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Posts posted by adianadiadi

  1. We know that Grignard reagent is strongly basic. It is stronger than NaOH.  

    We also know that sodium hydroxide is just enough to abstract a proton from active methyl group of acetaldehyde to carry out aldol reaction.

    Now my point is, if we use Grignard reagent, acetaldehyde should undergo aldol reaction instead of Grignard reaction.

    Any comments?

  2. It is possible to extract caffeine from tea powder using carbon tetrachloride. In fact tea powder has more caffeine than coffee beans. As far as I remember, the extraction goes smoothly. Final crystallization with charcoal will give the pure crystals.


    I want to extract some caffeine from coffee. Is it plausible, and if so, how is it done?


    Thanks in advance!



    But look at the carbon I marked red. It is the spiro carbon between two rings and tetrahedral. If the carbon closer to us would migrate, this tetrahedral spiro carbon would become a planar spiro carbon. Now, spiro carbons are never planar - the strain is simply too high (the electon repulsion betwee four coplanar bonds at one atom is too high).



    Sorry to interfere, after a long time, however, I do not see any bond breaking between red and green labelled carbons so that it will make spiro carbon planar. Could you please clarify this? Please try to mark the bonds instead of atoms.


    Thank you.

  4. You can learn chemistry just by asking yourself some basic questions. Is it so you by heart other subjects and it fails when it comes to chemistry? Do you ever try to understand this subject?


    Try at basic levels. Listen to your lecturer carefully. Revise by practicing the subject.



  5. "The positive entropy change is thermodynamically not favored" is not correct.

    According to second law of thermodynamics, all the spontaneous processes involve increase in entropy of universe.

  6. They are not taken as constants. But for pure solids the activity is taken as one. For liquids and gases, it is not one. The activity of solids is one because the active surface of solid which can take part in the reaction is almost negligible when compared to the liquid and gases. But what about for finely divided solids? Is the active surface area still negligible when compared to that of liquids and solids?

  7. The number of valence electrons in boron is 3. Among them, one electrons is contributed

    for B-H bond at the vertex. The remaining 2 electrons are invoved in skeletal bonds formation

    and are termed as skeletal electrons (SE’s). That is why contribution of each B-H to skeletal

    electrons is 2.

    Likewise, carbon contributes 3 electrons to skeleton.

    * a closo-deltahedral cluster cage with ‘n’ vertices requires (n+1) skeletal electron pairs

    (SEP’s) which occupy (n+1) cluster bonding MOs ; It also implies, the skeletal electrons

    (SE’s) must be equal to 2n+2. (i.e. n vertices require 2n+2 electrons in closo cluster)

    * Likewise, a nido-deltahedral cluster cage with ‘n’ vertices requires (n+2) pairs of electrons

    and so on.


    n+1 condition is satisfied only with closo anions and hence more stable.


    Note: Here the value of ‘n’ represents the actual number of vertices in the cluster (or the

    number of boron as well as carbon atoms). According to some textbooks, ‘n’ represents the

    number of vertices in the parent closo cluster.


    You will get more from boranes topic at AdiChemAdi

  8. I would like to introduce you a new site with chemistry content especially with named organic reactions section. It is an educational site with good chemistry articles base.


    You may go through the named organic reactions at following link:



    Some named reactions covered are:


    Michael addition


    Bamford-Stevens reaction


    Cannizzaro reaction


    Favorskii rearrangement


    Phillips condensation reaction for pharmacy students



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