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Methylene diphenyl diisocyanate is an aromatic diisocyanate.
Three isomers are common, varying by the positions of the isocyanate groups around the rings: 2,2′-Methylene diphenyl diisocyanate, 2,4′-Methylene diphenyl diisocyanate, and 4,4′-Methylene diphenyl diisocyanate.
The 4,4′ isomer is most widely used, and is also known as 4,4′-diphenylmethane diisocyanate.
CAS: 101-68-8
MF: C15H10N2O2
MW: 250.25
EINECS: 202-966-0
Synonyms
1,1’-methylenebis(4-isocyanato)-benzene;para,para’-methylenebis(phenylisocyanate);Rubinate 44;Rubinate LF-168;rubinate44;METHYLENEBIS(P-PHENYL ISOCYANATE);METHYLENEDIPHENYL 4,4'-DIISOCYANATE;METHYLENEDIPHENYLENE DIISOCYANATE
This isomer is also known as Pure Methylene diphenyl diisocyanate.
Methylene diphenyl diisocyanate reacts with polyols in the manufacture of polyurethane.
Methylene diphenyl diisocyanate is the most produced diisocyanate, accounting for 61.3% of the global market in the year 2000.
Methylene diphenyl diisocyanate is used in the manufacture of various polyurethane products - elastic and rigid foams, paints, lacquers, adhesives, binding agents, synthetics rubbers, and elastomeric fibers.
A diisocyanate consisting of diphenylmethane with two isocyanate groups at the 4- and 4'-positions.
Methylene diphenyl diisocyanate is a light yellow colored solid.
Methylene diphenyl diisocyanate is not soluble in water.
Methylene diphenyl diisocyanate may be toxic by ingestion, inhalation, or skin absorption.
If in a solution Methylene diphenyl diisocyanate may or may not burn depending on the nature of the material and/or the solvent.
Methylene diphenyl diisocyanate's used to make plastics.
Methylene diphenyl diisocyanate Chemical Properties
Melting point: 38-44 °C
Boiling point: 392 °C
density: 1.19
vapor pressure: 0.066 hPa (20 °C)
refractive index: 1.5906 (estimate)
Fp: 196 °C
storage temp.: -20°C
solubility: 2g/l (decomposition)
form: solid
Specific Gravity: 1.180
color: White to Almost white
explosive limit: 0.4%(V)
Water Solubility: decomposes
FreezingPoint: 37℃
Sensitive: Moisture Sensitive/Lachrymatory
BRN: 797662
Dielectric constant: 10.0（Ambient）
Exposure limits ACGIH:TLV-TWA 0.005 ppm (0.051 mg/m3)
OSHA:PEL-Ceiling 0.02 ppm (0.2 mg/m3)
NIOSH:REL-TWA 0.05 mg/m3; REL-Ceiling 0.2 mg/m3[10-min]
Stability: Stable. Combustible. Incompatible with strong oxidizing agents. Reacts violently with alcohols.
InChI: 1S/C15H10N2O2/c18-10-16-14-5-1-12(2-6-14)9-13-3-7-15(8-4-13)17-11-19/h1-8H,9H2
InChIKey: UPMLOUAZCHDJJD-UHFFFAOYSA-N
CAS DataBase Reference: 101-68-8(CAS DataBase Reference)
NIST Chemistry Reference: Methylene diphenyl diisocyanate(101-68-8)
IARC: 3 (Vol. 19, Sup 7, 71) 1999
EPA Substance Registry System: Methylene diphenyl diisocyanate (101-68-8)
Methylene diphenyl diisocyanate is a white to light-yellow, odorless flakes. A liquid above 37C.
Applications
The major application of Methylene diphenyl diisocyanate is the production of rigid polyurethane.
These rigid polyurethane foams are good thermal insulators and used in nearly all freezers and refrigerators worldwide, as well as buildings.
Typical polyols used are polyethylene adipate (a polyester) and poly(tetramethylene ether) glycol (a polyether).
Methylene diphenyl diisocyanate is also used as an industrial strength adhesive, which is available to end consumers as various high-strength bottled glue preparations.
Methylene diphenyl diisocyanate is widely used in the production ofrigid urethane foam products, coatings, andelastomers.
Methylene diphenyl diisocyanate is widely used in polyurethane coatings, Methylene diphenyl diisocyanate is made of polyurethane foam used as a warm (cold), building materials, vehicle, ship parts; masterwork can made car Block, buffer, synthetic leather, non plastic polyurethane, polyurethane elastic fiber, no plastic elastic fibers, films, adhesives.
Methylene diphenyl diisocyanate is used in the preparation of polyurethane resin and Spandex fibers; bonding of rubber to rayon; diisoeyanate in the production of polyurethane lacquers, foam plastics, rubber, and glues.
Preparation
Phosgene (800 g, 8 mol) (for a safe source) was dissolved in o-dichlorobenzene (2000 mL), and the resulting solution was cooled in an ice-salt bath.
To the stirred solution, a hot solution of Methylene diphenyl diisocyanate (200 g, 1.01 mol) in o-dichlorobenzene (1000 mL) was slowly added through a heated dropping funnel.
The rate of addition was regulated so that the temperature of the phosgene solution did not rise substantially above 0°C.
The fine suspension that resulted was slowly heated and additional phosgene (700 g, 7.1 mol) was added at 130 °C until a clear solution appeared.
After purging with carbon dioxide, the solvent was removed in vacuo and the product was purified by vacuum distillation.
At 156–158 °C (0.1 mmHg), 215 g (0.85 mol, 84%) of Methylene diphenyl diisocyanate was obtained.
Several procedures for the preparation of isocyanates with phosgene have been described.
Nevertheless, many of them require the delivery of gaseous phosgene from an external source, such as a pressurized cylinder.
Toxicity evaluation
The primary health concern with exposure to Methylene diphenyl diisocyanate is dermal and respiratory sensitization.
Both are initiated by conjugation of Methylene diphenyl diisocyanate groups with macromolecules at the point of contact, which forms a hapten that subsequently activates immunologic processes resulting in sensitization.
Data in animals indicate dermal contact with Methylene diphenyl diisocyanate can lead to respiratory sensitization.
However, the human relevance of these observations is unclear since there are no validated animal models that accurately reflect the respiratory sensitization process and responses seen in humans.
The low incidence of pulmonary tumors observed in chronic inhalation studies at maximum tolerated concentrations of Methylene diphenyl diisocyanate is most likely the result of nongenotoxic cell proliferation associated with chronic inflammation and/or hyperplasia rather than a direct effect on DNA.
