Mixed C4s, also known as Crude C4, Raffinate 1 or Raffinate 2, are colorless gases (liquid under pressure), with a mild, petroleum-like odor. Raffinate 1 is the product remaining when butadiene is extracted from a lower olefin stream (known as crude C4). Raffinate 1 is a mixture of butenes (iso-butenes and n butenes) with butane and residual butadiene. Raffinate 2 is produced from Raffinate 1 after iso butenes have been extracted. It consists of a mixture of n-butenes, butane and potentially some residual butadiene.