Hexamethylene diisocyanate
{{chembox
| Watchedfields = changed
| verifiedrevid = 443857420
| Name = Hexamethylene diisocyanate
| ImageFile = Hexamethylene-diisocyanate-2D-skeletal.png
| ImageClass = skin-invert-image
| ImageName = Hexamethylene diisocyanate
| ImageFile1 = Hexamethylene-diisocyanate-3D-vdW.png
| ImageClass1 = bg-transparent
| ImageName1 = Hexamethylene diisocyanate
| PIN = 1,6-Diisocyanatohexane
| OtherNames = HDI
1,6-hexane diisocyanate
|Section1={{Chembox Identifiers
| IUPHAR_ligand = 6291
| ChEBI_Ref = {{ebicite|correct|EBI}}
| ChEBI = 53578
| SMILES = O=C=N\CCCCCC/N=C=O
| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}
| ChemSpiderID = 12637
| PubChem = 13192
| InChI = 1/C8H12N2O2/c11-7-9-5-3-1-2-4-6-10-8-12/h1-6H2
| InChIKey = RRAMGCGOFNQTLD-UHFFFAOYAI
| StdInChI_Ref = {{stdinchicite|correct|chemspider}}
| StdInChI = 1S/C8H12N2O2/c11-7-9-5-3-1-2-4-6-10-8-12/h1-6H2
| StdInChIKey_Ref = {{stdinchicite|correct|chemspider}}
| StdInChIKey = RRAMGCGOFNQTLD-UHFFFAOYSA-N
| CASNo_Ref = {{cascite|correct|CAS}}
| CASNo = 822-06-0
| UNII_Ref = {{fdacite|correct|CAS}}
| UNII = 0I70A3I1UF
| RTECS =
}}
|Section2={{Chembox Properties
| Formula = C8H12N2O2
| MolarMass = 168.2 g/mol
| Appearance = Colourless liquid
| Density = 1.047 g/cm3, liquid
| Solubility =
| MeltingPtC = -67
| MeltingPt_notes =
| BoilingPtC = 255
| BoilingPt_notes =
| pKa =
| pKb =
| Viscosity = 3 cP at 25 °C
| VaporPressure = 0.05 mmHg (25 °C)
}}
|Section3={{Chembox Structure
| MolShape =
| Coordination =
| CrystalStruct =
| Dipole =
}}
|Section7={{Chembox Hazards
| ExternalSDS =
| MainHazards =
| FlashPtC = 130–140
| FlashPt_notes = (Cleveland open cup)
| PEL = none{{PGCH|0320}}
| REL = TWA 0.005 ppm (0.035 mg/m3) C 0.020 ppm (0.140 mg/m3) [10-minute]
}}
|Section8={{Chembox Related
| OtherAnions =
| OtherCations =
| OtherFunction_label = isocyanates
| OtherFunction = Isophorone diisocyanate
| OtherCompounds =
}}
}}
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.{{cite journal|author=Christian Six |author2=Frank Richter |title=Isocyanates, Organic|journal=Ullmann's Encyclopedia of Industrial Chemistry|year=2005|publisher=Wiley-VCH|location=Weinheim|doi=10.1002/14356007.a14_611|isbn=3-527-30673-0 }} It has sometimes been called HMDI{{Cite web |last=PubChem |title=Hexamethylene diisocyanate |url=https://pubchem.ncbi.nlm.nih.gov/compound/13192 |access-date=2022-08-04 |website=pubchem.ncbi.nlm.nih.gov |language=en}} but this not usually done to avoid confusion with Hydrogenated MDI.
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.{{cite book | first=David | last=Randall |author2=Lee, Steve | title=The Polyurethanes Book | publisher=Wiley | location=New York | year=2002 | isbn=978-0-470-85041-1}}
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.{{Cite web |last1=Jeffries |first1=Michael |last2=Gambino |first2=Charles |last3=Pierce |first3=Joe |title=Acrylate Monomer Free/VOC Compliant Ultraviolet-A Radiation Curable Technology for Automotive Refinish Clear Coat |url=https://radtech.org/proceedings/2006/papers/007.pdf}}{{Cite journal |last1=Gregorovich |first1=Basil V. |last2=Adamsons |first2=Karlis |last3=Lin |first3=Li |date=2001-11-01 |title=Scratch and mar and other mechanical properties as a function of chemical structure for automotive refinish coatings |url=https://www.sciencedirect.com/science/article/pii/S0300944001001874 |journal=Progress in Organic Coatings |series=Athens 2000 |language=en |volume=43 |issue=1 |pages=175–187 |doi=10.1016/S0300-9440(01)00187-4 |issn=0300-9440}} 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.{{Cite web|url=https://echa.europa.eu/registration-dossier/-/registered-dossier/6622/1|title=2-[2-(propan-2-yl)-1,3-oxazolidin-3-yl]ethanol - Registration Dossier - ECHA|website=echa.europa.eu|language=en-GB|access-date=2018-11-14}}{{Cite journal|last=Howarth|first=GA|date=July 2003|title=Polyurethanes, polyurethane dispersions and polyureas: Past, present and future|journal=Surface Coatings International Part B: Coatings Transactions|language=en|volume=86|issue=2|pages=111–118|doi=10.1007/bf02699621|s2cid=93574741|issn=1476-4865}}
Toxicity
HDI is considered toxic, and its pulmonary toxicity has been studied as well as its oligomers.{{Cite journal |last1=Lee |first1=Chun-Ting |last2=Friedman |first2=Mitchell |last3=Poovey |first3=Halet G |last4=Ie |first4=Susanti R |last5=Rando |first5=Roy J |last6=Hoyle |first6=Gary W |date=2003-05-01 |title=Pulmonary toxicity of polymeric hexamethylene diisocyanate aerosols in mice |url=https://www.sciencedirect.com/science/article/pii/S0041008X03000966 |journal=Toxicology and Applied Pharmacology |language=en |volume=188 |issue=3 |pages=154–164 |doi=10.1016/S0041-008X(03)00096-6 |pmid=12729715 |issn=0041-008X}}{{Cite journal |last=Pauluhn |first=J. |date=2000-11-01 |title=Inhalation Toxicity of 1,6-Hexamethylene Diisocyanate Homopolymer (HDI-IC) Aerosol: Results of Single Inhalation Exposure Studies |journal=Toxicological Sciences |volume=58 |issue=1 |pages=173–181 |doi=10.1093/toxsci/58.1.173 |pmid=11053554 |issn=1096-0929|doi-access=free }}{{Cite journal |last=Mohr |first=Jürgen Pauluhn, Ulrich |date=2001-01-01 |title=INHALATION TOXICITY OF 1,6-HEXAMETHYLENE DIISOCYANATE HOMOPOLYMERS (HDI-IC AND HDI-BT): Results of Subacute and Subchronic Repeated Inhalation Exposure Studies |journal=Inhalation Toxicology |volume=13 |issue=6 |pages=513–532 |doi=10.1080/08958370118600 |pmid=11445890 |s2cid=13505170 |issn=0895-8378}}{{Cite journal |last1=Wisnewski |first1=Adam V. |last2=Liu |first2=Qing |last3=Miller |first3=Jing-Jing |last4=Magoski |first4=Nadine |last5=Redlich |first5=Carrie A. |date=2002-09-01 |title=Effects of hexamethylene diisocyanate exposure on human airway epithelial cells: in vitro cellular and molecular studies. |journal=Environmental Health Perspectives |volume=110 |issue=9 |pages=901–907 |doi=10.1289/ehp.02110901 |pmc=1240990 |pmid=12204825}}
See also
References
External links
- [https://www.cdc.gov/niosh/topics/isocyanates/ NIOSH Safety and Health Topic: Isocyanates], from the website of the National Institute for Occupational Safety and Health (NIOSH)
- [https://www.cdc.gov/niosh/npg/npgd0320.html NIOSH Pocket Guide to Chemical Hazards - Hexamethylene diisocyanate ]