December 30, 2012

GENERAL METHODS OF PREPARATION OF CARBONYL COMPOUNDS

GENERAL PROPERTIES OF CARBONYL COMPOUNDS


Sl.
No.
ALDEHYDES
( HCHO, CH3CHO,
C6H5CHO )
KETONES
( CH3COCH3,
C6H5COCH3, C6H5COC6 H5 )
1
Strong and even mild oxidising agents oxidise them to mono carboxylic acids having the same number of carbon atoms.
Strong oxidising agents only oxidise them to mono carboxylic acids having lesser number of carbon atoms.
2
Restores the original colour of the Schiff’s reagent.
Does not restore the colour of Schiff‘s reagent.
3
Reduces Tollen’s reagent to metallic silver (i.e Gives Silver Mirror)
Does not reduce.
4
Aliphatic aldehydes alone reduce Fehling’s solution to red Cu2O.
Do not reduce.
5
Na / Hg + H2O or LiAlH4 or NaBH4 or H2 / Pt reduce them to 1o alcohols.
Na / Hg + H2O or LiAlH4 or NaBH4 or H2 / Pt reduce them to 2o alcohols.
6
Aldehydes not having α –H atom alone with base undergo Cannizzaro reaction.
Do not undergo
7
Aldehydes having α –H atom alone with base undergo Aldol condensation.
Ketones having α –H atoms alone with base undergo Aldol type condensation.
8
With Grignard reagent HCHO gives 1o alcohol and other aldehydes give 2o alcohols.
Gives 3o alcohols.
9
Forms addition products with NaHSO3
Acetone forms addition products with NaHSO3 while others does not form.
10
HCHO and C6H5CHO forms condensation products with NH3 while
CH3CHO forms addition products with NH3
Acetone alone forms condensation products with NH3
11
Aromatic aldehydes alone form Schiff 's base with 1o amines
Do not form Schiff ’s base (or Anils)

12
The aldehydes having CH3CO- group (CH3CHO) undergo Haloform reaction
The Ketones having CH3CO - group (CH3COCH3 and C6 H5COCH3 ) undergo Haloform reaction.
13
Aromatic Aldehydes alone undergo electrophilic substitution reaction at meta-position
Aromatic Ketones alone undergo electrophilic substitution reaction at meta-position
14
Aromatic aldehydes alone undergo
Benzoin condensation,
Perkin’s reaction,
Claisen or Claisen-Schimidt reaction, Knoevenagal reation.
Do not undergo
15
Aliphatic aldehydes alone undergo polymerization
Do not undergo
Aldehydes and Ketones:
1) React with HCN to form cyanohydrin.
2)  Undergo condensation (addition followed by elimination) reaction with ammonia derivatives which contain primary amino group (NH2OH, NH2NH2, NH2NHC6H5, NH2NHCONH2) to form compounds containing carbon-nitrogen double bonds.     
                                         OH
                                           |
> C = O +  H2N - Z     - C -    → > C = N - Z + H2O
                                           |
                                          NH-Z
                                        Unstable
Where, Z = -H, Alkyl (-R), Aryl (Ar), -OH, -NH2, -NH C6H5, -NHCONH2, etc.
3) Clemmenson reduction (or) Wolff-Kishner reduction converts them to hydrocarbons (> C = O group is reduced to – CH2 – group)
GENERAL METHODS OF PREPARATION OF CARBONYL COMPOUNDS

Extraction of the Metals



S. No.
Metal
Extraction of the Metal / Metallurgy
1
Copper,

      Cu
1) Chief ore : Copper pyrites, CuFeS2
2) Concentration : By Froth floatation process
3) Roasting : Volatile impurities S, P, As and Sb are removed as their oxides 
           S + O2 → SO2
           P4 + 5O2 2P2O5
           4As + 3O2 2AsO3
   Copper pyrites are partly converted into Sulphides of Cu & Fe
       2CuFeS2 + O2 Cu2S + 2FeS + SO2 (Major Reaction) 
       2FeS + O2 → 2 FeO + 2SO2  (Minor Reaction)
4) Smelting :
          2FeS + 3O2     2FeO + 2FeO + 2SO2
          FeO + SiO2      FeSiO3 (slag)
          2Cu2S + 3O2   2 Cu2O + 2SO2
          Cu2O + FeS    → Cu2S + FeO
          FeO + SiO2    → FeSiO3 (slag)
5) Bessemerisation :
          2 Cu2S + 3O2    → 2 Cu2O + 2 SO2
          2 Cu2O + Cu2S  → 6 Cu + SO2
          Blister copper contains 98 % Copper
6) Purification : Electrolytic Refining
          Anode (+)    : Impure Cu
          Cathode (–) : Pure Cu
          Electrolyte   : CuSO4 + dil. H2SO4
       On passing current, pure Cu is deposited at the Cathode.
2
Chromium,

     Cr
1) Chief ore : Chromite (or) Chrome ore, FeO.Cr2O3
2) Concentration : By Gravity separation process
3) Conversion of concentrated Chromite ore into Na2CrO4 (Roasting)                                                      900 – 1000oC
     4(FeO.Cr2O3) + 8Na2CO3 + 7O2 (from air) ------------>
                                          8Na2CO3 + 2Fe2O3 + 8CO2
                                          Soluble       Insoluble
4) Conversion of Na2CrO4 into Na2Cr2O7
       2Na2CrO4 + H2SO4 → Na2Cr2O7 + Na2SO4 + H2O
5) Conversion of Na2Cr2O7 into Cr2O3 (Reduction of the dichromate)
       Na2Cr2O7 + 3C →  Na2Cr2O4 + 3CO
       Na2Cr2O4 + H2O → 2NaOH + Cr2O3
6) Reduction of Cr2O3 into Cr : Alumino thermic process   
     Diagram with labels
     Cr2O3 is reduced with Al powder (3:1)
     Ignition mixture : BaO2 + Mg powder
      The mixture is ignited by a piece of Mg ribbon
     Cr2O3 + 2Al → 2Cr + Al2O3 + 468.6 kJ
                                         (slag)
3
Zinc,

   Zn
1) Chief ore : Zinc blende, ZnS
2) Concentration : By Froth Floatation process
3) Roasting : 2ZnS + 3O2 1200 K 2ZnO + 2SO2
4) Reduction : ZnO + C 1673 K Zn + CO
5) Purification : Electrolytic Refining
     Anode (+)    : Impure Zn
     Cathode (–) : Pure Zn
     Electrolyte  : ZnSO4 + dil. H2SO4  
     On passing current pure Zn gets deposited on the Cathode
4
Silver,

     Ag
1) Chief ore : Argentite (or) Silver glance, Ag2S
2) Concentration : By Froth floatation process
3) Treatment of the concentrated ore with NaCN:
Mac Arthur Forrest’s Cyanide process
      Ag2S + 4NaCN 2 Na[Ag(CN)2] + Na2S
4) Precipitation of Silver
     2Na[Ag(CN)2] + Zn → 2Ag + Na2[ Zn(CN)4 ]
5) Purification : Electrolytic Refining
     Anode (+)   : Impure Ag
     Cathode (–) : Pure Ag
      Electrolyte : AgNO3 + 1% HNO3
    On passing electricity pure Ag gets deposited at the Cathode.
5
Gold,

       Au
1) Chief ore : Sulphide (or) Telluride ore.
2) Concentration : By Froth floatation process
3) Roasting : Volatile impurities S, As and Te are removed as their oxides.
4) Treatment of the concentrated ore with KCN:
Mac Arthur Forrest Cyanide process
     4 Au + 8KCN + 2H2O + O2 → 4K[Au(CN)2] + 4KOH
5) Precipitation of Gold :
      2K[Au(CN)2] + Zn → K2[Zn(CN)4] + 2Au
6) Purification : Electrolytic Refining
     Anode (+)    : Impure Au
     Cathode (–) : Pure Au
      Electrolyte : AuCl3 + 10 – 12% HC
    On passing current pure Au gets deposited at the Cathode.

December 29, 2012

USES OF LOGARITHAMIC TABLE

1. The Periodic table giving Atomic Number &

Chemical Symbols for each element

1. Position of the element in the periodic table ( Group No.____ & period No.____ )
2. Atomic number of the element      \
3. Chemical symbol of the element   /Nuclear Chemistry
4. s-Block elements
5. p-Block elements
6. d-Block elements
7. f-Block elements
8. Lanthanides / Lanthanones / 4f-block elements
9. Actinides / Actinones / 5f-block elements
 10. Atomic weight of the elements for the calculation of  M. Wt & F. Wt
 11. E, Z – Nomenclature

2. The Arrangement of electrons in atoms

1. To write the Electron Dot Formula / Electron Structure
2. Molecular orbital theory – Electronic configuration
3. Comparison of IE using Electronic configuration   \
4. Comparison of EA using Electronic configuration /Periodic Properties
5. Calculation of µ (Paramagnetic moment)
6. Colour of the metal / ion / complex
[d0, d10 – Colourless, d1-9 – Coloured]
7. Magnetic property of the metal / ion / complex
[d0, d10 – Diamagnetic, d1-9 – Paramagnetic]
8. Calculation of Effective Nuclear Charge (Z*)

3. Properties of the elements

1. Comparison of IE using values   \
2. Comparison of EA using values   |
3. Comparison of EN using values   |Periodic Properties
4. Comparison of IR using values     |
5. Comparison of CR using values  /
6. To know the oxidation number(s) of  the elements
7. Equivalent weight calculation – Electrochemistry – II
8. Formula Weight & molecular Weight calculation