$RCH=CH_2 \xrightarrow{H_2/Ni} RCH_2CH_3$
$RC \equiv CH \xrightarrow{H_2/Ni} RCH_2CH_3$

Reduction of Carbonyl Compounds:

$RCHO \xrightarrow{H_2/Ni} RCH_2OH$
$RCOR' \xrightarrow{H_2/Ni} RCH(OH)R'$

Reduction of Nitriles to Primary Amines:

$RCN \xrightarrow{H_2/Ni} RCH_2NH_2$

Reduction of Nitro Compounds to Amines:

$RNO_2 \xrightarrow{H_2/Ni} RNH_2$

5. Oxidizing Agents

Potassium Permanganate ($KMnO_4$)
- Cold, dilute, alkaline ($Baeyer's Reagent$): Oxidizes alkenes to vicinal diols (syn addition).
  - $RCH=CH_2 \xrightarrow{cold, dil. KMnO_4} RCH(OH)CH_2OH$
- Hot, concentrated, acidic/alkaline: Cleaves C=C bonds, oxidizes alkanes at benzylic/allylic positions.
  - $RCH=CHR' \xrightarrow{hot, conc. KMnO_4} RCOOH + R'COOH$ (if H present on C)
  - $R_2C=CHR' \xrightarrow{hot, conc. KMnO_4} R_2C=O + R'COOH$
  - $R_2C=CR'_2 \xrightarrow{hot, conc. KMnO_4} R_2C=O + R'_2C=O$
  - Toluene $\xrightarrow{hot, conc. KMnO_4} Benzoic \ Acid$
- Oxidation of Alcohols:
  - $RCH_2OH \xrightarrow{KMnO_4} RCOOH$ (Primary alcohol to carboxylic acid)
  - $R_2CHOH \xrightarrow{KMnO_4} R_2C=O$ (Secondary alcohol to ketone)
Potassium Dichromate ($K_2Cr_2O_7/H^+$)
- Oxidation of Alcohols: Milder than $KMnO_4$.
  - $RCH_2OH \xrightarrow{K_2Cr_2O_7/H^+} RCOOH$ (Primary alcohol to carboxylic acid)
  - $R_2CHOH \xrightarrow{K_2Cr_2O_7/H^+} R_2C=O$ (Secondary alcohol to ketone)
Chromium Trioxide ($CrO_3$)
- Jones Reagent ($CrO_3/H_2SO_4/Acetone$): Oxidizes primary alcohols to carboxylic acids, secondary alcohols to ketones.
  - $RCH_2OH \xrightarrow{Jones \ Reagent} RCOOH$
  - $R_2CHOH \xrightarrow{Jones \ Reagent} R_2C=O$
- PCC (Pyridinium Chlorochromate) ($CrO_3 \cdot pyridine \cdot HCl$): Selective oxidation of primary alcohols to aldehydes.
  - $RCH_2OH \xrightarrow{PCC} RCHO$
  - $R_2CHOH \xrightarrow{PCC} R_2C=O$ (Secondary alcohol to ketone)
Ozone ($O_3$) - Ozonolysis
- Reductive Ozonolysis ($O_3, Zn/H_2O$ or $DMS$): Cleaves C=C bonds, forms aldehydes/ketones.
  - $RCH=CHR' \xrightarrow{O_3, Zn/H_2O} RCHO + R'CHO$
  - $R_2C=CHR' \xrightarrow{O_3, Zn/H_2O} R_2C=O + R'CHO$
  - $R_2C=CR'_2 \xrightarrow{O_3, Zn/H_2O} R_2C=O + R'_2C=O$
- Oxidative Ozonolysis ($O_3, H_2O_2$): Cleaves C=C bonds, forms carboxylic acids/ketones.
  - $RCH=CHR' \xrightarrow{O_3, H_2O_2} RCOOH + R'COOH$
  - $R_2C=CHR' \xrightarrow{O_3, H_2O_2} R_2C=O + R'COOH$

6. Halogenating Agents

Chlorine ($Cl_2$), Bromine ($Br_2$), Iodine ($I_2$)