prov:value
| - Specific examples of suitable additive materials include (1) cyclic polyethers (crown ethers and oxygen-containing cryptands), wherein X is an oxygen atom, including (A) those wherein n is 4, such as (1) 1,4,7,10-tetraoxacyclododecane (12-crown-4) (Aldrich 19,490-5), of the formula ##STR18## (2) 2-(hydroxyethyl)-12-crown-4 (Aldrich 38,265-5), of the formula ##STR19## (3) 2-(aminoethyl)-12-crown-4
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