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The global market for diisocyanates in the year 2000 was 4.4 million tonnes, of which 61.3% was methylene diphenyl diisocyanate (MDI), 34.1% was toluene diisocyanate (TDI), 3.4% was the total for hexamethylene diisocyanate (HDI) and isophorone diisocyanate (IPDI), and 1.2% was the total for various others. [18]
The molecule consists of a phenyl ring attached to the isocyanate functional group. It is a colourless liquid that reacts with water. Phenyl isocyanate has a strong odor and tearing vapours, therefore it has to be handled with care. Characteristic of other isocyanates, it reacts with amines to give ureas. [2]
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. [3] This isomer is also known as Pure MDI. MDI reacts with polyols in the manufacture of polyurethane. It is the ...
Allyl thiocyanate isomerizes to the isothiocyanate: [4] CH 2 =CHCH 2 SCN → CH 2 =CHCH 2 NCS. Isothiocyanates can be prepared by treating organic dithiocarbamate salts with lead nitrate or tosyl chloride. [5] [6] Synthesis of phenyl isothiocyanate. Isothiocyanates may also be accessed by the fragmentation reactions of 1,4,2-oxathiazoles. [7]
For example, benzyl isocyanide has a pK a of 27.4 and benzyl cyanide has a pK a of 21.9, but toluene has a pK a in the 40s. [22] In the gas phase, CH 3 NC is 1.8 kcal/mol less acidic than CH 3 CN. [23] Chlorination of isocyanides gives isocyanide dichlorides.
Benzyl is most commonly abbreviated Bn. For example, benzyl alcohol can be represented as BnOH. Less common abbreviations are Bzl and Bz, the latter of which is ambiguous as it is also the standard abbreviation for the benzoyl group C 6 H 5 C(O)−. Likewise, benzyl should not be confused with the phenyl group C 6 H 5 −, abbreviated Ph.
Phenyl thiocyanate and phenyl isothiocyanate are isomers. Organic thiocyanates are organic compounds containing the functional group RSCN. the organic group is attached to sulfur: R−S−C≡N has a S–C single bond and a C≡N triple bond. [1] Organic thiocyanates are valued building blocks.
A blocked isocyanate can be added to materials that would normally react with the isocyanate such as polyols.They do not react at normal ambient room temperature. A formulation containing a blocked isocyanate is a single component material (and thus usually considered more convenient) but reacts like a two-component product but will not react until heated to the temperature required for ...