Nascent hydrogen

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 H2, a special state of hydrogen was postulated. It is now understood that dissolving-metal reactions occur at the metal surface, and the concept of nascent hydrogen is discounted, and even ridiculed.[1][2]

It is now understood that nascent hydrogen is hydrogen in the form of individual atoms, not paired into molecules as it is in the gaseous state. Individual atoms or ions of hydrogen are highly reactive.

History

The idea of hydrogen in the nascent state having chemical properties different from those of molecular hydrogen was developed the mid-19th century. Alexander Williamson repeatedly refers to nascent hydrogen 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]

The term "nascent hydrogen" continued to be invoked into the 20th Century.[7]

References
  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 (11): 2629–2637. doi:10.1002/asia.201200557. PMID 22952036.
  3. Williamson, Alexander William (1868). Chemistry for Students. Clarendon Press. p. 139.
  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.
  7. J. W. McCutcheon (1942). "Linoleic Acid". Org. Synth. 22: 75. doi:10.15227/orgsyn.022.0075.

Further reading
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