Organic Chemistry

What is the role of atomic size in London Dispersion? Explain with an example.

London dispersion forces are the weak intermolecular forces that occur when the molecules are in close proximity to each other. The strength of these forces is determined by the atomic size of the element.

In smaller atoms, the atomic radius is smaller, which means that the positively charged nucleus holds the outermost valence electrons more firmly, leaving less room for their dispersion or polarization.

Carbocation

A carbocation is a positively charged, trivalent carbon ion that acts as a reactive intermediate in many organic reactions.

With three bonds and only six electrons, carbocations have an incomplete octet and, therefore, electron deficient. It functions as an electron acceptor and an electrophile forming new Carbon-Carbon (C-C) bonds.

Drawbacks of Friedel Craft Acylation Reaction

1) Alkylation

Branched alkyl chlorides (2⁰ or 3^o) cannot be used as a reagent in FC acylation reaction. The branched alkyl chlorides on forming acylium ion undergo the loss of CO to create a stable alkyl cation. The 2⁰ or 3^o alkyl cation reacts with benzene to form alkyl benzene.

Sawhorse Projection

It is a way of visualizing the carbon atoms of an open-chain organic molecule from an oblique angle and projecting that image on a 2-dimensional paper to appear like a carpenter’s sawhorse.

The two adjacent carbons of interest in a chain are drawn as a slant line, and its two groups form the hind and forelegs, with the third forming the head and the tail to resemble a horse from which the name draws an inspiration.

Coordination Compounds

The compounds in which the central metal atom is linked to ligands (anions or neutral molecules) that donate its pair of electrons to form coordinate covalent bonds with the metal atom.

Example, Ni(CO)₄, {Co(NH₃)₆]Cl₃