Calcium hydride , About 92 , 7789-78-8
Synonym(s):
Calcium dihydride
CAS NO.：7789-78-8
Empirical Formula: CaH2
Molecular Weight: 42.09
MDL number: MFCD00010897
EINECS: 232-189-2
PRODUCT Properties
| Melting point: | 816 °C (lit.) |
| Density | 1.9 |
| storage temp. | Store below +30°C. |
| solubility | reacts with H2O, ethanol |
| form | powder |
| Specific Gravity | 1.9 |
| color | Light gray |
| Water Solubility | Soluble in water and alcohol. Insoluble in benzene. |
| Sensitive | Moisture Sensitive |
| Merck | 14,1672 |
| Stability: | Stable, but reacts violently with water, liberating and igniting hydrogen. Contact with strong oxidizers may cause fire or explosion. Incompatible with strong oxidizing agents, strong acids, halogens, water, alcohols. |
| InChIKey | FAQLAUHZSGTTLN-UHFFFAOYSA-N |
Description and Uses
Calcium hydride is a gray powder (white if pure,
which is rare). It reacts vigorously with water liberating
H2 gas. CaH2 is thus used as a drying agent,
i.e. a desiccant. It is prepared directly from the metal
or by reacting CaCO3 with hydrogen at elevated temperatures. The overall reaction is shown as
follows:
CaCO3＋heat＋H2→CaH2＋H2O＋CO2
CaH2 is a saline hydride, meaning that its structure is
salt-like. The alkali metals and the alkaline earth metals
all form saline hydrides. These species are insoluble in
all solvents with which they do not react because they
have extended structures. CaH2 crystallizes in the
PbCl2 structural pattern.
The reaction of CaH2 with water can be represented
as follows:
CaH2＋2H2O0Ca(OH)2＋2H2
The two hydrolysis products, H2, a gas, and Ca(OH)2,
an aqueous mixture of solid plus liquid (i.e. a slurry), are readily separated from the solvent by distillation, filtration, or decantation.
Calcium hydride is used as an efficient drying agent for aprotic base-stable solvents like ethers and tertiary amines. It is a useful dehydrating agent in a synthesis of aldehyde enamines in high yield and purity.
Safety
| Symbol(GHS) |   GHS02,GHS07 |
| Signal word | Danger |
| Hazard statements | H260-H315-H319 |
| Precautionary statements | P223-P231+P232-P264-P280-P302+P352-P305+P351+P338 |
| Hazard Codes | F |
| Risk Statements | 15 |
| Safety Statements | 24/25-43-7/8-43A |
| RIDADR | UN 1404 4.3/PG 1 |
| WGK Germany | 1 |
| TSCA | Yes |
| HazardClass | 4.3 |
| PackingGroup | I |
| HS Code | 28500090 |
