Diisocyanates 2,6-TDI

Up to this point we have discussed only carbamates la-4a with a single carbamate group on the phenyl ring as model systems for aromatic polyurethane photodecomposition. In polyurethane coatings based on the aromatic diisocyanate TDI two carbamate groups are attached to the phenyl ring. Furthermore commercially available TDI is actually a mixture of 2,4-toluene diisocyanate (2,4-TDI) and 2,6-toluene diisocyanate (2,6-TDI) which when formulated give 2,4- and 2,6-biscarbamates. Model systems for these species would then be biscarbamates of 2,4-TDI and 2,6-TDI (as shown below) and not carbamates such as la-4a. 

Synonyms AI3-015101 BRN 0744602 CCRIS 3742 Desmodur T80 2,4-Diisocyanato-l-methylbenzene Diisocyanatoluene 2,4-Diisocyanotoluene Hylene T Hylene TCPA Hylene TLC Hylene TM Hylene TM-65 Hylene TRF Isocyanic acid, methylphenylene ester Isocyanic acid, 4-methyl-/ 3-phenylene ester 4-Methylphenylene diisocyanate 4-Methylphenylene isocyanate Mondur TD Mondur TD-80 Mondur TDS Nacconate 100 NCI-C50533 Niax TDI Niax TDI-P NSC 4791 NSC 56759 RCRA waste number U223 Rubinate TDI 80/20 TDI 2,4-TDI TDI-80 Toluene 2,4-diisocyanate Tolyene-2,4-diisocyanate Tolylene-2,4-diisocyanate 2,4-Tolylene diiso-cyanate /n-Tolylene diisocyanate UN 2078. 

Toluene 2,4-Diisocyanate (Tolylene diisocyanate, 2,4-Diisocyanotoluene, TDI, Nacconate 100, or Metatolylene diisocyanate). 

Asymmetric diisocyanates such as 2,4-TDI are more complex because the initial reactivity of the two isocyanate groups is not equivalent and the substitution effect amplifies the difference. The 4-NCO is about 10-20 times more reactive than the 2-NCO, but the reactivity ratio also depends on temperature (see Chapter 5). This difference also explains why the TDI dimer can be prepared quantitatively (Eq. 2.28). 

The velocity constant of 1,5 naphthalene diisocyanate, where both NCO groups are equal on the ring, is the same. The velocity constants of the 2,4 TDI are quoted by Saunders and Frisch (Saunders, 1962) as being k, = 42.5 and k2 = 1.6. The 2,6 isomer of TDI has velocity constants of kj = 5 and k2 = 2. This indicates that the initial reaction will be fastest with the 2,4 isomer at the 2 position. See Figure 2.16 for position numberings. 

Toluene Diisocyanate (TDI) Toluene diisocyanates (2,4- and 2,6 isomers) are produced from toluene diamine derived from dinitrotoluene, which is produced by the nitration of toluene with nitric/sulfuric acid mixtures. TDI is used to make flexible polyurethane foams, elastomers and coatings. 

Above the -relaxation process, the 2,4-TDI/PTMO polymer displayed a short rubbery plateau at a storage modulus of about 5 MPa while 2,6-TDI/PTMO was capable of crystallization, as evidenced by the ac-loss process. This difference in dynamic mechanical properties demonstrates the effect of a symmetric diisocyanate structure upon soft-segment properties. As previously discussed, single urethane links can sometimes be incorporated into the soft-segment phase. The introduction of only one of these diisocyanate molecules between two long PTMO chains inhibits crystallization if the diisocyanate is asymmetric. In the case of a symmetric diisocyanate, soft-segment crystallization above Tg can readily occur. The crystals formed were found to melt about 30°C below the reported melting point for PTMO homopolymer, 37°-43°C (19), possibly because of disruption of the crystal structure by the bulky diisocyanate units. 

Synonyms and trade names toluene-2,4-diisocyanate, 2,4-diisocyanato-l-methylbenzene, diiso-cyanatotoluene, TDI, creorcinol diisocyanate, m-tol-uene diisocyanate, 4-methyl-l,3-phenylene diisocyanate. 

Also, selective reaction of the para isocyanate group in 2,4-TDI 59 is observed using a phospholene oxide catalyst to form the diisocyanate 60, mp 113-115... 

Polyhexamethylenecarbodiimide, an insoluble condensation reagent for the synthesis of peptides, is obtained in the reaction of hexamethylene diisocyanate with a phospholene oxide catalyst in NMP. The isocyanate end groups are reacted with ethanol. Linear polycarbodiimides, upon reaction with adipic acid, form polyureides. For example, reaction of the 2,4-TDI derived carbodiimide with adipic acid in DMF produces the polymer, mp295°C.222... 

When the less hindered 2,4-tolylene diisocyanate is reacted with a phospholene oxide catalyst linear oligomeric carbodiimides are obtained which have been reacted with a variety of nucleophiles to give poly(ureas), poly(acyl ureas), poly(formamidines) and poly-(guanidines) by addition across the N=C=N group. Also, reaction of the oligomeric carbodiimides with acrylic or methacrylic acid affords linear polymers, which can be further polymerized by free-radical type processes. Also, reaction of the carbodiimide oligomers obtained from 2,4-TDI with adipic acid in DMF produces a polyureid. ... 

BuOH = 1-butanol, EG = ethylene glycol, ETOH = 2-ethoxyethanol, EtSOH = 2-ethylthioethanol, DMAOH = j6-dimethylaminoethanol, HEAC = 2-hydroxyethyl acetate, NPG = neopentylglycol. Toluene diisocyanate prepolymer (80% 2,4-TDI 20% 2,6-TDI) 91 %, trimethy-lolpropane 9 %... 

Isocyanate Components. Aromatic Di- and Polyisocyanates. The most important monomeric aromatic diisocyanates used for coatings are tolylene diisocyanate (TDI) and 4,4 -methylene bis(phenyl isocyanates) (MDI). Tolylene diisocyanate, a colorless liquid (bp 120 °C at 10 mmHg), is generally used in 80/20 blends of the 2,4-and 2,6-lsomers. Pure 2,4-TDI isomer has also been employed for coatings. 

Toluene 2,4-Diisocyanate. 2,4-Di isocyan atotolu -ene 2.4-tolylene diisocyanate TDI Nacconate 100, CjH -NjOj mol wt 174.15. C 62.07%, H 3.47%, N 16.09%, O 18.37%. Usually prepd from toluene-2,4-diamine and phosgene. Review Astle, Industrial Organic Nitrogen Compounds (New York, 1961) pp 284-313 Faith, Keyes Clark s Industrial Chemicals, F. A. Lowenheim, M. K. Moran, Eds. (Wiley -lntersdenee, New York, 4th ed., 1975) pp 831-835. 

Benzene, 1,3 Jiisocyanatomethyl- CCRIS 596 Desmodur T 80 Desmodur T100 Diisocyanatotoluene 1,3-Diisocyanatomethylbenzene EINECS 247-722-4 HSDB 6003 Isocyanic acid, methyl-m-phenylene ester Methyl-m-phenylene isocyanate Methylphenylene isocyanate Mondur TD-80 Nacconate-lOO Niax iso-cyanate TDI RCRA waste number U223 Rubinale TDI Rubinate TDI 80/20 TDI TDI 80-20 Toluene-2,4-diisocyanate (mixt. with Toluene-2,6-diisocyanate) Toluene diisocyanate 2,4/2,6-Toluene diisocyanate iso-meric mixture 2,4-Toluene diisooyanate 2,4- and 2,6-Toluene diisocyanate Toluenediisocyanate (mixed isomers) Tolylene diisocyanate Tolylene isocyanate m-Tolylidene diisocyanate UN 2078. Mixture of... 

The current state of the art involves the use of piperazine compounds which react with diisocyanates to form electrochemically detectable or fluorescent urea derivatives (Eickeler, 1990 Warwick et al., 1981 Schmidtke and Seifert, 1990 Brown et al., 1987 Bagon et al., 1984 Ellwood et al., 1981). Two OSHA methods (nos. 42 and 47) (OSHA, 1989a OSHA, 1989h) describe a derivatization with l-(2-pyridyl)-piper-azine (2PP) to l,6-bis-[4-(2-pyridyl)-l-piperazine-carbamyl]-hexane (HDI-2PP), 2,6-bis-[4-(2-pyridyl)-1 -piperazine-carbamyl]-toluene (2,6-TDI-2PP), 2,4-bis-[4-(2-pyri-dyl)-l-piperazine-carbamyl]-toluene (2,4-TDI-2PP) and N,N -(methylenedipheny-lene)-bis-4-(2-pyridinyl)-l-piperazine-carboxamide (MDI-2PP) on a coated filter, using the combination HPLC/fluorescence for separation and detection, respectively. 

Synonyms 2,4-tolylene diisocyanate 2,4-diisocyanatotoluene toluene diisocyanate (TDI) 4-methyl phenylene diisocyanate isocyanic acid 4- methyl-m-pheny lene ester... 

Alternative Names/Abbreviations Toluene diisocyanate, two isomers 2,4-TDI and2,6-TDI 2,4-diisocyanato-1-methyl-benzene, TDI... 

CAS 584-84-9 EiNECS/ELiNCS 209-544-5 UN 2206 (DOT) UN 2207 (DOT) UN 2478 (DOT) UN 3080 (DOT) Synonyms Diisocyanatoiuene 2,4-Diisocyanato-1-methyibenzene 2,4-Diisocyanatotoiuene isocyanic acid, methyiphenyiene ester isocyanic acid, 4-methyi-m-phenyiene ester 4-Methyiphenyiene diisocyanate 4-Methyiphenyiene isocyanate TDi 2,4-TDi Toiuene diisocyanate 2,4-Toiuenediisocyanate Toiuyiene-2,4-diisocyanate Toiyiene diisocyanate 2,4-Toiyiene diisocyanate m-Toiyiene diisocyanate CiassKication isocyanic acid ester Empiricai CgHsNjOj Formuia CH3C6H3(NCO)2... 

TDI. See Toluene-2,4-diisocyanate 2,6-TDI. See Toluene-2,6-diisocyanate TDI 80-20. See Toluene diisocyanate TDM TDM. Seet-Dodecyl mercaptan TDMAMP. See2,4,6-Tris (dimethylaminomethyl) phenol... 

For both polyurethanes and polyurethaneureas, the molar ratio of 2,4 TDI, butanediol (or ethylene diamine) and PTMO was varied in five equal steps from 2 1 1 to 6 5 1. For polyurethanes, 5% excess diisocyanate was used while for polyurethaneureas, the exact stoichiometry was used. 

Toluene diisocyanate has two common isomers the 2,4- and 2,6-TDI. The most commonly supplied TDI is a combination of 80% 2,4- and 20% 2,6-TDI. A 65/35 ratio of the 2,4-/2,6-TDI is also available, as well as a 100% 2,4-TDI product. The reactivity of the two isocyanates on TDI is different. Once the first isocyanate has reacted, the second is roughly eight times less reactive [21], TDI produces lower-viscosity prepolymers than does MDI. Pure 4,4 -MDI has a reactivity difference between the isocyanates of approximately 2/1 [22]. 

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