Hexamethylene diisocyanate

Last updated
Hexamethylene diisocyanate
Hexamethylene-diisocyanate-2D-skeletal.png
Hexamethylene-diisocyanate-3D-vdW.png
Names
Preferred IUPAC name
1,6-Diisocyanatohexane
Other names
HDI
1,6-hexane diisocyanate
Identifiers
3D model (JSmol)
ChEBI
ChemSpider
ECHA InfoCard 100.011.350 OOjs UI icon edit-ltr-progressive.svg
PubChem CID
UNII
  • InChI=1S/C8H12N2O2/c11-7-9-5-3-1-2-4-6-10-8-12/h1-6H2 Yes check.svgY
    Key: RRAMGCGOFNQTLD-UHFFFAOYSA-N Yes check.svgY
  • InChI=1/C8H12N2O2/c11-7-9-5-3-1-2-4-6-10-8-12/h1-6H2
    Key: RRAMGCGOFNQTLD-UHFFFAOYAI
  • O=C=N\CCCCCC/N=C=O
Properties
C8H12N2O2
Molar mass 168.2 g/mol
AppearanceColourless liquid
Odor sharp, pungent [1]
Density 1.047 g/cm3, liquid
Melting point −67 °C (−89 °F; 206 K)
Boiling point 255 °C (491 °F; 528 K)
Vapor pressure 0.05 mmHg (25 °C) [1]
Viscosity 3 cP at 25 °C
Hazards
Flash point 130–140 °C (266–284 °F; 403–413 K) (Cleveland open cup)
NIOSH (US health exposure limits):
PEL (Permissible)
none [1]
REL (Recommended)
TWA 0.005 ppm (0.035 mg/m3) C 0.020 ppm (0.140 mg/m3) [10-minute] [1]
IDLH (Immediate danger)
N.D. [1]
Related compounds
Related isocyanates
Isophorone diisocyanate
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Yes check.svgY  verify  (what is  Yes check.svgYX mark.svgN ?)

Hexamethylene diisocyanate (HDI) is the organic compound with the formula (CH2)6(NCO)2. It is classified as an diisocyanate. It is a colorless liquid. [2] It has sometimes been called HMDI [3] but this not usually done to avoid confusion with Hydrogenated MDI.

Contents

Synthesis

Compared to other commercial diisocyanates, HDI is produced in relatively small quantities, accounting for (with isophorone diisocyanate) only 3.4% of the global diisocyanate market in the year 2000. [4] It is produced by phosgenation of hexamethylene diamine.

Applications

Aliphatic diisocyanates are used in specialty applications, such as enamel coatings which are resistant to abrasion and degradation by ultraviolet light. These properties are particularly desirable in, for instance, the exterior paint applied to aircraft and vessels. HDI is also sold oligomerized as the trimer or biuret which are used in automotive refinish coatings. [5] [6] Although more viscous in these forms, it reduces the volatility and toxicity. At least 3 companies sell material in this form commercially. It is also used as an activator in process of in situ polymerization of caprolactam i.e. cast nylon process. HDI is also used bisoxazolidine synthesis as the hydroxyl group on the molecule allows for further reaction with hexamethylene diisocyanate. [7] [8]

Toxicity

HDI is considered toxic, and its pulmonary toxicity has been studied as well as its oligomers. [9] [10] [11] [12]

See also

Related Research Articles

<span class="mw-page-title-main">Phosgene</span> Toxic gaseous compound (COCl2)

Phosgene is an organic chemical compound with the formula COCl2. It is a toxic, colorless gas; in low concentrations, its musty odor resembles that of freshly cut hay or grass. It can be thought of chemically as the double acyl chloride analog of carbonic acid, or structurally as formaldehyde with the hydrogen atoms replaced by chlorine atoms. Phosgene is a valued and important industrial building block, especially for the production of precursors of polyurethanes and polycarbonate plastics.

<span class="mw-page-title-main">Polyurethane</span> Polymer composed of a chain of organic units joined by carbamate (urethane) links

Polyurethane refers to a class of polymers composed of organic units joined by carbamate (urethane) links. In contrast to other common polymers such as polyethylene and polystyrene, polyurethane is produced from a wide range of starting materials. This chemical variety produces polyurethanes with different chemical structures leading to many different applications. These include rigid and flexible foams, and coatings, adhesives, electrical potting compounds, and fibers such as spandex and polyurethane laminate (PUL). Foams are the largest application accounting for 67% of all polyurethane produced in 2016.

<span class="mw-page-title-main">Isocyanate</span> Chemical group (–N=C=O)

In organic chemistry, isocyanate is the functional group with the formula R−N=C=O. Organic compounds that contain an isocyanate group are referred to as isocyanates. An organic compound with two isocyanate groups is known as a diisocyanate. Diisocyanates are manufactured for the production of polyurethanes, a class of polymers.

<span class="mw-page-title-main">Methyl isocyanate</span> Chemical compound

Methyl isocyanate (MIC) is an organic compound with the molecular formula CH3NCO. Synonyms are isocyanatomethane and methyl carbylamine. Methyl isocyanate is an intermediate chemical in the production of carbamate pesticides (such as carbaryl, carbofuran, methomyl, and aldicarb). It has also been used in the production of rubbers and adhesives. As an extremely toxic and irritating compound, it is very hazardous to human health. It was the principal toxicant involved in the infamous Bhopal gas disaster, which officially killed around 20,000 people in total. It is also a very potent lachrymatory agent.

<span class="mw-page-title-main">Dichloromethane</span> Chemical compound

Dichloromethane is an organochlorine compound with the formula CH2Cl2. This colorless, volatile liquid with a chloroform-like, sweet odor is widely used as a solvent. Although it is not miscible with water, it is slightly polar, and miscible with many organic solvents.

<span class="mw-page-title-main">Oxazolidine</span> Chemical compound

Oxazolidine is a five-membered heterocycle ringwith the formula (CH2)3(NH)O.The O atom and NH groups are not mutually bonded, in contrast to isoxazolidine. Oxazolidines are derivatives of the parent oxazolidine owing to the presence of substituents on carbon and/or nitrogen. Oxazolines are unsaturated analogues of oxazolidines.

In organic chemistry, a polyol is an organic compound containing multiple hydroxyl groups. The term "polyol" can have slightly different meanings depending on whether it is used in food science or polymer chemistry. Polyols containing two, three and four hydroxyl groups are diols, triols, and tetrols, respectively.

<span class="mw-page-title-main">Toluene diisocyanate</span> Chemical compound

Toluene diisocyanate (TDI) is an organic compound with the formula CH3C6H3(NCO)2. Two of the six possible isomers are commercially important: 2,4-TDI (CAS: 584-84-9) and 2,6-TDI (CAS: 91-08-7). 2,4-TDI is produced in the pure state, but TDI is often marketed as 80/20 and 65/35 mixtures of the 2,4 and 2,6 isomers respectively. It is produced on a large scale, accounting for 34.1% of the global isocyanate market in 2000, second only to MDI. Approximately 1.4 billion kilograms were produced in 2000. All isomers of TDI are colorless, although commercial samples can appear yellow.

<span class="mw-page-title-main">Methylene diphenyl diisocyanate</span> Aromatic diisocyanate

Methylene diphenyl diisocyanate (MDI) is an aromatic diisocyanate. Three isomers are common, varying by the positions of the isocyanate groups around the rings: 2,2′-MDI, 2,4′-MDI, and 4,4′-MDI. The 4,4′ isomer is most widely used, and is also known as 4,4′-diphenylmethane diisocyanate. This isomer is also known as Pure MDI. MDI reacts with polyols in the manufacture of polyurethane. It is the most produced diisocyanate, accounting for 61.3% of the global market in the year 2000.

<span class="mw-page-title-main">2,4-Dinitrotoluene</span> Organic chemical compound

2,4-Dinitrotoluene (DNT) or dinitro is an organic compound with the formula C7H6N2O4. This pale yellow crystalline solid is well known as a precursor to trinitrotoluene (TNT) but is mainly produced as a precursor to toluene diisocyanate.

<span class="mw-page-title-main">Polyisocyanurate</span> Type of plastic typically used for thermal insulation

Polyisocyanurate, also referred to as PIR, polyiso, or ISO, is a thermoset plastic typically produced as a foam and used as rigid thermal insulation. The starting materials are similar to those used in polyurethane (PUR) except that the proportion of methylene diphenyl diisocyanate (MDI) is higher and a polyester-derived polyol is used in the reaction instead of a polyether polyol. The resulting chemical structure is significantly different, with the isocyanate groups on the MDI trimerising to form isocyanurate groups which the polyols link together, giving a complex polymeric structure.

<span class="mw-page-title-main">Isophorone diisocyanate</span> Chemical compound

Isophorone diisocyanate (IPDI) is an organic compound in the class known as isocyanates. More specifically, it is an aliphatic diisocyanate. It is produced in relatively small quantities, accounting for only 3.4% of the global diisocyanate market in the year 2000. Aliphatic diisocyanates are used, not in the production of polyurethane foam, but in special applications, such as enamel coatings which are resistant to abrasion and degradation from ultraviolet light. These properties are particularly desirable in, for instance, the exterior paint applied to aircraft.

<span class="mw-page-title-main">Hexamethylenediamine</span> Chemical compound

Hexamethylenediamine is the organic compound with the formula H2N(CH2)6NH2. The molecule is a diamine, consisting of a hexamethylene hydrocarbon chain terminated with amine functional groups. The colorless solid (yellowish for some commercial samples) has a strong amine odor. About 1 billion kilograms are produced annually.

Moisture-cure polyurethanes -- or polyurethane prepolymer -- are isocyanate-terminated prepolymers that are formulated to cure with ambient water. Cured PURs are segmented copolymer polyurethane-ureas exhibiting microphase-separated morphologies. One phase is derived from a typically flexible polyol that is generally referred to as the “soft phase”. Likewise the corresponding “hard phase” is born from the di- or polyisocyanates that through water reaction produce a highly crosslinked material with softening temperature well above room temperature.

Polyurethane dispersion, or PUD, is understood to be a polyurethane polymer resin dispersed in water, rather than a solvent, although some cosolvent maybe used. Its manufacture involves the synthesis of polyurethanes having carboxylic acid functionality or nonionic hydrophiles like PEG incorporated into, or pendant from, the polymer backbone. Two component polyurethane dispersions are also available.

<span class="mw-page-title-main">Tetramethylxylylene diisocyanate</span> Chemical compound

Tetramethylxylylene diisocyanate (TMXDI) is an organic compound with the formula C6H4(CMe2NCO)2 (Me = CH3). Introduced in the 1980s by American Cyanamid, the molecule features two isocyanate groups. TMXDI is generally classified as an aliphatic isocyanate, which are generally more UV stable than their aromatic counterparts.

<span class="mw-page-title-main">UV-328</span> Chemical compound

UV-328 is a chemical compound that belongs to the phenolic benzotriazoles. It is a UV filter that is used as an antioxidant for plastics.

<span class="mw-page-title-main">Dimethylolpropionic acid</span> Organic compound with one carboxyl and two hydroxyl groups

Dimethylolpropionic acid (DMPA) is a chemical compound that has the full IUPAC name of 2,2-bis(hydroxymethyl)propionic acid and is an organic compound with one carboxyl and two hydroxy groups. It has the CAS Registry Number of 4767-03-7.

Hydrogenated MDI (H12MDI or 4,4′-diisocyanato dicyclohexylmethane) is an organic compound in the class known as isocyanates. More specifically, it is an aliphatic diisocyanate. It is a water white liquid at room temperature and is manufactured in relatively small quantities. It is also known as 4,4'-methylenedi(cyclohexyl isocyanate) or methylene bis(4-cyclohexylisocyanate) and has the formula CH2[(C6H10)NCO]2.

Blocked isocyanates are organic compounds that have their isocyanate functionality chemically blocked to control reactivity. They are the product of an isocyanate moiety and a suitable blocking agent. It may also be a polyurethane prepolymer that is NCO terminated but this functionality has also been chemically reacted with a blocking agent. They are usually used in polyurethane applications but not always. They are extensively used in industrial applications such as coatings, sealants and adhesives.

References

  1. 1 2 3 4 5 NIOSH Pocket Guide to Chemical Hazards. "#0320". National Institute for Occupational Safety and Health (NIOSH).
  2. ↑ Christian Six; Frank Richter (2005). "Isocyanates, Organic". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a14_611. ISBN   3-527-30673-0.
  3. ↑ PubChem. "Hexamethylene diisocyanate". pubchem.ncbi.nlm.nih.gov. Retrieved 2022-08-04.
  4. ↑ Randall, David; Lee, Steve (2002). The Polyurethanes Book. New York: Wiley. ISBN   978-0-470-85041-1.
  5. ↑ Jeffries, Michael; Gambino, Charles; Pierce, Joe. "Acrylate Monomer Free/VOC Compliant Ultraviolet-A Radiation Curable Technology for Automotive Refinish Clear Coat" (PDF).
  6. ↑ Gregorovich, Basil V.; Adamsons, Karlis; Lin, Li (2001-11-01). "Scratch and mar and other mechanical properties as a function of chemical structure for automotive refinish coatings". Progress in Organic Coatings. Athens 2000. 43 (1): 175–187. doi:10.1016/S0300-9440(01)00187-4. ISSN   0300-9440.
  7. ↑ "2-[2-(propan-2-yl)-1,3-oxazolidin-3-yl]ethanol - Registration Dossier - ECHA". echa.europa.eu. Retrieved 2018-11-14.
  8. ↑ Howarth, GA (July 2003). "Polyurethanes, polyurethane dispersions and polyureas: Past, present and future". Surface Coatings International Part B: Coatings Transactions. 86 (2): 111–118. doi:10.1007/bf02699621. ISSN   1476-4865. S2CID   93574741.
  9. ↑ Lee, Chun-Ting; Friedman, Mitchell; Poovey, Halet G; Ie, Susanti R; Rando, Roy J; Hoyle, Gary W (2003-05-01). "Pulmonary toxicity of polymeric hexamethylene diisocyanate aerosols in mice". Toxicology and Applied Pharmacology. 188 (3): 154–164. doi:10.1016/S0041-008X(03)00096-6. ISSN   0041-008X. PMID   12729715.
  10. ↑ Pauluhn, J. (2000-11-01). "Inhalation Toxicity of 1,6-Hexamethylene Diisocyanate Homopolymer (HDI-IC) Aerosol: Results of Single Inhalation Exposure Studies". Toxicological Sciences. 58 (1): 173–181. doi: 10.1093/toxsci/58.1.173 . ISSN   1096-0929. PMID   11053554.
  11. ↑ Mohr, Jürgen Pauluhn, Ulrich (2001-01-01). "INHALATION TOXICITY OF 1,6-HEXAMETHYLENE DIISOCYANATE HOMOPOLYMERS (HDI-IC AND HDI-BT): Results of Subacute and Subchronic Repeated Inhalation Exposure Studies". Inhalation Toxicology. 13 (6): 513–532. doi:10.1080/08958370118600. ISSN   0895-8378. PMID   11445890. S2CID   13505170.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  12. ↑ Wisnewski, Adam V.; Liu, Qing; Miller, Jing-Jing; Magoski, Nadine; Redlich, Carrie A. (2002-09-01). "Effects of hexamethylene diisocyanate exposure on human airway epithelial cells: in vitro cellular and molecular studies". Environmental Health Perspectives. 110 (9): 901–907. doi:10.1289/ehp.02110901. PMC   1240990 . PMID   12204825.
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