In chemical separation terminology, the Raffinate is a product which has had a component or components removed. In Naphtha cracking process, Raffinate-1 or C4R1 refers to C4 residual obtained after separation of 1,3-butadiene from C4 Raffinate stream. C4R1, a side product in 1,3-butadiene plant is a flammable, colourless gas, with slight aromatic odour.
Raffinate-1 is fed as a raw material to isobutene production plant which in mixture with methanol, is used in MTBE production (methyl tertiary buthyl ether).