1,3-pentadiene

1,3-pentadienes (penta-1,3-dienes, piperylenes, 1-methyl-1,3-butadienes)
Surname	trans -1,3-pentadiene	cis -1,3-pentadiene
other names	trans -penta-1,3-diene ( E ) -1,3-pentadiene trans -piperylene ( E ) -piperylene	cis -penta-1,3-diene ( Z ) -1,3-pentadiene cis -piperylene ( Z ) -piperylene
Structural formula
CAS number	2004-70-8	1574-41-0
	504-60-9 (mixture of isomers)
PubChem	62204	643785
Molecular formula	C 5 H 8
Molar mass	68.12 g mol −1
Physical state	liquid
Brief description	colorless liquid
Melting point	−87 ° C	−141 ° C
boiling point	42 ° C	44 ° C
density	0.683 g cm −3 (25 ° C)	0.691 g cm −3 (25 ° C)
Vapor pressure	452 hPa (20 ° C)	453 hPa (20 ° C)
Refractive index	1.430 (20 ° C)	1.437 (20 ° C)
solubility	miscible with ethanol, ether, acetone and benzene
GHS labeling	danger	danger
H and P phrases	225-304-315-319-335	225-304
	no EUH phrases	no EUH phrases
	210-261-301 + 310-305 + 351 + 338-331	210-301 + 310-331

1,3-Pentadiene is an imprecise name for two chemical compounds from the group of dienes that are isomeric to one another (configuration isomers). It is also known as piperylene (a derivative of piperine ).

Another 1,3-pentadiene is the branched isomer 2-methylbutadiene ( isoprene ).

Extraction and presentation

1,3-pentadiene can be prepared by methylation of 1,3-butadiene with dimethyl sulfoxide in the presence of a base such as potassium tert -butoxide are obtained, wherein a mixture of about 80% trans - and 20% cis -1,3-pentadiene produced.

It can also be produced by a Wittig reaction from acetaldehyde , acrolein or crotonaldehyde , both the yield and the cis / trans selectivity varying depending on various factors (e.g. the starting material or the solvent used).

It is also formed in the Hofmann elimination from piperidine , which is converted into 1,4-pentadiene by repeated exhaustive methylation and subsequent elimination of trimethylamine , but which isomerized to 1,3-pentadiene under the reaction conditions.

It is also produced as a by-product of the process of separating crude C ₅ materials from pyrolysis gasoline (pygas) - both by-products of the production of ethylene .

properties

1,3-pentadiene is a colorless liquid.

use

1,3-pentadiene can be used to produce other chemical compounds such as. B. 2-methylfuran can be used. It is also used as a monomer in the manufacture of plastics, adhesives, and resins. Piperylene-based products are used particularly in modern adhesives - such as in the production of envelopes, packaging tape and diaper fasteners - as well as in road markings around the world.

Individual evidence

1. ↑ ^{a b c d e f g h} data sheet trans-1,3-pentadiene, 90% from Sigma-Aldrich , accessed on October 13, 2012 ( PDF ).
2. ↑ ^{a b c d e f} data sheet cis-1,3-pentadiene, 98% from Sigma-Aldrich , accessed on October 13, 2012 ( PDF ).
3. ↑ ^{a b} Entry on trans-1,3-pentadienes in the Hazardous Substances Data Bank , accessed October 13, 2012.
4. ↑ C. Schotten: Contribution to the knowledge of piperidine. In: Reports of the German Chemical Society 15, 1882, pp. 421-427, doi : 10.1002 / cber.18820150186 .
5. ↑ Jerome Thomas Kresse: The investigation of factors influencing the stereochemistry of the Wittig reaction (PDF; 3.9 MB), University of Florida, Diss., 1965.
6. ↑ Albert Gossauer: Structure and reactivity of biomolecules . John Wiley & Sons, 2003, ISBN 3-906390-29-2 , pp. 255 ( limited preview in Google Book search).
7. ^ ^{A b} Shell Chemicals: Piperylene product overview ( Memento from September 18, 2013 in the Internet Archive ).