Tetramethylxylylene diisocyanate
{{Chembox
| ImageFile = TMXDI v2.svg
| ImageClass = skin-invert-image
| ImageSize = 200px
| ImageAlt =
| PIN = 1,3-Bis(2-isocyanatopropan-2-yl)benzene
| OtherNames =
|Section1={{Chembox Identifiers
| CASNo = 2778-42-9
| PubChem = 17719
| EC_number = 220-474-4
| UNII = YMD74QL0TC
| ChEMBL = 3183020
| ChemSpiderID = 16747
| StdInChI=1S/C14H16N2O2/c1-13(2,15-9-17)11-6-5-7-12(8-11)14(3,4)16-10-18/h5-8H,1-4H3
| StdInChIKey = AZYRZNIYJDKRHO-UHFFFAOYSA-N
| SMILES = CC(C)(C1=CC(=CC=C1)C(C)(C)N=C=O)N=C=O
}}
|Section2={{Chembox Properties
| C=14|H=16|N=2|O=2
| MolarMass =
| Appearance = Colorless liquid
| Density = 1.06 g/cm3
| MeltingPtC = -10
| MeltingPt_notes =
| BoilingPt =
| Solubility = }}
|Section3={{Chembox Hazards
| GHSPictograms = {{GHS05}}{{GHS07}}{{GHS08}}{{GHS09}}
| GHSSignalWord = Danger
| HPhrases = {{H-phrases|315|317|319|330|334|335|372|410}}
| PPhrases = {{P-phrases|260|261|264|270|271|272|273|280|284|285|302+352|304+340|304+341|305+351+338|310|312|314|320|321|332+313|333+313|337+313|342+311|362|363|391|403+233|405|501}}
| MainHazards =
| FlashPt =
| AutoignitionPt = }}
}}
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.{{cite web |url=https://iaspub.epa.gov/sor_internet/registry/substreg/searchandretrieve/advancedsearch/externalSearch.do?p_type=CASNO&p_value=2778-42-9 |title=m-Tetramethylxylene diisocyanate |publisher=United States Environmental Protection Agency |website=iaspub.epa.gov |access-date=2018-11-02 |archive-url=https://web.archive.org/web/20181106004857/https://iaspub.epa.gov/sor_internet/registry/substreg/searchandretrieve/advancedsearch/externalSearch.do?p_type=CASNO&p_value=2778-42-9 |archive-date=2018-11-06 |url-status=live }}{{cite web |url=https://pubchem.ncbi.nlm.nih.gov/compound/1_3-bis_1-isocyanato-1-methylethyl_benzene |title=1,3-Bis(1-isocyanato-1-methylethyl)benzene |publisher=National Center for Biotechnology Information, U.S. National Library of Medicine |website=pubchem.ncbi.nlm.nih.gov |access-date=2018-10-23 |archive-url=https://web.archive.org/web/20181106005040/https://pubchem.ncbi.nlm.nih.gov/compound/1_3-bis_1-isocyanato-1-methylethyl_benzene |archive-date=2018-11-06 |url-status=live }}{{cite web |url=https://pubchem.ncbi.nlm.nih.gov/compound/21908508#section=Top |title=Tetramethylxylene diisocyanate |publisher=National Center for Biotechnology Information, U.S. National Library of Medicine |website=pubchem.ncbi.nlm.nih.gov |access-date=2018-11-02 |archive-url=https://web.archive.org/web/20181106004907/https://pubchem.ncbi.nlm.nih.gov/compound/21908508#section=Top#section=Top |archive-date=2018-11-06 |url-status=live }} TMXDI is generally classified as an aliphatic isocyanate, which are generally more UV stable than their aromatic counterparts.
Production
Many isocyanates are produced by phosgenation of amines, but TMXDI is not. It is produced by the reaction of diisopropenylbenzene with hydrogen chloride followed by isocyanic acid:{{Ullmann |author=Christian Six |author2=Frank Richter |title=Isocyanates, Organic |year=2005 |doi=10.1002/14356007.a14_611}}
:C6H4(C(Me)=CH2)2 + 2 HCl → C6H4(CMe2Cl)2
:C6H4(CMe2Cl)2 + 2 HNCO → C6H4(CMe2NCO)2 + 2 HCl
Uses
A key use for TMXDI is in manufacturing polyurethane prepolymers. It is also used to manufacture polyurethane dispersions (PUDs).{{Cite web
| url = https://slideheaven.com/oxazolidines-and-tetramethylxylenediisocyanate-based-polyurethanes-in-legislatio.html
| title = Oxazolidines and tetramethylxylenediisocyanate based polyurethanes in legislation-compliant anticorrosion coatings – PDF Free Download
| website = slideheaven.com
| language = en
| access-date = 2018-10-23
| title = Aqueous polyurethane dispersion and method for making and using same
| country = US
| number = 7342068
| inventor=Eric Howard Klingenberg
| inventor2= Shafiq Nisarali Fazel
| assign1=Versum Materials US LLC
| issue-date = 2003-11-18
| url = https://www.european-coatings.com/Editorial-archive/Aqueous-PUDs
| title = Aqueous PUDs
| last = KG
| first = Vincentz Network GmbH & Co.
| website = European Coatings
| language = en-GB
| access-date = 2018-10-23
|last1 = Howarth
|first1 = G A
|last2 = Manock
|first2 = H L
|date = July 1997
|title = Water-borne polyurethane dispersions and their use in functional coatings
|journal = Surface Coatings International
|language = en
|volume = 80
|issue = 7
|pages = 324–328
|doi = 10.1007/bf02692680
|s2cid = 137433262
|issn = 1356-0751
| url = https://www.linkedin.com/pulse/water-based-polyurethanes-dispersionspuds-an-overview-nikhil-gupta/
| title = Water Based Polyurethanes Dispersions(PUDs)-An Overview
| website = www.linkedin.com
| language = en
| access-date = 2018-10-23
}} These materials are then further used to manufacture coatings, adhesives, sealants and elastomers.
TMXDI has been considered as a replacement for Isophorone diisocyanate (IPDI). IPDI has a molecular weight of 222.3 and thus a NCO equivalent weight of 111.15. TMXDI has a molecular weight of 244.3 and thus an equivalent weight of 122.15. Thus per mole, approximately 10% more is required than the equivalent prepolymer based on IPDI. This difference increases cost.When making polyurethanes dispersions (PUDs) TMXDI is advantageous. Being sterically hindered, the NCO groups are slower reacting which is good when dispersing a prepolymer in water to make a PUD. It reduces side reactions and allows more time to allow the dispersion stage before the mix is chain extended. This is done usually with a diamine.{{Cite web
| url = https://www.palmerholland.com/Assets/User/Documents/Product/40848/5070/MITM00579.pdf
| title = TMXDI Technical Bulletin
}} It has even found use in a rocket propellant binder by the US military.{{Cite patent|title=TMXDI, curing agent for hydroxy terminated propellant binders |country=US|number=4913753|issue-date=Apr. 3, 1990|inventor=Marjorie E. Ducote|assign1=The United States of America as represented by the Secretary of the Army, Washington, D.C.}}
Safety
Extensive data has become available.{{Cite web
|url = https://pubchem.ncbi.nlm.nih.gov/compound/1_3-bis_1-isocyanato-1-methylethyl_benzene#section=Top
|title = 1,3-Bis(1-isocyanato-1-methylethyl)benzene
|last = Pubchem
|website = pubchem.ncbi.nlm.nih.gov
|language = en
|access-date = 2018-10-23
|archive-url = https://web.archive.org/web/20181106005040/https://pubchem.ncbi.nlm.nih.gov/compound/1_3-bis_1-isocyanato-1-methylethyl_benzene#section=Top#section=Top
|archive-date = 2018-11-06
|url-status = live
}}
See also
References
{{Reflist}}
External links
- [https://www.palmerholland.com/Assets/User/Documents/Product/40848/5070/MITM00579.pdf Technical Data Sheet TMXDI]
- [https://www.palmerholland.com/Assets/User/Documents/Product/40845/3050/MITM00576.pdf Safety Data Sheet TMXDI]
- [https://incorez.com/ Incorez website]