Preparation of 11c methyl iodide

Abstract

A process for the preparation of 11 C methyl iodide comprises coating the internal surface of a first reaction vessel with a solution of lithium aluminium hydride, wherein the first reaction vessel has an internal diameter not greater than about 1.5 mm; introducing 11 C carbon dioxide into the first reaction vessel such that it is reduced by the lithium aluminium hydride to give a reduction product; and reacting the reduction product with hydriodic acid.

1 - 23 . (canceled) 
     
     
         24 . An apparatus for the production of  11 C methyl iodide, the apparatus comprising:
 a first reaction vessel ( 10 ) having an internal diameter not greater than about 1.5 mm and wherein the internal surface of said first reaction vessel has a coating of LiAlH 4 ;   a second reaction vessel ( 34 ) connected to the first reaction vessel ( 10 ), via a valve ( 28 ) which has a first and a second position such that when the valve ( 28 ) is in the first position, the first ( 10 ) and second ( 34 ) reaction vessels are not in fluid communication and when the valve ( 28 ) is in the second position the first ( 10 ) and second ( 34 ) reaction vessels are in fluid communication such that a mixture of hydriodic acid and a reduction product from the first reaction vessel ( 10 ) can pass from the first reaction vessel ( 10 ) into the second reaction vessel ( 34 ); and   means for heating the second reaction vessel ( 34 ).   
     
     
         25 . The apparatus of  claim 24 , wherein when the valve is in the first position, the first reaction vessel is connected to a waste line. 
     
     
         26 . The apparatus of  claim 24 , further comprising one or more of:
 means ( 15 ) for flushing out the first reaction vessel with nitrogen;   means for introducing  11 CO 2  ( 16 ) into the first reaction vessel;   means ( 20 ,  24 ) for introducing hydriodic acid into the first reaction vessel; and   means ( 40 ) for removing excess hydrogen iodide and water from the product.   
     
     
         27 . The apparatus of  claim 26 , wherein the means for flushing out the first reaction vessel with nitrogen comprises a connection to a nitrogen source ( 15 ). 
     
     
         28 . The apparatus of  claim 26 , wherein the means for introducing a solution of LiAlH 4  into the first reaction vessel comprises an injection system ( 26 ). 
     
     
         29 . The apparatus of  claim 26 , wherein the means for introducing  11 CO 2  into the first reaction vessel comprises a cryogenic trap ( 16 ) containing the  11 CO 2  a nitrogen source ( 15 ), means for mixing the  11 CO 2  from the trap with the nitrogen source and a first inlet tube ( 17 ) which carries the mixture of nitrogen and  11 CO 2  to the first reaction vessel. 
     
     
         30 . The apparatus of  claim 29 , wherein the nitrogen used to carry the  11 CO 2  and the nitrogen used for flushing out the first reaction vessel are taken from the same nitrogen source ( 15 ). 
     
     
         31 . The apparatus of  claim 26 , wherein the means for introducing hydriodic acid into the first reaction vessel comprises a hydriodic acid loop ( 20 ) through which flows a stream of nitrogen and means ( 24 ) for introducing hydriodic acid into the nitrogen stream. 
     
     
         32 . The apparatus of  claim 24 , wherein the second reaction vessel comprises a tube having an internal diameter of about 0.2-20 mm. 
     
     
         33 . The apparatus of  claim 24 , wherein the second reaction vessel ( 34 ) is constructed from a heat conducting material. 
     
     
         34 . The apparatus of  claim 24 , wherein the means for heating the second reaction vessel ( 34 ) comprises a block heater ( 36 ) surrounding the reaction vessel ( 34 ). 
     
     
         35 . The apparatus of  claim 24 , wherein the second reaction vessel ( 34 ) is in a generally vertical orientation. 
     
     
         36 . The apparatus of  claim 35 , wherein only the lower end of the second reaction vessel ( 34 ) is heated.