Potassium hydride is an inorganic alkali metal hydride of potassium and hydrogen represented by the chemical formula KH ^[1]. Since it is an extremely reactive compound, it is commercially available as a suspension of small particles in paraffin wax or mineral oil for easier dispensing ^[2].

Potassium Hydride Identification
CAS Number	7393-26-7 [1]
PubChem CID	82127 [1]
ChemSpider ID	74121 [3]
EC Number	231-704-8 [1, 4]
RTECS Number	N/A [4]
InChI Key	OCFVSFVLVRNXFJ-UHFFFAOYSA-N [1]

How is Potassium Hydride Prepared

The synthesis of potassium hydride involves a direct combination of potassium and hydrogen represented by the following equation:

2K + H₂ → 2KH

The method of preparation was invented by Sir Humphry Davy after he discovered potassium in 1807 through electrolysis of caustic potash (now called potassium hydroxide) ^[5].

Reaction with Water

Potassium hydride undergoes a violent reaction with water, producing potassium hydroxide and hydrogen that can burn ^[6]. It is represented by the following reaction:

KH + H₂O → KOH + H₂

Properties and Characteristics of Potassium Hydride

General Properties
Molar Mass/Molecular Weight	40.106 g/mol [1, 4]
Physical Properties
Color and Appearance	White or colorless crystalline solid, gray (commercial sample) [1, 4]
Melting Point	~ 400 °C, 752 °F (decomposes) [3, 7]
Boiling Point	N/A [4]
Density	1.47 g cm-3 [4]
Charge	0 (K+ and H–) [1, 3]
State of matter at room temperature	Solid [1, 4]
Solubility	Insoluble in diethyl ether, benzene, and CS2 [8]
Solubility in Water	Decomposes in hot and cold water [8]
Heat Capacity (C)	37.91 J/(mol.K)
Acid Dissociation Constant at Logarithmic Scale (pKa)	35 [9]
Atomic Properties
Crystal Structure	Cubic

Uses

• As a donor of hydride and base to Lewis acids like borates and boranes ^[8]
• For deprotonating carbonyl compounds and amines to form enolates and amides respectively ^[8]
• In cyclization-condensation, rearrangement, elimination, and reducing reactions ^[8]

Is it Safe

KH is a pyrophoric compound and thus ignites in contact with air. It also produces flammable gases upon reacting with water ^[1]. Exposure to potassium hydride may cause eye damage and skin corrosion or burns ^[1].

References
1. Potassium Hydride – Pubchem.ncbi.nlm.nih.gov
2. Potassium Hydride in Paraffin: A Useful Base for Organic Synthesis – Pubs.acs.org
3. Potassium Hydride – Chemspider.com
4. Potassium Hydride – Americanelements.com
5. Science and Celebrity: Humphry Davy’s Rising Star – Sciencehistory.org
6. Potassium Hydride And Sodium Hydride – Web.stanford.edu
7. Potassium Hydride – Webelements.com
8. Potassium Hydride – Onlinelibrary.wiley.com
9. PK_a Values of Common Bases – Uwindsor.ca