Nascent hydrogen

From Wikipedia, the free encyclopedia
Jump to navigation Jump to search

Nascent hydrogen is a concept that was once invoked to explain dissolving-metal reactions, such as the Clemmensen reduction and the Bouveault–Blanc reduction. Since organic compounds do not react with hydrogen gas, which is the normal form of this element, a special, highly reactive state, of hydrogen was postulated to explain this class of hydrogenation. It is now well understood that such reactions take place at the metal surface via one-electron reduction, and the concept of nascent hydrogen is discounted, even ridiculed.[1][2]

History[edit]

The concept of hydrogen in the nascent state having chemical properties different from those of molecular hydrogen was well-established by the mid-nineteenth century. Alexander Williamson used the concept repeatedly in his textbook Chemistry for Students, for example writing of the substitution reaction of carbon tetrachloride with hydrogen to form products such as chloroform and dichloromethane that the "hydrogen must for this purpose be in the nascent state, as free hydrogen does not produce the effect".[3] Williamson also describes the use of nascent hydrogen in describing earlier work of Marcellin Berthelot.[4] Franchot published a paper on the concept in 1896,[5] which drew a strongly worded response from Tommasi who pointed to his own work that concluded "nascent hydrogen is nothing else than H + x calories".[6]

References[edit]

  1. ^ Laborda, F.; Bolea, E.; Baranguan, M. T.; Castillo, J. R. (2002). "Hydride generation in analytical chemistry and nascent hydrogen: when is it going to be over?". Spectrochim. Acta B. 57 (4): 797–802. Bibcode:2002AcSpe..57..797L. doi:10.1016/S0584-8547(02)00010-1. 
  2. ^ Fábos, Viktória; Yuen, Alexander K. L.; Masters, Anthony F.; Maschmeyer, Thomas (2012). "Exploring the myth of nascent hydrogen and its implications for biomass conversions". Chem. Asian J. 7: 2629–2637. doi:10.1002/asia.201200557. 
  3. ^ Williamson, Alexander William (1868). Chemistry for Students. Clarendon Press. 
  4. ^ Williamson, Alexander W. (1866). "Organic chemistry". The Chemical News and Journal of Physical Science. 13 (318): 14–17. 
  5. ^ Franchot, R. (1896). "Nascent hydrogen". J. Phys. Chem. 1 (2): 75–80. doi:10.1021/j150584a002. 
  6. ^ Tommasi, D. (1897). "Comment on the note of R. Franchot entitled "Nascent hydrogen"". J. Phys. Chem. 1 (9): 555. doi:10.1021/j150591a004. 

Further reading[edit]