Reaction #1375818

Reaction equation

1,4,7-tris-(carboxymethyl)-1,4,7,10-tetraazacyclododecane

2-methoxyethyl bromide

potassium carbonate

→

title compound

Yield 71.1%

10-(3-Oxa-butyl)-1,4,7-tris-(carboxymethyl)-1,4,7,10-tetraazacyclododecane

Yield 71.1%

Solvents

dimethylformamide

Conditions

Workup

1. 1
   ConcentrationIt is concentrated by evaporation in a vacuum
2. 2
   Otherevaporated to dryness
3. 3
   TemperatureThe residue is refluxed with 200 ml of methanol
4. 4
   Filtrationthe undissolved material is filtered out
5. 5
   Otherit is evaporated to dryness in a vacuum
6. 6
   workup.DISSOLUTIONthe residue is dissolved in 50 ml of water
7. 7
   WashIt is eluted first with 0.5 l of water, which
8. 8
   WashThen, it is eluted with 0.5 l of 0.5 N ammonia solution
9. 9
   OtherIt is evaporated almost to dryness in a vacuum
10. 10
    workup.ADDITIONmixed with 100 ml of water and enough cation exchanger IRC 50
11. 11
    workup.ADDITIONis added
12. 12
    FiltrationThe solution is then filtered
13. 13
    Otherfreeze-dried

Procedure

3 g (8.66 mmol) of 1,4,7-tris-(carboxymethyl)-1,4,7,10-tetraazacyclododecane is stirred in 50 ml of dimethylformamide for 10 hours with 1.57 g (11.29 mmol) of 2-methoxyethyl bromide and 4.15 g of potassium carbonate at 90° C. It is concentrated by evaporation in a vacuum and the residue is spread between 100 ml of water and 50 ml of diethyl ether. The aqueous phase is adjusted to pH 2 with 5 N hydrochloric acid and evaporated to dryness. The residue is refluxed with 200 ml of methanol, the undissolved material is filtered out, it is evaporated to dryness in a vacuum, the residue is dissolved in 50 ml of water, adjusted to pH 2 with 5 N hydrochloric acid and the solution is put on a column with 200 ml of cation exchanger IRC 50. It is eluted first with 0.5 l of water, which is discarded. Then, it is eluted with 0.5 l of 0.5 N ammonia solution. It is evaporated almost to dryness in a vacuum, mixed with 100 ml of water and enough cation exchanger IRC 50 is added with stirring until pH 3.5 is reached. The solution is then filtered and freeze-dried. 2.49 g of the title compound with a water content of 4.30% is obtained.

Source