Cocl2 Lewis Structure,Characteristics:13 Facts You Should Know


cocl2 lewis structure, and some important facts are going to be discussed in this article.

Phosgene,COCl2 is a compound with a carbonyl carbon attached with two chorine atoms. It is a toxic compound which is used for the synthesis of certain products.

Facts about Phosgene, COCl2

COCl2 or phosgene is an organic compound which consists chlorine , oxygen and carbon atoms. Chemically it is carbonyl dichloride. Other names are known like carbon oxy chloride, chloro formyl chloride etc. It is prepared by the reaction of pure carbon monoxide with chlorine gas by using activated carbon as catalyst. It’s an exothermic reaction.

Phosgene is a toxic compound with no colour. It is a gaseous substance with suffocating odour. It’s odour seems like the smell of freshly cut hay or grass. It’s molar mass is 98.92g/mol. It is found to be non- inflammable. Sometimes the decomposition of certain chlorinated compounds release phosgene into the atmosphere.

It is one of the main building block for the synthesis of polyurethanes and polycarbonate plastics. Phosgene is also used for the production of MDI, methylene diphenyl diisocyanate and TDI toluene diisocyanate. Being a corrosive gas it’s inhalation cause severe respiratory problems.

Lewis Structure of COCl2

The Lewis structure of phosgene can be drawn through the subsequent steps. Actually Lewis structure is the simple representation of organisation of electrons around atoms.

  • In the first step we need to determine the total valence electrons in the compound. The valence electrons present in carbon, oxygen and chlorine is 4,6,7. So the total is 4+6+7×2 = 24 electrons.
  • In the second step write carbon as the central atom surrounded with two chlorine and oxygen. Make single bonds between them. After making this single bonds the electrons remaining is18. It is filled to the other atoms in accordance with octet rule.
Stable Lewis structure of COCl2
  • So the oxygen atom will again forms bond with carbon by sharing it’s electrons. The formal charge is now zero for the atoms present here. So this Lewis structure with zero formal charge will be very stable structure and it is considered.
Stable Lewis structure of COCl2

Resonance in COCl2

There is three resonance structures are seen for phosgene. It is due to the involvement of lone pairs present in chlorine atoms. When they get into resonance positive and negative charge were obtained by chlorine and oxygen respectively. The resonance structure of phosgene is shown below.

Resonance in COCl2

Octet Rule in COCl2

We all know that atoms should form bond in such a way that their valence shell is filled with eight electrons after bond creation. This is called octet rule. Here all the atoms obey octet rule. The three atoms called chlorine, carbon and oxygen has eight electrons in their valence shell after bond formation. So they obeys octet rule.

Octet in COCl2

Formal charge in COCl2

The charge gave to an atom in a molecule by considering that all the electrons involved in the chemical bonds are equally shared by the atoms is the definition for formal charge. Formal charge of an atom is calculated by considering its most firm Lewis structure. The equation for formal charge calculation is

Formal charge = Valence electrons – Non bonding electrons – No of bonds

                             Made

Formal charge in carbon = 4-0-4 = 0

Formal charge in chlorine = 7-6-1 = 0

Formal charge in oxygen = 6-4-2 = 0

Valence electrons in COCl2

The total number of valence electrons in phosgene is 24.

Lone Pairs in COCl2

Phosgene has lone pairs associated with it. Carbon is the central atom and all its four valence electrons are involve in bonding . So there is zero lone pair in carbon. But the chlorine and oxygen has lone pairs in it. Oxygen has two and each chlorine has three. So in total there are eight lone pairs found in phosgene.

Shape and Bond Angle in COCl2

The shape of the molecule is triagonal planar. The shape of the any molecule can be found through VSEPR theory. This theory is used to predict the geometry of any molecule. It is based on the number of bond pairs in the molecule and how it arrange itself to undergo minimum repelsion with other atoms.

Carbonyl dichloride is a AX3 type molecule with no lone pairs in central carbon atoms. So it’s shape is triagonal planar. All the atoms are in same plane. The bond length of C-Cl and C-O bonds are different. C-Cl has 174pm and C-O has 118pm. The bond angle between Cl –C-Cl bond is almost 111.80.

Shape and Bond Angle of COCl2

Hybridisation of COCl2

The hybridisation in phosgene is sp2 hybridization. Let’s see how it undergoes sp2 hybridization. The ground state electronic configuration of carbon is 1s2 2s2 2p2 . When one of the electron in 2s orbital got excited then it is 1s2 2s1 2p3. Now one 2s and two 2p orbitals overlaps together to form sp2 hybridized orbitals.

Then this orbitals with one electron makes bond with two chlorine and one oxygen. One of the unhybridised 2pz orbital in carbon then overlapps sidewise with oxygen atom to make a pi bond.

Hybridisation can be found through knowing its steric number .

Steric number = No of atoms attached to the central atom + No of lone pairs present in central atom.

Here, the Steric number = 3+0 = 3

Hybridisation = sp2

Hybridisation in COCl2

Solubility of COCl2

Phosgene is found to insoluble in water. But it is highly soluble in benzene, toluene, chloroform and liquid hydrocarbons. Mostly phosgene undergoes decomposition when it is tried to dissolve in ethanol and acids.

Is COCl2 Ionic or not ?

Phosgene is a covalent compound in which each bond is made through the equal sharing of electrons between the atoms.

Is COCl2  is Polar or not ?

Phosgene is a polar molecule. Polarity of a molecule can be understood by considering two things. One is the electronegativity difference between the atoms. Second, is it symmetrical or not. If the electronegativity is different but the molecule is symmetrical then it’s polarity got cancelled and remain as a non polar molecule.

Here the electronegativity difference of C- Cl bond is 0.61 and C-O bond is 0.89. It is not in a symmetrical arrangement. So the polarity won’t get cancelled. So it’s a polar molecule.

Is COCl2 Acidic or not ?

When phosgene reacts with water it forms HCl.

Is COCl2 Tetrahedral or linear ?

Phosgene is neither tetrahedral nor linear. It’s a triagonal planar molecule with all atoms in a single plane.

Is COCl2 Symmetric or not ?

No, phosgene is not a symmetric molecule. It’s an unsymmetrical molecule.

Conclusion

Phosgene is an organic compound with formula COCl2. This article concludes that it has triagonal planar shape with 111.80 bond angle. Its hybridisation is sp2. It contains 24 valence electrons with lone pairs in it. Its formal charge is zero which is calculated from its most stable Lewis structure.

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