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19th March 2018 @ 15:11

Method

2-chloro-6-hydrazinopyrazine (A) (101.0 mg, 0.70 mmol, 1.00 equiv.) was partially dissolved in EtOH (10 mL) forming a yellow solution. 4-chlorobenzaldehyde (B) (105.0 mg, 0.75 mmol, 1.1 equiv.) was then added causing full dissolution. The yellow solution was stirred for five minutes at room temperature before a pale yellow solid precipitated out of the reaction mixture. The reaction was stirred for a further 2.5 hours and was monitored by TLC (3:7 Ethyl acetate : PET ether)* until completion. The solid was filtered under vacuum to give 2-chloro-6-(2-hydrazinyl(4-chlorobenzylidene))pyrazine) as a pale yellow powder (103.9 mg, 56.5 %). This was characterised by IR and 1HNMR. The filtrate was also recovered in vacuo and characterised by IR and 1HNMR but excess 4-chlorobenzaldehyde starting material was also present so an accurate yield could not be determined.

*4-chlorobenzaldehyde is unstable to TLC (see 2DTLC).


Attached Files
19:3-2.png
TLC diagram at 2 hr 25 mins in 3to7 EtOAc to PET ether(4-chloro).png
TLC at 2h, 25mins in 3to7 Ethyl acetate to PET ether (4-chloro).png
Reaction mixture at 5 mins (4-chloro).png
2DNMR determining that 4-chlorobenzaldehyde is unstable to TLC in 3to7 Ethyl acetate to PET ether.png