how to refine but-2-ynoic acid

i am synthesising this chemicasl but-2-ynoic aicd .

this chemical have three steps :

the first : 3-methylpyrazole -5-one

the second :44-dibromo-3-methylpyrazoble-5-one

the third : but-2-ynoic acid

now we have some question about third

the thrid produre:

prepare a solution of 20g sodium hydroxide in 500 ml water

and stire magnetically in an ice bath untile the tempreture

reach 0-5 degree ,add portionwise 34g of 44-dibromo-3-

methylpyrazoble-5-one .stir reaction mixture for 1 hour and

at room for 1 hour .acidified it with hydrochlroci acid . extract

reaction with ether ,and remove solvent and we will get

orange oil and allow to stand untile solidified ,

now we have two question :

first , which solvet can replace ether to extract , ether is

dangours in this season :

second : when we get oraner oil , which solvent we can add

in , and how to refine ,

thanks

look forward to reply .

[Edited on 24-7-2011 by romanceliu]