dicyclopentadiene
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{{Chembox
| Verifiedfields = changed
| Watchedfields = changed
| verifiedrevid = 444658035
| Name = Dicyclopentadiene
| Reference = Merck Index, 11th Edition, 2744
| ImageFile = Di-Cyclopentadiene ENDO & EXO V.2.svg
| ImageName = Stereo wireframe model of dicyclopentadiene.
| ImageCaption = endo‑Dicyclopentadiene (left) exo‑Dicyclopentadiene (right)
| ImageFile1 = Dicyclopentadiene-3D-balls.png
| ImageName1 = Ball and stick model of dicyclopentadiene
| ImageCaption1 = Ball-and-stick model of endo‑Dicyclopentadiene
| IUPACName = Tricyclo[5.2.1.02,6]deca-3,8-diene
| OtherNames = 1,3-Dicyclopentadiene, Bicyclopentadiene, 3a,4,7,7a-Tetrahydro-1H-4,7-methanoindene {{bulleted list |endo isomer: (3aR*,4S*,7R*,7aS*)- | exo isomer: (3aS*,4S*,7R*,7aR*)- }}
| SystematicName =
| Section1 = {{Chembox Identifiers
| Abbreviations = DCPD
| StdInChI_Ref = {{stdinchicite|correct|chemspider}}
| StdInChI = 1S/C10H12/c1-2-9-7-4-5-8(6-7)10(9)3-1/h1-2,4-5,7-10H,3,6H2
| StdInChIKey_Ref = {{stdinchicite|correct|chemspider}}
| StdInChIKey = HECLRDQVFMWTQS-UHFFFAOYSA-N
| CASNo = 1755-01-7
| CASNo_Comment = (endo- form)
| CASNo_Ref = {{cascite|correct|CAS}}
| CASNo1_Ref = {{cascite|correct|CAS}}
| CASNo1 = 77-73-6
| CASNo1_Comment = (non-specific)
| CASNo2 = 933-60-8
| CASNo2_Comment = (exo- form)
| UNII_Ref = {{fdacite|correct|FDA}}
| UNII = 88Z4HUV8LI
| PubChem = 6492
| PubChem1 = 6428576
| PubChem1_Comment = (6R)
| PubChem2 = 10396885
| PubChem2_Comment = (1S,7R)
| ChemSpiderID = 6247
| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}
| ChemSpiderID1_Ref = {{chemspidercite|correct|chemspider}}
| ChemSpiderID1 = 24532442
| ChemSpiderID1_Comment = (2H12)
| ChemSpiderID2_Ref = {{chemspidercite|correct|chemspider}}
| ChemSpiderID2 = 4933978
| ChemSpiderID2_Comment = (6R)
| ChemSpiderID3_Ref = {{chemspidercite|correct|chemspider}}
| ChemSpiderID3 = 8572323
| ChemSpiderID3_Comment = (1S,7R)
| EINECS = 201-052-9
| UNNumber = UN 2048
| KEGG_Ref = {{keggcite|correct|kegg}}
| KEGG = C14411
| MeSHName = Dicyclopentadiene
| RTECS = PC1050000
| SMILES = C1C=CC2C1C3CC2C=C3
| InChI = 1/C10H12/c1-2-9-7-4-5-8(6-7)10(9)3-1/h1-2,4-5,7-10H,3,6H2
| InChIKey = HECLRDQVFMWTQS-UHFFFAOYAO
| Beilstein = 1904092
}}
| Section2 = {{Chembox Properties
| Formula = C10H12
| MolarMass = 132.20 g/mol
| Density = 0.978 g/cm3
| MeltingPtC = 32.5
| BoilingPtC = 170
| Appearance = Colorless, crystalline solid
| Odor = camphor-like
| SolubleOther = very soluble in ethyl ether, ethanol
soluble in acetone, dichloromethane, ethyl acetate, n-hexane, toluene
| VaporPressure = 180 Pa (20 °C)
| LogP = 2.78
}}
| Section3 =
| Section4 =
| Section5 =
| Section6 =
| Section7 = {{Chembox Hazards
| FlashPtC = 32
| AutoignitionPtC = 503
| NFPA-H = 1
| NFPA-F = 3
| NFPA-R = 1
| PEL = none{{PGCH|0204}}
}}
}}
Dicyclopentadiene, abbreviated DCPD, is a chemical compound with formula {{chem2|C10H12}}. At room temperature, it is a white brittle wax, although lower purity samples can be straw coloured liquids. The pure material smells somewhat of soy wax or camphor, with less pure samples possessing a stronger acrid odor. Its energy density is 10,975 Wh/l.
Dicyclopentadiene is a co-produced in large quantities in the steam cracking of naphtha and gas oils to ethylene. The major use is in resins, particularly, unsaturated polyester resins. It is also used in inks, adhesives, and paints.
The top seven suppliers worldwide together had an annual capacity in 2001 of 179 kilotonnes (395 million pounds).
DCPD was discovered in 1885 as a {{chem2|C10H12}} hydrocarbon among the products of pyrolysis of phenol by Henry Roscoe, who didn't identify the structure (that was made during the following decade) but accurately assumed that it was a dimer of some {{chem2|C5H6}} hydrocarbon.{{cite journal | pmc=8222071 | year=2021 | last1=Levandowski | first1=B. J. | last2=Raines | first2=R. T. | title=Click Chemistry with Cyclopentadiene | journal=Chemical Reviews | volume=121 | issue=12 | pages=6777–6801 | doi=10.1021/acs.chemrev.0c01055 | pmid=33651602 }}{{Cite journal |last=Roscoe |first=Henry E. |date=1885 |title=Note on the spontaneous polymerisation of volatile hydrocarbons at the ordinary atmospheric temperature |url=https://books.google.com/books?id=pbYxAAAAYAAJ&pg=PA669 |journal=Journal of the Chemical Society, Transactions |language=en |volume=47 |pages=669–671 |doi=10.1039/CT8854700669 |issn=0368-1645}}
History and structure
For many years the structure of dicyclopentadiene was thought to feature a cyclobutane ring as the fusion between the two subunits. Through the efforts of Alder and coworker, the structure was deduced in 1931.{{cite book |doi=10.1002/0471264180.or012.01|chapter=Cyclobutane Derivatives from Thermal Cycloaddition Reactions |title=Organic Reactions |year=2011 |last1=Roberts |first1=John D. |last2=Sharts |first2=Clay M. |pages=1–56 |isbn=978-0471264187 }}
The spontaneous dimerization of neat cyclopentadiene at room temperature to form dicyclopentadiene proceeds to around 50% conversion over 24 hours and yields the endo isomer in better than 99:1 ratio as the kinetically favored product (about 150:1 endo:exo at 80 °C).{{Cite journal|last1=Xu|first1=Rui|last2=Jocz|first2=Jennifer N.|last3=Wiest|first3=Lisa K.|last4=Sarngadharan|first4=Sarath C.|last5=Milina|first5=Maria|last6=Coleman|first6=John S.|last7=Iaccino|first7=Larry L.|last8=Pollet|first8=Pamela|last9=Sievers|first9=Carsten|last10=Liotta|first10=Charles L.|date=2019-09-05|title=Cyclopentadiene Dimerization Kinetics in the Presence of C5 Alkenes and Alkadienes|journal=Industrial & Engineering Chemistry Research|volume=58|issue=50|pages=22516–22525|doi=10.1021/acs.iecr.9b04018|s2cid=202876152 |issn=0888-5885}} However, prolonged heating results in isomerization to the exo isomer. The pure exo isomer was first prepared by base-mediated elimination of hydroiodo-exo-dicyclopentadiene.{{Cite journal|last1=Bartlett|first1=Paul D.|last2=Goldstein|first2=Irving S.|date=1947-10-01|title=exo-Dicyclopentadiene|journal=Journal of the American Chemical Society|volume=69|issue=10|pages=2553|doi=10.1021/ja01202a501|bibcode=1947JAChS..69.2553B |issn=0002-7863}} Thermodynamically, the exo isomer is about 0.7 kcal/mol more stable than the endo isomer.{{Cite journal|date=2016-11-01|title=Prediction of heat of formation for exo-Dicyclopentadiene|journal=Journal of Loss Prevention in the Process Industries|language=en|volume=44|pages=433–439|doi=10.1016/j.jlp.2016.10.015|issn=0950-4230|last1=Narayan|first1=Adithyaram|last2=Wang|first2=Beibei|last3=Nava Medina|first3=Ilse Belen|last4=Mannan|first4=M. Sam|last5=Cheng|first5=Zhengdong|last6=Wang|first6=Qingsheng|bibcode=2016JLPPI..44..433N }} The exo isomer also has a lower reported melting point of 19°C.{{cite journal |last1=Jamróz |first1=Małgorzata E |last2=Gałka |first2=Sławomir |last3=Dobrowolski |first3=Jan Cz |title=On dicyclopentadiene isomers |journal=Journal of Molecular Structure: THEOCHEM |date=September 2003 |volume=634 |issue=1–3 |pages=225–233 |doi=10.1016/S0166-1280(03)00348-8}} Both isomers are chiral.
Reactions
Above 150 °C, dicyclopentadiene undergoes a retro-Diels–Alder reaction at an appreciable rate to yield cyclopentadiene. The reaction is reversible and at room temperature cyclopentadiene dimerizes over the course of hours to re-form dicyclopentadiene. Cyclopentadiene is a useful diene in Diels–Alder reactions as well as a precursor to metallocenes in organometallic chemistry. It is not available commercially as the monomer, due to the rapid formation of dicyclopentadiene; hence, it must be prepared by "cracking" the dicyclopentadiene (heating the dimer and isolating the monomer by distillation) shortly before it is needed.
The thermodynamic parameters of this process have been measured. At temperatures above about 125 °C in the vapor phase, dissociation to cyclopentadiene monomer starts to become thermodynamically favored (the dissociation constant Kd = {{nowrap|[cyclopentadiene]2 / [dicyclopentadiene] > 1}}). For instance, the values of Kd at 149 °C and 195 °C were found to be 277 and 2200, respectively.{{Cite journal|last1=Wilson|first1=Philip J.|last2=Wells|first2=Joseph H.|date=1944-02-01|title=The Chemistry and Utilization of Cyclopentadiene.|journal=Chemical Reviews|volume=34|issue=1|pages=1–50|doi=10.1021/cr60107a001|issn=0009-2665}} By extrapolation, Kd is on the order of 10–4 at 25 °C, and dissociation is disfavored. In accord with the negative values of ΔH° and ΔS° for the Diels–Alder reaction, dissociation of dicyclopentadiene is more thermodynamically favorable at high temperatures. Equilibrium constant measurements imply that ΔH° = –18 kcal/mol and ΔS° = –40 eu for cyclopentadiene dimerization.{{Cite journal|last1=Lenz|first1=Terry G.|last2=Vaughan|first2=John D.|date=1989-02-01|title=Employing force-field calculations to predict equilibrium constants and other thermodynamic properties for the dimerization of 1,3-cyclopentadiene|journal=The Journal of Physical Chemistry|volume=93|issue=4|pages=1592–1596|doi=10.1021/j100341a081|issn=0022-3654}}
Dicyclopentadiene polymerizes. Copolymers are formed with ethylene or styrene. The "norbornene double bond" participates.{{cite journal | last1 = Li | first1 = Xiaofang | last2 = Hou | first2 = Zhaomin | title = Scandium-Catalyzed Copolymerization of Ethylene with Dicyclopentadiene and Terpolymerization of Ethylene, Dicyclopentadiene, and Styrene | journal = Macromolecules | volume = 38 | pages = 6767 | year = 2005 | doi = 10.1021/ma051323o | issue = 16| bibcode = 2005MaMol..38.6767L }} Using ring-opening metathesis polymerization a homopolymer polydicyclopentadiene is formed.
Hydroformylation of DCP gives the dialdehyde called TCD dialdehyde (TCD = tricyclodecane). This dialdehyde can be oxidized to the dicarboxylic acid and to a diol. All of these derivatives have some use in polymer science.{{Ullmann|last1=Kohlpaintner |first1=Christian |last2=Schulte |first2=Markus |last3=Falbe |first3=Jürgen |last4=Lappe |first4=Peter |last5=Weber |first5=Jürgen |title=Aldehydes, Aliphatic|year=2008|doi= 10.1002/14356007.a01_321.pub2}}
Hydrogenation of dicyclopentadiene gives tetrahydrodicyclopentadiene ({{chem|C|10|H|16}}), which is a component of jet fuel JP-10,{{cite web |title=Combustion Chemistry |url=https://chem.utah.edu/directory/anderson/research-group/CombustChem.php |website=Department of Chemistry, College of Science, the University of Utah |publisher=The University of Utah |access-date=12 January 2022}} and rearranges to adamantane{{OrgSynth | title = Adamantane | last1=Schleyer |first1=Paul von R. |last2=Donaldson |first2=M. M. |last3=Nicholas |first3=R. D. |last4=Cupas |first4=C. | prep = cv5p0016 | collvol = 5 | collvolpages = 16 | year = 1973}}{{Ullmann |last1=Hönicke |first1=Dieter |last2=Födisch |first2=Ringo |last3=Claus |first3=Peter |last4=Olson |first4=Michael |title=Cyclopentadiene and Cyclopentene|year=2002|doi=10.1002/14356007.a08_227}} with aluminium chloride or acid at elevated temperature.
References
External links
- [https://web.archive.org/web/20110716024445/http://siri.org/msds/f2/bzk/bzkxs.html MSDS for dicyclopentadiene]
- [http://www.inchem.org/documents/icsc/icsc/eics0873.htm Inchem fact sheet for dicyclopentadiene]
- [https://www.cdc.gov/niosh/npg/npgd0204.html CDC — NIOSH Pocket Guide to Chemical Hazards]
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