| Revision as of 13:42, 6 August 2011 editLuckas-bot (talk | contribs)929,662 editsm r2.7.1) (robot Adding: vi:Natri nhôm hiđrua← Previous edit |
Latest revision as of 10:28, 18 September 2024 edit undoLavateraguy (talk | contribs)Autopatrolled, Extended confirmed users11,600 editsm there was more |
| (56 intermediate revisions by 34 users not shown) |
| Line 1: |
Line 1: |
|
{{chembox |
|
{{chembox |
|
|
| Verifiedfields = changed |
| ⚫ |
| verifiedrevid = 399656161 |
|
|
|
| Watchedfields = changed |
|
| ImageFile = |
|
|
⚫ |
| verifiedrevid = 443346228 |
|
| ImageSize = |
|
|
|
| ImageFile1 = CaWO4.tif |
|
|
| ImageSize1 = |
|
|
| ImageFile2 = File:NaAlH4.png |
|
|
| ImageSize2 = |
|
| IUPACName = Sodium aluminium hydride |
|
| IUPACName = Sodium aluminium hydride |
|
| OtherNames =Sodium tetrahydroaluminate |
|
| OtherNames =Sodium tetrahydroaluminate |
|
| Section1 = {{Chembox Identifiers |
|
|Section1={{Chembox Identifiers |
|
|
| CASNo_Ref = {{cascite|correct|??}} |
|
| CASNo = 13770-96-2 |
|
|
| Einecs = 237-400-1 |
|
| CASNo = 13770-96-2 |
|
| HSDB = 690 |
|
| EINECS = 237-400-1 |
|
| PubChem = |
|
| PubChem = 26266 |
|
|
| InChI = 1S/Al.Na.4H/q-1;+1;;;; |
|
| SMILES = |
|
| SMILES = . |
|
|
| UNNumber = 2835 |
|
}} |
|
}} |
|
| Section2 = {{Chembox Properties |
|
|Section2={{Chembox Properties |
|
| Na = 1 | Al = 1 | H = 4 |
|
| Na=1 | Al=1 | H=4 |
|
| Appearance = White crystalline solid |
|
| Appearance = White or gray crystalline solid |
|
| Density = 0.905 g/mL at 25 °C |
|
| Density = 1.24 g/cm<sup>3</sup> |
|
| MeltingPt = |
|
| MeltingPtC = 178 |
|
| BoilingPt = |
|
| BoilingPt = |
|
| Solubility = Soluble in THF |
|
| Solubility = |
|
|
| SolubleOther = soluble in ] (16 g/100 mL at room temperature) |
|
}} |
|
}} |
|
| Section3 = {{Chembox Hazards |
|
|Section3={{Chembox Hazards |
|
|
| ExternalSDS = |
|
| ExternalMSDS = |
|
|
| FlashPt = -7 °F (-22 °C) |
|
| FlashPtF = -7 |
|
|
| AutoignitionPtC = 185 |
|
|
|
|
|
| GHSPictograms = {{GHS02}}{{GHS05}}{{GHS07}} |
|
|
|
|
| Autoignition = |
|
| NFPA-H = 3 |
|
|
| NFPA-F = 2 |
|
|
| NFPA-I = 0 |
|
|
| NFPA-S = W |
|
|
| LD50 = 740 mg/kg (oral, mouse) |
|
}} |
|
}} |
|
}} |
|
}} |
|
|
|
|
|
|
'''Sodium aluminium hydride''' or '''sodium alanate''' is an ] with the ] NaAlH<sub>4</sub>. It is a white ] solid that dissolves in ], but not in ] or hydrocarbons. It has been evaluated as an agent for the reversible storage of hydrogen and it is used as a ] for the ] of ]s. Similar to ], it is a ] consisting of separated ] ] and tetrahedral AlH{{su|b=4|p=−}} ]s.<ref name="ACB">J. W. Lauher, D. Dougherty P. J. Herley "Sodium tetrahydroaluminate" Acta Crystallogr. 1979, volume B35, pp.1454-1456. {{doi|10.1107/S0567740879006701}}</ref> |
|
'''Sodium aluminium hydride''' (NaAlH<sub>4</sub>) or '''sodium alanate''' is a ] used as a ]. It is similar to ]. |
|
|
It is used for ] in ]s,<ref>{{cite journal | doi = 10.1016/S0925-8388(99)00666-0 | title = Sodium alanates for reversible hydrogen storage | year = 2000 | author = A. Zaluska, L. Zaluski and J. O. Ström-Olsen | journal = ] | volume = 298 | pages = 125 }}</ref> the sodium tetrahydroaluminate can absorb up to 7.4 wt of hydrogen, with hydrogen released when heated at {{convert|200|°C|°F}}. ] can be slow and take up to 15 minutes to fill a tank. |
|
|
|
|
|
|
|
==Structure, preparation, and reactions== |
|
Sodium aluminium hydride is a strong reducing agent. Similar in reactivity to lithium aluminum hydride. May react violently with oxidizing agents.Its action is simailar to DIBAL in organic reactions. |
|
|
|
Sodium tetrahydroaluminate adopts the structure of (is isostructural with) ]. As such, the tetrahedral AlH{{su|b=4|p=−}} centers are linked with eight-coordinate Na+ cations.<ref name="ACB" /> |
|
:RCOOR' + H<sub>2</sub> + NaAlH<sub>4</sub>(reducing agent) → RCOOH + R'OH |
|
|
|
The compound is prepared from the elements under high pressures of H<sub>2</sub> at 200 °C using ] catalyst:<ref>Peter Rittmeyer, Ulrich Wietelmann "Hydrides" in Ullmann's Encyclopedia of Industrial Chemistry, 2002, Wiley-VCH, Weinheim. {{doi|10.1002/14356007.a13_199}}</ref> |
|
|
|
|
|
:Na + Al + 2 H<sub>2</sub> → NaAlH<sub>4</sub> |
|
LAH is the more powerful reducing agent than sodium borohydride due to the weaker Al-H bond compared to the B-H bond. The reactivity of sodium borohydride can be modified by addition of iodine or methanol in BH3-THF to reduce esters into the corresponding alcohols like the reaction of benzyl benzoate to benzyl alcohol |
|
|
|
|
|
|
|
As a suspension in diethyl ether, it reacts with ] to give the popular reagent ]: |
|
] can be used to efficiently produce sodium aluminium ] (NaAlH<sub>4</sub>) by ] in ]: |
|
|
:LiAlH<sub>4</sub> + NaH → NaAlH<sub>4</sub> + LiH |
|
:LiCl + NaAlH<sub>4</sub> → LiAlH<sub>4</sub> + NaCl |
|
|
|
|
|
|
The compound reacts rapidly, even violently, with ] reagents, such as water, as described in this idealized equation: |
|
By adding ] the kinetics of hydrogen release and recharge are improved.<ref></ref> |
|
|
|
:4 H<sub>2</sub>O + NaAlH<sub>4</sub> → "NaAl(OH)<sub>4</sub>" + 4 H<sub>2</sub> |
|
|
|
|
|
|
==Applications== |
| ⚫ |
Sodium aluminium hydride is highly flammable. Does not react in dry air at room temperature. Very sensitive to moisture. Ignites or explodes on contact with water or moist air. |
|
|
|
|
|
|
===Hydrogen storage=== |
|
|
Sodium alanate<ref></ref> has been explored for ] in ]s.<ref>{{ cite journal |author1=Zaluska, A. |author2=Zaluski, L. |author3=Ström-Olsen, J. O. | title = Sodium Alanates for Reversible Hydrogen Storage | journal = Journal of Alloys and Compounds | year = 2000 | volume = 298 | issue = 1–2 | pages = 125–134 | doi = 10.1016/S0925-8388(99)00666-0 }}</ref> The relevant reactions are: |
|
|
: 3 NaAlH<sub>4</sub> → Na<sub>3</sub>AlH<sub>6</sub>+ 2 Al + 3 H<sub>2</sub> |
|
|
: Na<sub>3</sub>AlH<sub>6</sub> → 3 NaH + Al + 3/2 H<sub>2</sub> |
|
|
|
|
|
Sodium tetrahydroaluminate can release up to 7.4 wt % of hydrogen when heated at {{convert|200|°C|°F}}. ] can be slow, with several minutes being required to fill a tank. Both release and uptake are catalysed by ].<ref>{{ cite web | url = http://phys.org/news123307288.html | title = Researchers Solve Decade-Old Mystery of Hydrogen Storage Material | publisher = Phys.Org | date = 2008-02-27 }}</ref> |
|
|
|
|
|
===Reagent in organic chemistry=== |
|
|
Sodium aluminium hydride is a strong ], very similar in reactivity to ] (LAH) and, to some extent, ] (DIBAL) in organic reactions.<ref>Melinda Gugelchuk "Sodium Aluminum Hydride" Encyclopedia of Reagents for Organic Synthesis, 2001, John Wiley. {{doi|10.1002/047084289X.rs039}}</ref> It is much more powerful reducing agent than ] due to the weaker and more ] Al-H bond compared to the B-H bond. Like LAH, it reduces ]s to ]s. |
|
|
|
|
|
==Safety== |
|
⚫ |
Sodium aluminium hydride is highly flammable. It does not react in dry air at room temperature but is very sensitive to moisture. It ignites or explodes on contact with water. |
|
|
|
|
|
==See also== |
|
==See also== |
| Line 49: |
Line 73: |
|
== References == |
|
== References == |
|
{{Reflist}} |
|
{{Reflist}} |
|
|
{{sodium compounds}} |
|
|
|
|
|
{{aluminium compounds}} |
|
{{Inorganic-compound-stub}} |
|
|
|
|
|
|
] |
|
] |
|
] |
|
] |
|
] |
|
] |
|
] |
|
] |
|
|
] |
|
|
|
|
] |
|
|
] |
|
|
] |
|
|
] |
|