Decalin

  • Decahydronaphthaline
  • Decalin ®
  • Naphthan
  • Naphthalan
  • Perhydronaphthalin
  • Bicyclo [ 4.4.0 ] decane
  • 91-17-8 (mixture of isomers )
  • 493-01-6 (cis- decalin )
  • 493-02-7 (trans- decalin )

Colorless liquid with a camphor - smell or mentholartigem

Liquid

  • 0.88 g · cm -3 ( mixture of isomers)
  • 0.90 g · cm -3 ( cis)
  • 0.87 g · cm -3 ( trans)
  • -40 ° C ( mixture of isomers)
  • -30.4 ° ​​C ( cis)
  • -43 ° C ( trans)

1.27 hPa (20 ° C, mixture of isomers )

Insoluble in water (0.89 mg · l-1 at 25 ° C)

Risk

Template: Infobox chemical / molecular formula search available

Decalin (also decahydronaphthaline, Perhydronaphthalin, bicyclo [ 4.4.0 ] decane ) is a colorless liquid. It is produced by catalytic hydrogenation of naphthalene and used as a solvent ( for example, shoe creams ). Depending on the linkage geometry of the two cyclohexane rings there are two isomeric decalins, the cis- decalin ( hydrogen atoms on the, Brückenkopf' - carbon atoms are cis to each other) and the trans - decalin. Decalin is a bicyclic alkane and belongs to the parent group of the hydrocarbons.

The technical product is usually a mixture of isomers.

Properties

The colorless, low-volatility liquid has a camphoraceous odor. Technical isomer melts at about -40 ° C and boils at about 190 ° C, and is flammable. The two geometric isomers have different physical properties, the melting point of the trans-isomer is at -30 ° C, the boiling point at 187 ° C and the density 0.8700 g / ml; the cis isomer melts at -43 ° C and boils at 196 ° C and has a density of 0.8963 g / ml. Due to the boiling point difference Walter Hückel could the two isomers separated by careful distillation in 1925. The trans form is by 8.4 kJ / mol lower in energy than the cis form. Decalin is almost insoluble in water, with most of the hydrocarbons, acetone and benzene, it is miscible.

Decalin is irritating to skin and mucous membranes, is easily absorbed through the skin and is slightly hazardous for water (WGK 1).

Cis- decalin has two Sesselkonformere present on a ring -type flip balanced. In two conformers of the second six-membered ring on the one axial side and on the other equatorially linked so that both flip- ring conformers are stable. With trans-decalin in a stable six-membered ring chair conformer of the second two equatorial bonds is attached. After a hypothetical ring flip these bonds would be available axially. This conformation is not realized, as the second six-membered ring would have to be expanded for it too far. therefore, trans - decalin has only one chair conformer, while cis- decalin occurs in two Sesselkonformeren.

CAS registry number Vapor pressure Dangerous Substances Directive (67/548/EEC) Shoe polish Chemical equilibrium CRC Handbook of Chemistry and Physics Integrated Authority File
190894
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