Method for the production of isocyanatoorganosilanes

1. A process for preparing isocyanatoorganosilanes comprising thermolysis of carbamatoorganosilanes in a reactor, wherein the thermolysis takes place in the liquid phase with exposure to microwave radiation, volatile reaction products are removed from the reactor, and an isocyanatoorganosilane product is isolated from the reaction products.

2. The process of claim 1 , wherein isocyanatoorganosilanes of the formula (1) are prepared

R 2 R 3 R 4 Si—R 1 —N═C═O  (1),

where

R 1 is a divalent C 1 -C 6 -hydrocarbon radical and R 2 , R 3 and R 4 are in each case independently of one another, a methyl, ethyl, n-propyl, isopropyl, methoxy, ethoxy, n-propoxy or isopropoxy radical, by thermolysis of carbamatoorganosilanes of the formula (2)

R 2 R 3 R 4 Si—R 1 —NH—CO—OR  (2),

where

R is a monovalent C 1 -C 10 -alkyl radical.

3. The process of claim 1 , wherein the thermolysis takes place in the presence of a catalyst.

4. The process of claim 1 , wherein no catalyst is present.

5. The process of claim 3 , wherein the catalyst is a homogeneous catalyst.

6. The process of claim 5 , wherein the catalyst comprises one or more compounds selected from the group consisting of soluble compounds of tin, lead, cadmium, antimony, bismuth, titanium, zirconium, niobium, iron, cobalt, manganese, chromium, molybdenum, tungsten, nickel, copper, zinc, and soluble organic nitrogen bases.

7. The process of claim 5 , wherein the catalyst comprises one or more compounds selected from the group consisting of 1,4-diazabicyclo[2.2.2]octane, dibutyltin dilaurate, dibutyltin maleate, dibutyltin diacetate and dimethyltin dichloride.

8. The process of claim 3 , wherein the catalyst is a heterogeneous catalyst.

9. The process of claim 8 , wherein the catalyst comprises a metal or compound thereof, the metal selected from the group consisting of Sn(I), Sn(II), Pb(II), Zn(II), Cu(I), Cu(II), Co(I), Co(II), Na, K, Li, Rb, Cs, Sr, Ba, Mg, Ca, Cr, Mo, Ti, V, W, Ce, Fe, Ni, Si, Al, Ge, Ga, In, Sc, Y, La and lanthanides, Pd, Pt, Co, Rh, Cu, Ag, Au, Zn, Cr, Mo, W, Cd, Fe, N, O, B, C, and mixtures and alloys containing the abovementioned elements.

10. The process of claim 8 , wherein the catalyst comprises at least one oxide, hydroxide, oxyhydroxide, mixed oxide, acetate, formate, oxalate, tartrate, citrate, nitrate, carbonate, or mixtures of the above-mentioned compounds, of one or more elements selected from the group consisting of Sn(I), Sn(II), Pb(II), Zn(II), Cu(I), Cu(II), Co(I), Co(II), Na, K, Li, Rb, Cs, Sr, Ba, Mg, Ca, Cr, Mo, Ti, V, W, Ce, Fe, Ni, Si, Al, Ge, Ga, In, Sc, Y, La and lanthanides, Pd, Pt, Rh, Ag, Au and Cd.

11. The process as claimed in claim 8 , wherein the catalyst comprises one or more compounds selected from the group consisting of TiO 2 , ZrO 2 , HfO 2 , Al 2 O 3 , BaO, CaO, MgO, CeO 2 , La 2 O 3 , Y 2 O 3 , Sm 2 O 3 , Yb 2 O 3 , Cr 2 O 3 , ZnO, V 2 O 4 , MnO 2 , NiO, In 2 O 3 , Ga 2 O 3 , GeO 2 , FeO, Fe 2 O 3 , Fe 3 O 4 , CuO, Co 3 O 4 , Fe(MoO 4 ) 3 , MgO/CsOH, MgO/NaOH, aluminosilicates, zeolites, cordierite of the composition 2MgO.2Al 2 O 3 .5SiO 2 , heteropolyacids, carbon, transition metal nitrides, transition metal borides, transition metal silicides and carbides.

12. The process of claim 8 , wherein the catalysts are provided on a support.

13. The process of claim 12 , wherein as a catalyst support, an inert refractory material is employed.

14. The process of claim 11 , wherein as a catalyst support, oxidic and nonoxidic ceramics, SiO 2 , carbon, aluminosilicates, magnesium aluminosilicates or resistant metallic materials are used.

15. The process of claim 11 , wherein catalyst supports are in the form of irregular granules, spheres, rings, half-rings, saddles, cylinders, trilobes, or monoliths.

16. The process of claim 1 , wherein a gas-phase reactor containing a heterogeneous catalyst is located downstream of the microwave reaction chamber.