66:-like geometries: the central C=N unit is nearly coplanar with all four substituents. Unsymmetrical iminium cations can exist as cis and trans isomers. The C=N bonds, which are near 129 picometers in length, are shorter than C-N single bonds. Cis/trans isomers are observed. The C=N distance is slightly shorter in iminium cations than in the parent imine, and computational studies indicate that the C=N bonding is also stronger in iminium vs imine, although the C=N distance contracts only slightly. These results indicate that the barrier for rotation is higher than in the parent imines.
167:
186:
20:
55:
246:
Unsymmetrical iminium cations undergo cis-trans isomerization. The isomerization is catalyzed by nucleophiles, which add to the unsaturated carbon, breaking the C=N double bond.
415:
Johnson, James E.; Morales, Nora M.; Gorczyca, Andrea M.; Dolliver, Debra D.; McAllister, Michael A. (2001). "Mechanisms of Acid-Catalyzed Z/E Isomerization of Imines".
570:
C. Schmit; J. B. Falmagne; J. Escudero; H. Vanlierde; L. Ghosez (1990). "A General
Synthesis of Cyclobutanones from Olefins and Tertiary Amides: 3-Hexylcyclobutanone".
630:
354:
397:
384:
Guido M. Böttger Roland Fröhlich Ernst-Ulrich Würthwein (2000). "Electrophilic
Reactivity of a 2-Azaallenium and of a 2-Azaallylium Ion".
182:
reacts with amino acids to give iminium derivatives. Many iminium salts are encountered in synthetic organic chemistry.
450:
Wang, Youliang; Poirier, Raymond A. (1997). "Factors That
Influence the CN Stretching Frequency in Imines".
671:
58:
Structure of the cation in the salt OTf illustrating the near planarity of the iminium functional group.
666:
335:
280:
290:
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236:
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They also are generated by the condensation of secondary amines with ketones or aldehydes:
8:
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270:
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Erkkilä, Anniinä; Majander, Inkeri; Pihko, Petri M. (2007). "Iminium
Catalysis".
398:
10.1002/(SICI)1099-0690(200004)2000:8<1589::AID-EJOC1589>3.0.CO;2-T
39:
569:
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639:, 2nd ed. (the "Gold Book") (1997). Online corrected version: (2006–) "
617:
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363:, 2nd ed. (the "Gold Book") (1997). Online corrected version: (2006–) "
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372:
166:
506:
436:
75:
547:
E. F. Kleinman (2004). "Dimethylmethyleneammonium Iodide and
Chloride".
79:
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428:
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Iminium salts hydrolyse to give the corresponding ketone or aldehyde:
171:
147:
This rapid, reversible reaction is one step in "iminium catalysis".
325:
155:
599:"Iminium Ion-Based Diels–Alder Reactions: N-Benzyl-2-Azanorborene"
185:
63:
35:
414:
19:
330:
83:
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Iminium compounds are intermediates in the vision cycle of
150:
More exotic routes to iminium cations are known, e.g. from
520:
Hafner, Klaus; Meinhardt, Klaus-Peter (1984). "Azulene".
54:
46:. They are common in synthetic chemistry and biology.
484:
16:
Polyatomic ion of the form >C=N< and charge +1
235:Iminium cations are reduced to the amines, e.g. by
658:
519:
549:Encyclopedia of Reagents for Organic Synthesis
546:
193:" is a well known example of an iminium salt.
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239:. Iminium cations are intermediates in the
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178:Iminium derivatives are common in biology.
23:The general structure of an iminium cation
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250:Named reactions involving iminium species
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597:Grieco, P. A.; Larsen, S. D. (1990).
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386:European Journal of Organic Chemistry
452:The Journal of Physical Chemistry A
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636:Compendium of Chemical Terminology
360:Compendium of Chemical Terminology
14:
683:
551:. New York: J. Wiley & Sons.
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417:The Journal of Organic Chemistry
74:Iminium cations are obtained by
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312:C=N. They form a subclass of
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308:have the general structure R
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49:
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42:with the general structure
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336:Quaternary ammonium cation
281:Stephen aldehyde synthesis
243:of ketones and aldehydes.
618:10.15227/orgsyn.068.0206
584:10.15227/orgsyn.069.0199
557:10.1002/047084289X.rd346
534:10.15227/orgsyn.062.0134
291:Vilsmeier-Haack reaction
286:Stork enamine alkylation
276:Pictet-Spengler reaction
649:10.1351/goldbook.I02964
373:10.1351/goldbook.I02958
237:sodium cyanoborohydride
95:+ H → [R'NH=CR
261:Beckmann rearrangement
256:Aza-Cope rearrangement
194:
175:
152:ring-opening reactions
62:Iminium cations adopt
59:
24:
188:
169:
130:NH + H ⇌ [R'
57:
22:
108:+ R → [R'RN=CR
464:1997JPCA..101..907W
241:reductive amination
180:Pyridoxal phosphate
672:Chemistry suffixes
195:
191:Eschenmoser's salt
176:
60:
25:
667:Functional groups
606:Organic Syntheses
522:Organic Syntheses
499:10.1021/cr068388p
472:10.1021/jp9617332
429:10.1021/jo010067k
423:(24): 7979–7985.
365:iminium compounds
295:Vilsmeier reagent
29:organic chemistry
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641:iminylium ions
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458:(5): 907–912.
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314:nitrenium ions
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44:[RRC=NRR]
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76:protonation
661:Categories
572:Org. Synth
342:References
227:] + O=CR
162:Occurrence
80:alkylation
487:Chem. Rev
198:Reactions
172:rhodopsin
70:Formation
50:Structure
507:18072802
437:11722194
326:Ammonium
320:See also
156:pyridine
612:: 206.
578:: 199.
528:: 134.
460:Bibcode
215:] + H
138:] + H
33:iminium
505:
435:
207:[R
104:R'N=CR
91:R'N=CR
84:imines
64:alkene
36:cation
631:IUPAC
602:(PDF)
355:IUPAC
331:Imine
126:+ R'
38:is a
31:, an
503:PMID
433:PMID
390:2000
293:and
211:N=CR
134:N=CR
122:O=CR
78:and
645:doi
643:".
614:doi
580:doi
553:doi
530:doi
495:doi
491:107
468:doi
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367:".
154:of
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223:NH
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310:2
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174:.
142:O
140:2
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132:2
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110:2
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97:2
93:2
Text is available under the Creative Commons Attribution-ShareAlike License. Additional terms may apply.
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