The impure amorphous product a brownish black powder, was the only form of boron known for more than a century. Many of its compounds are electron deficient and has unusual type of covalent bonding which is due to its small size, high ionization energy and similarity in electronegativity with carbon and hydrogen. Pure crystalline boron may be prepared by reduction of its bromide or chloride with hydrogen on an electrically heated tantalum filament.
Boron reacts with halogen elements to form highly reactive trihalides. Boron trihalides and trimethylamine reacted to form complex.
BCl3 + N(CH3)3 ———> (CH3)3N.BCl3
Formation Of Hydrides:
With hydrogen boron forms a series of compounds called boranes. The simplest borane is Diborane ( B2H6 ). Boron trifluoride react with sodium hydride around 450K ( Heat ) to form diborane.
2BF3 + 6NaH ———> B2H6 + 6NaF
Formation Of Boron Oxides:
Boron reacts with oxygen around 900K ( heat ) to form its oxide.
4B + 3O2 ———> 2B2O3
Reaction With Acid And Alkali:
Boron is most easily converted into boric acid by treatment with acids like sulphuric acid and nitric acid.
2B + 3H2SO4 ———> 2H3BO3 + 3SO2
B + 3HNO3 ———> H3BO3 + 3NO2
Boron reacts with sodium hydroxide to form sodium borate.
2B + 6NaOH ———> 2Na3BO3 + 3H2