Diphenylethylenediamine

Diphenylethylenediamine
Names
	Preferred IUPAC name 1,2-Diphenylethane-1,2-diamine
	Other names 1,2-Diphenyl-1,2-diaminoethane; DPEN; Stilbenediamine; stien
Identifiers
CAS Number	35132-20-8 ;
3D model (JSmol)	Interactive image;
ChEMBL	ChEMBL467308 ;
ChemSpider	5305408 ;
PubChem CID	6931238;
UNII	JZ5DV7MKY6 ;
CompTox Dashboard (EPA)	DTXSID90915119 ;
	InChI InChI=1S/C14H16N2/c15-13(11-7-3-1-4-8-11)14(16)12-9-5-2-6-10-12/h1-10,13-14H,15-16H2/t13-,14-/m0/s1 Key: PONXTPCRRASWKW-KBPBESRZSA-N ; InChI=1/C14H16N2/c15-13(11-7-3-1-4-8-11)14(16)12-9-5-2-6-10-12/h1-10,13-14H,15-16H2/t13-,14-/m0/s1 Key: PONXTPCRRASWKW-KBPBESRZBK;
	SMILES N[C@@H](c1ccccc1)[C@H](c2ccccc2)N;
Properties
Chemical formula	C14H16N2
Molar mass	212.29 g/mol
Appearance	White solid
Melting point	79 to 83 °C (174 to 181 °F; 352 to 356 K)
Solubility in water	Slightly
Related compounds
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). verify (what is ?) Infobox references

1,2-Diphenyl-1,2-ethylenediamine, DPEN, is an organic compound with the formula H₂NCHPhCHPhNH₂, where Ph is phenyl (C₆H₅). DPEN exists as three stereoisomers: meso and two enantiomers S,S- and R,R-. The chiral diastereomers are used in asymmetric hydrogenation. Both diastereomers are bidentate ligands.^[1]

Preparation and optical resolution

1,2-Diphenyl-1,2-ethylenediamine can be prepared from benzil by reductive amination.^[2] DPEN can be obtained as both the chiral and meso diastereomers, depending on the relative stereochemistry of the two CHPhNH₂ subunits. The chiral diastereomer, which is of greater value, can be resolved into the R,R- and S,S- enantiomers using tartaric acid as the resolving agent. In methanol, the R,R enantiomer has a specific rotation of [α]₂₃ +106±1°.

Asymmetric catalysis

N-tosylated derivative, TsDPEN, is a ligand precursor for catalysts for asymmetric transfer hydrogenation. For example, (cymene)Ru(S,S-TsDPEN) catalyzes the hydrogenation of benzil into (R,R)-hydrobenzoin. In this reaction, formate serves as the source of H₂:^[3]^[4]

PhC(O)C(O)Ph + 2 H₂ → PhCH(OH)CH(OH)Ph (R,R isomer)

This transformation is an example of desymmetrization, the symmetric molecule benzil is converted to the dissymmetric product.

DPEN is a key ingredients of Ryōji Noyori's 2nd generation ruthenium-based chiral hydration catalyst, for which he earned the Nobel Prize in Chemistry in 2001.

References

^ Goodgame, D. M. L.; Hitchman, M. A. (1968). "Stilbenediamine complexes of nickel(II)". Inorganic Chemistry. 7 (7): 1404–1407. doi:10.1021/ic50065a028.
^ S. Pikul, E. J. Corey (1993). "(1R,2R)-(+)- and (1S,2S)-(−)-1,2-Diphenyl-1,2-Ethylenediamine". Organic Syntheses. 71: 22. doi:10.15227/orgsyn.071.0022.
^ Takao Ikariya, Shohei Hashiguchi, Kunihiko Murata, Ryōji Noyori (2005). "Preparation of Optically Active (R,R)-Hydrobenzoin from Benzoin or Benzil". Organic Syntheses. 82: 10. doi:10.15227/orgsyn.082.0010.{{cite journal}}: CS1 maint: multiple names: authors list (link)
^ Chen, Fei; Ding, Zi-Yuan; He, Yan-Mei; Fan, Qing-Hua (2015). "Synthesis of Optically Active 1,2,3,4-Tetrahydroquinolines via Asymmetric Hydrogenation Using Iridium-Diamine Catalyst". Org. Synth. 92: 213–226. doi:10.15227/orgsyn.092.0213.

[1] Goodgame, D. M. L.; Hitchman, M. A. (1968). "Stilbenediamine complexes of nickel(II)". Inorganic Chemistry. 7 (7): 1404–1407. doi:10.1021/ic50065a028.

[2] S. Pikul, E. J. Corey (1993). "(1R,2R)-(+)- and (1S,2S)-(−)-1,2-Diphenyl-1,2-Ethylenediamine". Organic Syntheses. 71: 22. doi:10.15227/orgsyn.071.0022.

[3] Takao Ikariya, Shohei Hashiguchi, Kunihiko Murata, Ryōji Noyori (2005). "Preparation of Optically Active (R,R)-Hydrobenzoin from Benzoin or Benzil". Organic Syntheses. 82: 10. doi:10.15227/orgsyn.082.0010.{{cite journal}}: CS1 maint: multiple names: authors list (link)

[4] Chen, Fei; Ding, Zi-Yuan; He, Yan-Mei; Fan, Qing-Hua (2015). "Synthesis of Optically Active 1,2,3,4-Tetrahydroquinolines via Asymmetric Hydrogenation Using Iridium-Diamine Catalyst". Org. Synth. 92: 213–226. doi:10.15227/orgsyn.092.0213.

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