( 1 ) CH₄ → CH ≡ CH + 2H₂ ( đk : lln, 1500 độ C )

( 2 ) 2CH ≡ CH → CH ≡ C - CH = CH₂

( 3 ) CH ≡ C - CH = CH₂ + H₂ → CH₂ = CH - CH = CH₂ ( đk : Ni, t độ )

( 4 ) _nCH₂ = CH - CH = CH₂ → ( - CH₂ - CH = CH - CH₂ - )_n ( đk : xt, t độ, P )

Sơ đồ điều chế:

$\rm CH_4 \xrightarrow{(1)} C_2H_2 \xrightarrow{(2)} CH\equiv C-CH=CH_2 \xrightarrow{(3)} CH_2=CH-CH=CH_2 \xrightarrow{(4)} (\kern-6pt-CH_2-CH=CH-CH_2-\kern-6pt)_n$

$(1)\quad \rm 2CH_4 \xrightarrow[\text{làm lạnh nhanh}]{1500^\circ C} C_2H_2 + 3H_2$

$(2)\quad \rm 2CH\equiv CH \xrightarrow{150^\circ C,\ CuCl} CH\equiv C-CH=CH_2$

$(3)\quad\rm CH\equiv C-CH=CH_2 + H_2 \xrightarrow{t^\circ,\ Pd/PbCO_3} CH_2=CH-CH=CH_2$

$(4)\quad\rm nCH_2=CH-CH=CH_2 \xrightarrow{t^\circ,\ xt,\ p} (\kern-6pt-CH_2-CH=CH-CH_2-\kern-6pt)_n$