N- 2-Mercaptoethyl -3,5-dimethylpyrazole

Submitted by ELISABETH BOUWMAN and JAN REEDIJK Checked by JEEHEE KANG and MARCETTA Y. DARENSBOURGT 

The preparation of N-(2-p-toluenesulfonylethyl)-3,5-dimethylpyrazole is described elsewhere in this volume.5 l,l,3,3-Tetramethyl-2-thiourea and other reagents are available from the usual commercial sources. 

The synthesis of N-(2-mercaptoethyl)-3,5-dimethylpyrazole and the workup procedure are performed in air, but the resultant thiol can best be stored under a nitrogen atmosphere. In air, the thiol is resistant to oxidation for several weeks, but the disulfide slowly crystallizes from the oil. According to the NMR spectra, the product is quite pure, but may still contain a small amount of 1,1,3,3-tetramethylurea (up to 5%). The reaction with 1,3-dichloro-2-propanol was carried out in a water/tetrahydrofuran mixture with sodium hydroxide, and appeared to proceed smoothly and in almost quantitative yields.2 This new reaction path to pyrazole-thioether ligands opens the road to the development of new chelating ligands. 

5-DIAZACYCLOOCTANE, PENDANT ARM THIOLATO DERIVATIVES AND [7V,7V-BIS(2-MERCAPTOETHYL)-l,5-DIAZAC Y CLOOCTAN ATO]NICKEL(II) 

Checked by ROBERT D. HANCOCK,f SHEILA ENG, and ARTHUR E. MARTELL  

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