| Revision as of 09:59, 24 June 2010 editRifleman 82 (talk | contribs)Extended confirmed users32,436 edits →Reactions: silyl ethers |
Latest revision as of 11:13, 13 January 2024 edit Maxim Masiutin (talk | contribs)Extended confirmed users, IP block exemptions, Pending changes reviewers31,104 edits Alter: journal, title, chapter. Added isbn. |
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{{chembox |
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| verifiedrevid = 322372364 |
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| verifiedrevid = 369887408 |
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|ImageFile=Dhp.png |
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| Name = Dihydropyran |
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|ImageSize=100px |
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|IUPACName=3,4-Dihydro-2H-pyran |
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| ImageFile1 = Structural formula of 3,4-dihydro-2H-pyran.svg |
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| ImageSize1 = 90px |
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|OtherNames= Dihydropyran |
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| ImageName1 = 3,4-dihydropyran skelet |
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|Section1= {{Chembox Identifiers |
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| ImageCaptionL2 = 3,4-dihydropyran |
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| InChI = 1/C5H8O/c1-2-4-6-5-3-1/h2,4H,1,3,5H2 |
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| PIN=3,4-Dihydro-2''H''-pyran |
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| OtherNames= 2,3-Dihydro-4''H''-pyran, DHP |
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|Section1={{Chembox Identifiers |
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| InChI = 1/C5H8O/c1-2-4-6-5-3-1/h2,4H,1,3,5H2 |
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| InChIKey = BUDQDWGNQVEFAC-UHFFFAOYAJ |
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| InChIKey = BUDQDWGNQVEFAC-UHFFFAOYAJ |
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| CASNo_Ref = {{cascite}} |
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| CASNo_Ref = {{cascite|correct|CAS}} |
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| CASNo=110-87-2 |
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| CASNo=110-87-2 |
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| PubChem= 8080 |
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| PubChem= 8080 |
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| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}} |
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| ChemSpiderID = 7789 |
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| ChemSpiderID = 7789 |
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| SMILES = O1\C=C/CCC1 |
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| EC_number = 203-810-4 |
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| ChEMBL = 3184439 |
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| UNNumber = 2376 |
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| UNII = T6V9N71IHX |
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| SMILES = O1\C=C/CCC1 |
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| SMILES_Comment = 3,4 isomer |
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|Section2= {{Chembox Properties |
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|Section2={{Chembox Properties |
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| C=5 | H=8 | O=1 |
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| Formula=C<sub>5</sub>H<sub>8</sub>O |
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| Appearance=Colorless liquid |
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| MolarMass=84.12 |
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| Density=0.922 g/mL |
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| Appearance=colorless liquid |
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| MeltingPtC=-70 |
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| Density=0.992 g/mL at 25 °C |
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| BoilingPtC=86 |
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| MeltingPtC=-70 |
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| Solubility= |
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| BoilingPtC=86 |
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| Solubility=organic solvents |
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}} |
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|Section3= {{Chembox Hazards |
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|Section3={{Chembox Hazards |
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| MainHazards= |
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| FlashPt= |
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| FlashPt= |
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| AutoignitionPt = |
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| Autoignition= |
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| GHSPictograms = {{GHS02}}{{GHS07}} |
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| GHSSignalWord = Danger |
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| HPhrases = {{H-phrases|225|315|317|319}} |
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| PPhrases = {{P-phrases|210|233|240|241|242|243|261|264|272|280|302+352|303+361+353|305+351+338|321|332+313|333+313|337+313|362|363|370+378|403+235|501}} |
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'''2,3-Dihydropyran''' is the ] with the ] C<sub>5</sub>H<sub>8</sub>O. This cyclic ] is used to ] alcohols in ]. |
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'''3,4-Dihydropyran''' (DHP) is a ] with the ] C<sub>5</sub>H<sub>8</sub>O. The six-membered C<sub>5</sub>O ring has the unsaturation adjacent to oxygen. The isomeric 3,6-dihydropyran has a methylene separating the double bond and oxygen. DHP is used for ] for alcohols. It is a colorless liquid.<ref>{{cite journal|journal=EEROS|title=3,4-Dihydro-2H-pyran|author1=Paul Ch. Kierkus|year=2001|doi=10.1002/047084289X.rd230|isbn=0471936235 }}</ref> |
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==Preparation== |
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==Preparation== |
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Dihydropyran is prepared by the dehydration of tetrahydrofurfuryl alcohol over ] at 300-400 °C.<ref>{{OrgSynth | author = R. L. Sawyer and D. W. Andrus | title = 2,3-Dihydropyran | collvol = 3 | collvolpages = 276 | year = 1955 | prep = cv3p0276}}</ref> |
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Dihydropyran is prepared by the dehydration of ] over ] at 300–400 °C.<ref>{{OrgSynth | author = R. L. Sawyer and D. W. Andrus | title = 2,3-Dihydropyran | collvol = 3 | collvolpages = 276 | year = 1955 | prep = cv3p0276}}</ref> THFA is itself prepared from ]. |
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==Reactions== |
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==Reactions== |
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In ], the 2-tetrahydropyranyl group is used as a ] for ]s.<ref>{{OrgSynth | title = Methyl 4-Hydroxy-2-butynoate | author = R. A. Earl L. B. Townsend | collvol = 7 | collvolpages = 334 | year = 1990 | prep = cv7p0334}}</ref><ref>{{OrgSynth | title =<nowiki>Diethyl phosphonate</nowiki> | author = Arthur F. Kluge | collvol = 7 | collvolpages = 160 | year = 1990 | prep = cv7p0160}}</ref> Reaction of the alcohol with ] forms a tetrahydropyranyl ether, protecting the alcohol from a variety of reactions. The alcohol can later be restored readily by acidic ] with formation of 5-hydroxypentanal. |
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In ], the 2-tetrahydropyranyl (THP) group is used as a ] for ]s.<ref>{{OrgSynth | title = Methyl 4-Hydroxy-2-butynoate | author = R. A. Earl L. B. Townsend | collvol = 7 | collvolpages = 334 | year = 1990 | prep = cv7p0334}}</ref><ref>{{OrgSynth | title =<nowiki>Diethyl phosphonate</nowiki> | author = Arthur F. Kluge | collvol = 7 | collvolpages = 160 | year = 1990 | prep = cv7p0160}}</ref> Reaction of the alcohol with DHP forms a THP ether, protecting the alcohol from a variety of reactions. The alcohol can later be restored by acidic ], concomitant with formation of 5-hydroxypentanal.<ref>{{cite book|title = Greene's Protective Groups in Organic Synthesis|chapter = Protection for the Hydroxyl Group, Including 1,2- and 1,3-Diols|pages = 16–366|edition = 4th|last1 = Wuts|first1 = Peter G. M.|last2 = Greene|first2 = Theodora W.|doi = 10.1002/9780470053485.ch2|year = 2006|isbn = 9780470053485}}</ref> |
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== See also == |
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Various ]s are also popular protecting groups for alcohols. |
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*] |
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*] |
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==References== |
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==References== |
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{{reflist}} |
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<references/> |
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{{DEFAULTSORT:Dihydropyran, 2,3-}} |
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{{DEFAULTSORT:Dihydropyran, 2, 3-}} |
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