How will you bring about following conversions: (a) Methane to methanol (b) Ethane to ethanol (acetaldehyde) (c) Methane to methanoic acid
Answer
(a) Methane to methanol: $ 2 CH _4+ O _2 \xrightarrow[200^{\circ} C ]{ cu } 2 CH _3 OH $ (b) Ethane to ethanal(acetaldehyde): $ 2 C _2 H _6+ O _2 \xrightarrow[200^{\circ} Cu ]{ Cu } 2 C _2 H _5 OH $ $ C _2 H _5 OH \xrightarrow[\text { acidic }]{ K _2 Or _2 O _7} CH _3 CHO $ (c) Methane to methanoic acid: $ 2 CH _4+ O _2 \xrightarrow[200^{\circ} Cl ]{ Cu } 2 CH _3 OH $ $ CH _3 OH \xrightarrow[\text { acidic }]{ K _2 Or _2 O _7} HCHO \xrightarrow[\text { acidic }]{ K _2 Or _2 O _7} HCOOH $
$C _2 h _6+ CI _2 \xrightarrow{\text { UVlight }} C _2 H _5 CI + HCI$ $C _2 H _5 CI + CI _2 \longrightarrow C _2 H _4 CI _2+ HCI$ $C _2 H _4 CI _2+ CI _2 \longrightarrow C _2 H _3 CI _3+ HCI$ $C _2 H _3 CI _3+ CI _2 \longrightarrow C _2 H _2 CI _4+ HCI$ $C _2 H _2 CI _4+ CI _2 \longrightarrow C _2 HCI _5+ HCI$ $C _2 HCI _5+ CI _2 \longrightarrow C _2 CI _6+ HCI$
(a) What are products obtained when methane reacts with chlorine in diffused sunlight?
(b) Write the equation when methane reacts with chlorine in diffused sunlight.
(c) Name and define the type of above reaction.
Answer
(a) The products obtained when methane reacts with chlorine in diffused sunlight are Chloromethane, Dichloromethane, Trichloromethane and Tetrachloromethane.
(b)
$CH _4+ CI _2 \xrightarrow[\text { or } \Delta]{\text { UV light }} CH _3 Ci + HCI $
$CH _3 CI + CI _2 \longrightarrow CH _2 CI _2+ HCI $
$CH _2 CI _2+ CI _2-\cdot CHCi _3+ HCI$
$CHCI _3+ Ci _2 \longrightarrow CCI _4+ HCI$
(c) The above reaction is substitution reaction. Here the substitution of alkanes with chlorine takes place hence it is called chlorination.
The reactions in which the hydrogen of the alkane molecule is replaced by another atom or group of atoms resulting in the formation of the derivative of that hydrocarbon are called substitution reactions. Substitution by halogen atom is called halogenations.
What are the products obtained by heating ethane in: (a) Excess of air (b) Absence of air (c) Air in presence of copper and 120atm pressure (d) Air with molybdenum oxide at 100 atm pressure.
Answer
(a) Ethane reacts in excess of air to give carbon dioxide and water. $ 2 C _2 H _6+7 O _2 \longrightarrow 4 CO _2+6 H _2 O +\text { Heat } $ (b) Ethane reacts in absence of air to give carbon black. $ C _2 H _6+ O _2 \longrightarrow 2 C +3 H _2 O $ (c) Ethane reacts in presence of copper and $120 atm$ pressure to give ethanol $ 2 C _2 H _6+ O _2 \xrightarrow[200^{\circ} Cu ]{ Cu } 2 C _2 H _5 OH $ (d) Ethane reacts with molybdenum oxide at $100 atm$ pressure to give ethanal. $ C _2 H _6+ O _2 \xrightarrow[\Delta]{ MoO } CH _3 CHO + H _2 O $
