Does the metal complexing of crown ether influence its reactivity?

I am conducting a SN2 reaction experiment with 1-aza-18-crown-6 and bromide compound. I used 1 equivalent of bromide compound and 1.1 equivalent of aza crown, but in the TLC plate the aza crown spot disappeared and the bromoide compound spot still showed. I used Na2CO3 as base, and KI as catalyst. Similar papers use NaI, but our lab doesn't have it, I thought that KI can act in similar way. Recently I found that 1-aza-18-crown-6 can form complex with potassium ion. So with the incomprehensible result in spite of the excess amount of the aza crown, I wonder if the complex of the potassium ion and the aza crown doesn't participate in the SN2 reaction anymore.


