2,6-Diisopropylphenyl group

The 2,6-diisopropylphenyl group, abbreviated Dipp, is an aromatic functional group in organic chemistry. The chemical formula can be written C₆H₃((CH₃)₂CH)₂−, but it is frequently shortened to C₆H₃ iPr ₂−, similarly to the use of C₆H₂ Me ₃− for mesityl. It offers considerable steric bulk, making it of interest for researching unstable compounds and designing ligands in organometallic chemistry.

Preparation

Preparation of 2,6-diisopropylphenyl compounds from 1,3-diisopropylbenzene is impractical. Steric hindrance from the isopropyl substitutents means aromatic substitution reactions will primarily produce 1,3,5-substituted benzenes (3,5-diisopropylphenyl in functional group nomenclature).^{[ citation needed ]}

A major source of diisopropylphenyl substituents is 2,6-diisopropylaniline. Diisopropyl compounds may also be prepared from halobenzene derivatives such as 2,6-diisopropylbromobenzene. ^[1]

Applications

Diisopropyl substituents make up most of this NacNac ligand.

The diisopropylphenyl structure consists of alkane-substituted benzene, so it is not very chemically reactive. It serves instead to provide steric hindrance, limiting reactions of other nearby functional groups.

The diisopropylphenyl structure is found in many ligands calling for steric bulk. NacNac ligands can be prepared from 2,6-diisopropylaniline. Terphenyl ligands featuring two diisopropylphenyl substituents, systematically bis(diisopropylphenyl)phenyl, are capable of stabilising high-bond order compounds such as dimetallenes. ^[2] The first stable digermyne was prepared using DIPP-based terphenyl ligands. ^[3]

References

1. Knorr, Rudolf; Ruhdorfer, Jakob; Böhrer, Petra; Bronberger, Hildegard; Räpple, Edith (1994). "Sterically Congested Molecules, 11. The 2,6-Diisopropylphenyl Substituent at C=C and C=N Groups". Liebigs Annalen der Chemie (4): 433–438. doi:10.1002/jlac.199419940417.
2. Rivard, Eric; Power, Philip P. (2007). "Multiple Bonding in Heavier Element Compounds Stabilized by Bulky Terphenyl Ligands". Inorganic Chemistry. 46 (24): 10047–10064. doi:10.1021/ic700813h. PMID   17975890.
3. Stender, Matthias; Phillips, Andrew D.; Wright, Robert J.; Power, Philip P. (2002). "Synthesis and Characterization of a Digermanium Analogue of an Alkyne". Angewandte Chemie International Edition. 41 (10): 1785–1787. doi:10.1002/1521-3773(20020517)41:10<1785::AID-ANIE1785>3.0.CO;2-6. PMID   19750717.