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Hydrocarbons: Alkanes formula sheet

Every formula in the Hydrocarbons: Alkanes chapter for JEE Main, with one line on when it applies. Topic 1 is open to everyone; sign in free to read all 11 and download the PDF.

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Preparation of alkanes

Wurtz and Kolbe
1× asked, last 2025
2 RX+2 Na→dry etherR−R+2 NaX (Wurtz)2 RCOONa+2 HX2O→electrolysisR−R+2 COX2+HX2+2 NaOH (Kolbe)\begin{aligned}&\ce{2RX + 2Na ->[\text{dry ether}] R-R + 2NaX}\ (\text{Wurtz})\\&\ce{2RCOONa + 2H2O ->[\text{electrolysis}]}\\&\quad\ce{R-R + 2CO2 + H2 + 2NaOH}\ (\text{Kolbe})\end{aligned}
R–R only, never CHX4\ce{CH4}. One RX gives an even-C alkane; two different RX give three alkanes.
Decarboxylation and reduction
RCOONa+NaOH→ΔCaORH+NaX2COX3 (one C fewer)RX→Zn, dil. HClRH,RX→Mg, etherRMgX→HX2ORHRC≡CH→HX2/Pt, Pd, NiRCHX2CHX3\begin{aligned}&\ce{RCOONa + NaOH ->[\text{CaO}][\Delta] RH + Na2CO3}\ (\text{one C fewer})\\&\ce{RX ->[\text{Zn, dil. HCl}] RH},\qquad \ce{RX ->[\text{Mg, ether}] RMgX ->[H2O] RH}\\&\ce{RC#CH ->[\ce{H2}/\text{Pt, Pd, Ni}] RCH2CH3}\end{aligned}
Reduction keeps the C count; Zn/HCl does not reduce RF.

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9 more formulas in 2 topics

Free-radical halogenation and Conformations and properties. Read the first part free. Sign in free with Google to read the rest and download the PDF.

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Free-radical halogenation

  • Mechanism2×
  • Selectivity3×
  • Counting products4×

Conformations and properties

  • Conformations of ethane
  • Conformations of n-butane
  • Boiling point1×
  • Combustion2×
  • Controlled oxidation
  • Isomerisation and aromatisation

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