Boron Tribromide(BBr3) Properties(25 Facts You Should Know)

Boron tribromide(BBr3) appears as an odourless, liquid that is fuming. Let us discuss its important facts in detail.

Boron tribromide is also known as BBr3, a chemical that contains both boron and bromine. Commercial samples often have minor bromine contamination and are amber to reddish-brown. Boron tribromide is a highly water-soluble crystalline source of the element. Group OH and water break BBr3.

Let us discuss the properties of boron tribromide(BBr3), including its IUPAC name, molecular mass, density, radius, and whether it is acidic or basic.

Boron tribromide IUPAC name

The IUPAC (International Union of Pure and Applied Chemistry) name for BBr3 is tribromoborane. The suffix “ide” is due to bromine being present as an anionic component.

Boron tribromide chemical formula

Boron tribromide’s chemical formula is BBr3. In this, three bromine atoms are joined to the centre boron atom by a single bond. Tribromoborane, or boron bromide, is another name for the substance

Boron tribromide CAS number

Boron tribromide’s(BBr3) CAS registration number is 10294-33-4(a valid numeric identification that can contain up to 10 digits).

Boron tribromide ChemSpider ID

Boron tribromide’s(BBr3) ChemSpider ID is 23479 which is unique for each molecule.

Boron tribromide chemical classification

Boron tribromide(BBr3) is classified into the following categories:

  • Boron tribromide(BBr3) is a Lewis acid that is strong.
  • Boron tribromide(BBr3) behaves as a demethylating or dealkylating agent.
  • An inorganic substance is called boron tribromide(BBr3).
  • Boron tribromide(BBr3) is an organic reagent to form diborane.
  • Boron tribromide(BBr3) is a highly water-soluble crystalline boron source.

Boron tribromide molar mass

  • The molar mass of boron tribromide(BBr3) is 250.52 g·mol−1. It is the total atomic mass of three Br atoms plus one B atom. 
  • B has an atomic mass of 10.8 g·mol−1 and each Br has an atomic mass of 79.884 g·mol−1
  • Because there are three Br atoms present, the total molar mass of the compound BBr3 is 10.8 + (79.884*3) = 250.52 g·mol−1.

Boron tribromide color

The liquid form of boron tribromide(BBr3) is colourless to amber-yellow.

Boron tribromide viscosity

The viscosity of boron tribromide(BBr3) is 7.31 x 10−4 Pa s  at 20 °C or 0.731 cP at 75 °F.

Boron tribromide molar density

Boron tribromide(BBr3) has a molar density/volume of 2.643 g/cm3. The volume of each element is 22.4L, and since there are three elements present, the molar mass of liquid BBr3 is 250.52 g·mol−1, making its molar density 2.643 g/cm3. 

Boron tribromide melting point

The melting point of boron tribromide(BBr3) is -46.3 °C (51.3 °F; 226.8 K). Since BBr3 has a weak lattice structure and a lower melting point than 100 °C, it can dissolve into a liquid state below this temperature.

Boron tribromide boiling point

The boiling point of boron tribromide(BBr3) is 91.3 °C (196.3 °F; 364.4 K).

Boron tribromide state at room temperature

Boron tribromide(BBr3) is a fuming, colourless liquid that is present at room temperature. For every mole of boron tribromide that is present, three moles of hydrogen bromide should be produced throughout the breakdown process.

Boron tribromide ionic/covalent bond

The molecule Boron tribromide(BBr3) is a covalent compound because the B and Br atoms are joined by covalent bonds and have no formal charge. Its planar structure is created by the covalent bonds between the three bromine atoms and a centre B atom. Atomic unity is maintained through covalent bonding.

Boron tribromide ionic/covalent radius

The Covalent radius for boron tribromide(BBr3) cannot be determined because it can be calculated only for any single atom. 

Boron tribromide electron configurations

Electronic configuration refers to how electrons are arranged within an element’s atomic orbitals. Let us look at the electronic configuration of boron tribromide(BBr3).

  • The electronic configurations of the boron atoms in boron tribromide(BBr3) are [He]1s22s22p1 & [He]1s22s12p2 in the ground state and excited state, respectively.
  • The electronic configuration of the bromine atom in boron tribromide(BBr3) is [Ar]3d104s24p5.

Boron tribromide oxidation state

The central atom, boron, is in a +3 oxidation state in boron tribromide(BBr3). Each of the 3 bromine atoms is in a -1 oxidation state in boron tribromide. Three Br atoms in a -1 oxidation state result in the molecule being chargeless, while three B atoms in a +3 oxidation state satisfy the charge.

Boron tribromide acidity/alkaline

  • Boron tribromide(BBr3) has an acidic nature and retains the boron’s electron deficit property. 
  • BBr3 is a Lewis Acid because it accepts electron pairs.
  • BBr3 has an unfavourable overlap between the occupied 4p orbital and the unoccupied 2p orbital. 
  • Due to BBr3 considerable energy differences, the back bonding is less successful in the p orbitals of boron and 4p orbitals of bromine.

Is boron tribromide odourless?

Boron tribromide(BBr3) has a sharp, unpleasant smell. 

Is boron tribromide paramagnetic?

Atoms and molecules with unpaired electrons in their valency shells are said to have a paramagnetism. Let us talk about the magnetism of Boron tribromide(BBr3).

Boron tribromide(BBr3) is neither paramagnetic nor diamagnetic because all three of the valence electrons for B are utilised in the bond formation with the three Br atoms. Therefore, we are unable to predict its magnetic behaviour in the absence of electrons.

Boron tribromide hydrates

  • The boron tribromide(BBr3) molecule does not have the hydrated portion, but when the dibromoborane has been hydrolyzed, it can yield a hydroxyl group, boric acid, and hydrogen bromide.
  • The compound boron tribromide can be used to make boric acid. This is an instance of hydrolysis.
  • The following equation describes how boron tribromide is converted into boric acid: 

B(OH)3 + 3HBr → BBr3 + 3H2O

ROR + BBr3 + 3H2O → ROH + B(OH)3 + 2HBr

Boron tribromide crystal structure

The boron tribromide (BBr3) is a naturally occurring liquid, and while its trigonal planar structure may be predicted using VSPER theory, it does not exist in crystal form. Below is an image showing the structure:

boron tribromide properties
BBr3 trigonal planar structure

Boron tribromide polarity and conductivity

The boron tribromide (BBr3) is non-conductive and non-polar due to the following factors:

  • In BBr3, the three Br atoms that surround the core Boron atom are symmetrical, so the dipole moment of B-Br is cancelled out, making the molecule non-polar.
  • The B-Br bonds are positioned 120° apart from one another in a plane.
  • BBr3 can’t conduct electricity when it is solid or molten because of the covalent bonds between the three Br atoms surrounding the core B atom.

Boron tribromide reaction with acid

The boron tribromide(BBr3) reaction of acid is extremely minimal because BBr3 is a powerful Lewis acid molecule by itself, but it can react with an organic protic solvent and water molecule. 

Boron tribromide reaction with base

The boron tribromide(BBr3), bases often serve as a Lewis base. Being a Lewis acid, it can interact with Lewis bases, accepting their lone pairs or electron densities, and creating an adduct or complex in the process. Consider this equation:

BBr3 + NaOH → (BBr3OH) + Na+

Boron tribromide reaction with oxide

In the presence of boron tribromide(BBr3), oxides form an adduct. A good example of metal oxides is: 

BBr3 + MgO →(BBr3)(MgO)+

Boron tribromide reaction with metal

Metals are species-rich in electrons. They help the borane tribromide(BBr3)form an ionic species by providing electrons. For example:

BBr3 + Li → (BBr3)(Li)+

Conclusion

Borane tribromide(BBr3) is created when boron carbide and bromine combine at temperatures above 300°C. It also functions as a Lewis acid catalyst in Friedel-Crafts chemistry and the polymerization of olefins. Boron tribromide(BBr3) is a boron source used in pre-deposition processes for doping in the production of semiconductors.

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