Strem Chemicals UK is now distributing a very exciting product – potassium graphite KC8.

Strem Chemicals UK is now distributing a very exciting product – potassium graphite KC8.

 An excellent reducing agent of which the electronic properties of potassium intercalated graphite promote a variety of uses in chemical synthesis

 This deep, golden-bronze solid of potassium intercalated graphite KC8  (19-1935)  CAS 12081-88-8 is quite a spectacular material.  Its impressive colour is attributed to its unique structure comprising potassium atoms localized between planar graphite layers (Fig. 1).  In 1965, G.R. Hennig recognized that the colour of the intercalated compound indicates the extent of charge transfer from the potassium atoms to the graphite.1-2 As a result, this brilliantly coloured material exhibits a range of electronic and redox properties for potential applications

 KC8 is a fundamental example and frequently studied material within the unique class of Graphite Intercalation Compounds (GICs) which feature graphite-based host-guest systems.  The host (graphite) interacts with the guest (potassium) via charge transfer.

Plain graphite has only delocalised electrons due to the sp2 hybridized carbon atoms.  In comparison, KC8 has a higher electrical conductivity thanks to its rapid electron exchange.   Therefore, additional delocalised electrons wander across the graphite layers while electrons available for donation are accessible on the surface.  For additional review, references 3 & 4 contain a more sophisticated description of the electronic structure of KC8.

 

Potassium graphite is an extremely strong reducing agent and has been used extensively as a catalyst in chemical synthesis.  Powdered KC8 does not dissolve in organic solvents and acts in a heterogeneous manner, exploiting its high surface area.  A portion of the potassium atoms located at the intercalated edges are easier to access for the reaction.  These atoms have a reduction potential similar to that of metallic potassium.  The KC8 behaviour is in accordance with the chemistry of free potassium.  Many papers cite the successful use of KC8 for synthetic properties.  The strong reducing ability of KC8 can be utilized for purposes such as the formation of multiple bonds between elements, polymerisation catalysis, coupling reactions in organic synthesis, and the construction of various organometallic complexes.5-11

 For more details, technical notes, safety data sheet and certificates of analysis or talk to us on 01223 873028 or email enquiries@www.strem.co.uk

References:

  1. Synthetic Metals, 1995, 74, 201.
  2. J. Chem. Phys., 1965, 43, 1201.
  3. Phys. Stat. Sol., 1996, 196, 131.
  4. Phys. Stat. Sol., 2009, 79, 205106.
  5. Organometallics, 2007, 26, 4737.
  6. J. Am. Chem. Soc.,2007, 129, 12412.
  7. J. Am. Chem. Soc., 2014, 136, 5460.
  8. ACS Cent. Sci., 2017, 3, 217.
  9. Angew. Chem. Int. Ed., 2018, 57, 1874.
  10. Inorg. Chem., 2018, 57, 20.
  11. Chem. Eur. J., 2018, 24, 826.

 

Products mentioned in this blog and related products:

19-1935: Potassium graphite KC8 [12081-88-8]

19-1990: Potassium (99.95%) (breakseal ampoule) [7440-09-7]

19-1910: Potassium sodium alloy 78:22 (99.95%) [11135-81-2]

93-1990: Potassium (99.95%) (prescored ampoule) [7440-09-7]

 

Additional literature available:

Materials for Battery Applications Redox Shuttles & Electrolyte Solvents

 [metaslider id=164]

Fig. 1. Simplified structure of potassium intercalated graphite KC8:
(a) 2D projection and (b) 3D side view