/health/four-reasons-bpa-free-wont-protect-you?s_src=ggad&s_subsrc=bpa&gclid=CM_c2IT1wsACFaTm7Aodo1cA2Q

Polymerization of Isocyanate Monomers

Polymers Made without Isocyanates: Reactions of Cyclic Carbonates with Diamines Contras: low MW (9350 and 5345) Possible solution: use chain extension agents

Reactions of Cyclic Carbonates with Diamines

Applications of Polycarbonate Polymers http://atlasthermoforming.com.au/wp-content/gallery/poly-carb/polycarbonate_chair.png http://www.metalandpolycarbonatesheets.com/durotuff/polycarbonate-sheet-1.jpg http://www.bisphenol-a-europe.org/uploads/images/EN_Socio-economic-contribution_011013-2_08.png http://gallinausa.com/wp-content/uploads/2012/02/547.photo_.c.jpg

Polycarbonates Traditional polycarbonate synthesis involves phosgene Solvent: methylene chloride Base: pyridine, NaOH

Ester Exchange Method for Polycarbonate Synthesis No solvents, no salt by-products Needs: High temperature Vacuum/N2 flow to extract phenol http://chem.chem.rochester.edu/~chem424/pcsynth.htm

CO2 Can Be an Alternative to CO in Polycarbonates Synthesis

Summary for Phosgene Elimination of phosgene in PC production is getting commercialized (SABIC, Asahi, Mitsubishi) Non-Phosgene Polycarbonate from CO2 - Industrialization of Green Chemical Process Authors: Shinsuke Fukuoka (Asahi Kasei Chemicals Corporation) Chapter 1. Introduction: Society And Chemical Industry Chapter 2. Background Of Polycarbonate Chapter 3. General Method For Synthesis Of Polycarbonate Chapter 4. Technological Aspects Of The Industrial Processes For Producing Aromatic Polycarbonates Using Carbon Monoxide (Co) As A Starting Material Part 1. Interfacial Polycondensation Phosgene Process Chapter 5. Technological Aspects Of The Industrial Processes For Producing Aromatic Polycarbonates Using Carbon Monoxide (Co) As A Starting Material Part 2. Non-phosgene Process Chapter 6. General Aspect Of Non-Phosgene Polycarbonate Process From Co2 (Asahi Kasei Process) Chapter 7. Monomer Production Technology From Co2 (Asahi Kasei Process) Chapter 8. Melt Polymerization Technology Of Asahi Kasei Process Chapter 9. Excellent Features Of Polycarbonate Produced By Asahi Kasei Non-Phosgene Process Chapter 10. Economical Features Of Asahi Kasei Non-Phosgene Polycarbonate Process Chapter 11. Contribution Of Asahi Kasei Non-Phosgene Polycarbonate Process To Society Chapter 12. Other Approach 1 – Outline Of Chemical Fixation Of Co2 Into Polymer Chapter 13. Other Approach 2 – Development Of Non-Phosgene Mdi Process

Summary for Phosgene Polyurethane Synthesis Elimination of phosgene from isocyanate synthesis Methyl isocyanate synthesis on demand (DuPont) Advances in pest management to eliminate carbamates Challenge: On demand production of other isocyanates Create similar products synthetized from less harmful materials

General Toxicity Rules for Safer Substitutions CO2 is less toxic than CO Ethanol is less toxic than methanol Aliphatic amines are less toxic than aromatic and nitro aromatic compaunds Routs to amines through diols are less toxic than through nitriles Higher MW substance is less toxic that low MW substance Roots via carboxylic acid are less toxic than via nitro compounds Solids give less problems than liquids

Replacements for HCN 1. Replacements in gold ore extraction - Thiourea (can be reused)/ thiourea + Fe(III) sulfate in ionic liquid - Chloride on activated carbon 2. Replacements in adipic acid synthesis Renewable raw materials (petroselenic acid, cis-muconic acid

Elimination of Formaldehyde Phenol-formaldehyde and urea-formaldehyde adhesives for the plywood and particle board

Elimination of Formaldehyde Crease proofing resin for cotton Being replaced by 1,2,3,4-butanetetracarboxylic acid and poly(maleic acid) http://oecotextiles.wordpress.com/2011/01/04/formaldehyde-in-your-fabrics/