Editing Nucleophile (section)

==== Mayr–Patz equation ====
In the Mayr–Patz equation (1994):<ref>{{cite journal | doi = 10.1002/anie.199409381| title = Scales of Nucleophilicity and Electrophilicity: A System for Ordering Polar Organic and Organometallic Reactions| journal = Angewandte Chemie International Edition in English| volume = 33| issue = 9| pages = 938| year = 1994| last1 = Mayr| first1 = Herbert| last2 = Patz| first2 = Matthias}}</ref>
:<math>\log(k) = s(N + E)</math>

The [[rate law|second order]] [[reaction rate constant]] ''k'' at 20&nbsp;°C for a reaction is related to a nucleophilicity parameter ''N'', an electrophilicity parameter ''E'', and a nucleophile-dependent slope parameter ''s''. The constant ''s'' is defined as 1 with [[2-methyl-1-pentene]] as the nucleophile.

Many of the constants have been derived from reaction of so-called [[benzhydrylium ion]]s as the [[electrophile]]s:<ref>{{cite journal | doi = 10.1021/ja010890y| pmid = 11572670| title = Reference Scales for the Characterization of Cationic Electrophiles and Neutral Nucleophiles | journal = Journal of the American Chemical Society| volume = 123| issue = 39| pages = 9500–12| year = 2001| last1 = Mayr| first1 = Herbert| last2 = Bug| first2 = Thorsten| last3 = Gotta| first3 = Matthias F| last4 = Hering| first4 = Nicole| last5 = Irrgang| first5 = Bernhard| last6 = Janker| first6 = Brigitte| last7 = Kempf| first7 = Bernhard| last8 = Loos| first8 = Robert| last9 = Ofial| first9 = Armin R| last10 = Remennikov| first10 = Grigoriy| last11 = Schimmel| first11 = Holger| s2cid = 8392147}}</ref>
:[[File:Benzhydryliumion.png|150px|benzhydrylium ions used in the determination of Mayr–Patz equation]]

and a diverse collection of π-nucleophiles:
:[[File:MayrNucleophiles.png|300px|Nucleophiles used in the determination of Mayr–Patz equation, X = tetrafluoroborate anion]].

Typical E values are +6.2 for R = [[chlorine]], +5.90 for R = [[hydrogen]], 0 for R = [[methoxy]] and −7.02 for R = [[dimethylamine]].

Typical N values with s in parentheses are −4.47 (1.32) for [[electrophilic aromatic substitution]] to [[toluene]] (1), −0.41 (1.12) for [[electrophilic addition]] to 1-phenyl-2-propene (2), and 0.96 (1) for addition to 2-methyl-1-pentene (3), −0.13 (1.21) for reaction with triphenylallylsilane (4), 3.61 (1.11) for reaction with [[2-methylfuran]] (5), +7.48 (0.89) for reaction with isobutenyltributylstannane (6) and +13.36 (0.81) for reaction with the [[enamine]] 7.<ref>An internet database for reactivity parameters maintained by the Mayr group is available at http://www.cup.uni-muenchen.de/oc/mayr/</ref>

The range of organic reactions also include [[SN2 reaction]]s:<ref name=Mayr2006>{{cite journal | doi = 10.1002/anie.200600542| pmid = 16646102| title = Towards a General Scale of Nucleophilicity?| journal = Angewandte Chemie International Edition| volume = 45| issue = 23| pages = 3869–74| year = 2006| last1 = Phan| first1 = Thanh Binh| last2 = Breugst| first2 = Martin| last3 = Mayr| first3 = Herbert| citeseerx = 10.1.1.617.3287}}</ref>
:[[File:Mayr2006.png|400px|Mayr equation also includes SN2 reactions]]

With E = −9.15 for the ''S-methyldibenzothiophenium ion'', typical nucleophile values N (s) are 15.63 (0.64) for [[piperidine]], 10.49 (0.68) for [[methoxide]], and 5.20 (0.89) for water. In short, nucleophilicities towards sp<sub>2</sub> or sp<sub>3</sub> centers follow the same pattern.