freakJoe Posted May 24, 2016 Share Posted May 24, 2016 Which of these molecules is the most basic? NH3, NH2CH3, NH2NH2 or NH2OH? Link to comment Share on other sites More sharing options...
hypervalent_iodine Posted May 24, 2016 Share Posted May 24, 2016 I assume this is homework? If so, what do you think? Which part of the molecule is responsible for it being basic? Link to comment Share on other sites More sharing options...
freakJoe Posted May 25, 2016 Author Share Posted May 25, 2016 It is a part of theoretical investigation... computational chemistry... and i would like to compare calculation results with some theories. I am not sure if i am correct, but i was thinking about the nature of the group attached to NH2. Is it possible, that thanks to -CH3 substituent, which push electrones towards N atom, it makes the molecule more basic? It would tend to accept extra proton more then for example NH2OH, where -OH group withdraw the electrons...? Link to comment Share on other sites More sharing options...
BabcockHall Posted May 25, 2016 Share Posted May 25, 2016 One thing to be aware of in comparing the basicities of ammonia and gradually more methyl-substituted amines is that one has to specify gas-phase versus in solution. The order of basicities is different. Link to comment Share on other sites More sharing options...
John Cuthber Posted May 26, 2016 Share Posted May 26, 2016 It depends on the solvent (or lack of one). Link to comment Share on other sites More sharing options...
freakJoe Posted May 27, 2016 Author Share Posted May 27, 2016 no solvent and water? Link to comment Share on other sites More sharing options...
BabcockHall Posted May 27, 2016 Share Posted May 27, 2016 (edited) no solvent and water? Gas-phase acidities are obviously measured in the complete absence of solvent (my recollection is that mass spectrometry is involved, but I don't recall any details). Many pKa values are measured in water, but many others are tabulated in DMSO. With respect to primary, secondary, and tertiary amines, the relative order of pKa values is affected by how well the conjugate acid (which is a cation) is solvated by water, as well as electronic effects that are intrinsic to the cation. Edited May 27, 2016 by BabcockHall Link to comment Share on other sites More sharing options...
Albert hofmann Posted June 29, 2016 Share Posted June 29, 2016 (edited) in my opinion form left to right of increase. Because basicity is mean to, localize and feed consist of electrons. So Nh2oh the most basic i cant exactly explain im sorry i am not Good about english writting Edited June 29, 2016 by Albert hofmann Link to comment Share on other sites More sharing options...
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