Oligomeric carbodiimides

A negative working photoresist system is obtained using a oligocarbodiimide derived from 2,4-TDI and a phospholene oxide catalyst. m-Tolylisocyanate is used as the chain stopper. To this soluble linear polycarbodiimide a photoamine is added, which generates 

6- dimethylpiperidine on irradiation. The generated secondary amine causes crosslinking via guanidine formation. 

Silicondicarbodiimide oligomers, [Si(NCN)2ln are obtained from silicon tetrachloride and bis(trimethylsilyl)carbodiimiide.  

Germaniumdicarbodiimide is obtained similarly from GeCl4 and bis(trimethylsilyl)-carbodiimide. Also, cyclic oligomers of dimesitylgermaniumcarbodiimide are obtained from dimesityldichlorogermanium and cyanamide in the presence of triethylamine or 

reaction of BCI3 with bis(trimethylsilyl)carbodiimide affords the corresponding boron carbodiimide oligomers. The reaction of borazine trichloride with bis(trimethylsilyl)carbodiimide affords crosslinked B/C/N oligomers 16.  

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The reaction of sterically hindered aromatic diisocyanates with bases or phospholene oxide catalysts afford oligomeric carbodiimides having terminal isocyanate groups. If the catalytic conversion of 4,4 -diphenylmethane diisocyanate (MDI) is conducted in the... 

Oligomeric carbodiimides are efficient stabilizers for polyesters or polyester containing polymers. 

Also, a high load soluble oligomeric carbodiimide is synthesized using the ROMP polymerization procedure (see Section 12.2). ... 

A 16 membered ring carbodiimide is obtained in the reaction of Me2SiCl2 with cyanamide." In addition to the tetramer, oligomers with n = 2 to 7 are detected. Also, higher oligomeric carbodiimides are formed in the reaction of alkyl- and dialkyl silicon chlorides with cyanamide in the presence of pyridine." Also, from bis(trimethylsilyl)carbodiimide and silicon tetrachloride in the presence of pyridine, the silicon polycarbodiimide 34 is obtained." ... 

Using highly hindered aromatic diisocyanates, such as 6, with a phospholene oxide catalyst produces oligomeric carbodiimides 7 ... 

Oligomeric carbodiimides are efficient stabilizers for polyester, polyester based polyurethanes, polyether based polyurethanes and polyether based poly(urethane ureas). Oligomeric carbodiimides are commercially available under the trade name Stabaxol from Rhein Chemie, a subsidiary of Bayer. 

In Table 12.1, the carbodiimides and oligomeric carbodiimides used in the stabilization of polyester based polymers are listed. ... 

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. ... 

Table 12.1 Carbodiimides and Oligomeric Carbodiimides Used as Stabilizers for Polyester Based Polymers...

High load, soluble oligomeric carbodiimides are obtained by ROM polymerization of N-cyclohexyl-N -(2-succinimidoethyl)carbodiimide 17 using a ruthenium catalyst to give 18,n = 50, 100 and 150.2°... 

The soluble oligomeric carbodiimide is used as a coupling reagent for esterification, ami-dation and dehydration of carboxylic acids. 

Hannig et al. (3) prepared carbodiimide- and uretoni mine-modified polyisocyanates using microwave radiation. These oligomeric isocyanates were subsequently used to prepare polyurethane articles. 

Also, oligomeric and polymeric carbodiimides are used extensively in solid state chemistry as shown in Chapter 12. 

Heating of isocyanates above 150 °C slowly produces carbodiimides. For example, heating of hexamethylene diisocyanate at 189-195 °C for 20 hr produced 4-6 % of oligomeric isocyanate terminated carbodiimides, but in addition 18-20 % of isocyanate terminated isocyanurates were formed. The reaction is facilitated if a slow stream of nitrogen is passed through the boiling isocyanate. The unsymmetrical isocyanate dimer 47 was proposed as an intermediate in this transformation. 

Unsaturated carbodiimides also undergo oligomerization reactions. An example is the cyclodimerization of dipyridyl-(2)-carbodiimide 37. This carbodiimide cannot be isolated because it undergoes dimerization via a [2+4] cycloaddition reaction to give the cyclodimer 38.5 ... 

The first synthesis of oligomeric dialkylsilyl carbodiimides 31 dates back to 1964, when Pump and Rochow reacted disilvercyanamide suspended in diethylether or benzene with dialkyldichlorosilanes 30 (R = Me, Ph, OEt R = Me, vinyl, Ph, OEt) the yields varied between 77 and 96 % and n varied between 6.4 and 8.4. ... 

The nucleophilic reactions of N-sulfurcarbodiimides are similar to the nucleophilic reactions of other carbodiimides. However, oligomerization reactions are less pronounced. The cyclic dimer of N-p-toluenesulfonyl-N -phenylcarbodiimide 31 is obtained on dissociation of the cycloadduct 30 obtained in the outlined reaction. " ... 

Several oligomeric metal carbodiimides are obtained from metal halides and salts of phenyl-cyanamide. Eor example, reaction of SbCE with KNCNPh 14 affords Sb(N=C=NPh)315, mp 271 °C (dec.) in 41 % yield. ... 

Likewise, borazene trichloride 17 reacts with bis(trimethylsilyl)carbodiimide to give 18, an oligomeric gel. ... 

Treatment of methylenechloride solutions of 1,3-diazacyclonona-l,2-diene and 1,3-diaza-cyclotetradeca-1,2-diene with a catalytic amount of tetrafluoroboric acid affords mixtures of dimeric and oligomeric species. From the seven membered ring tricyclic carbodiimide generated in the thermolysis of tetrazolophenanthridene only its cyclodimer has been isolated. 

Similar crosslinked oligomers are obtained from cyanuric halides and bis(trimethylsilyl)-carbodiimide. The oligomeric metal substituted carbodiimides are used as precursors for... 

The aza-Wittig reaction is also used to form polymers with pendant carbodiimide groups. For example, reaction of the polymeric azide 31 with benzyl isothiocyanate and triphenylphosphine gives the corresponding carbodiimide 32, a precursor for oligomeric guanidines." ... 

Poly(carbodiimides) are sometimes used as adhesive primers. Film forming carbodiimide homo- or copolymers have been used in microencapsulation techniques for pressure sensitive copy paper. Oligomeric acylureas are obtained from polyunsaturated carboxylic acids and carbodiimides as monomers for coatings. ... 

In the household-refrigerator industry, however, the one-shot process employing crude TDI (which has a lower percent NCO and contains oligomeric compounds, such as isocyanurate- and carbodiimide-types of oligomers) is still widely employed because of its low cost. 

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