Diels–Alder reactionChemical reactionDiels–Alder reaction, simplest exampleIn organic chemistry, the Diels–Alder reaction is a chemical reaction between a conjugateddiene and a substituted alkene, commonly termed the dienophile, to form a substituted cyclohexene derivative. It is the prototypical pericyclic reaction with a concerted mechanism; specifically, it is a thermally-allowed [4+2] cycloaddition with Woodward–Hoffmann symbol [π4s + π2s].
CyclopentadieneNames Preferred IUPAC nameCyclopenta-1,3-dieneOther names 1,3-CyclopentadienePyropentyleneIdentifiers CAS Number542-92-73D model (JSmol)Interactive imageAbbreviations CPD, HCp Beilstein Reference471171 ChEBICHEBI:30664ChemSpider7330ECHA InfoCard100.008.033EC Number208-835-4Gmelin Reference1311 MeSH1,3-cyclopentadienePubChemCID7612RTECS numberGY1000000UNII5DFH9434HFCompTox Dashboard(EPA)DTXSID0027191InChIInChI=1S/C5H6/c1-2-4-5-3-1/h1-4H,5H2Key: ZSWFCLXCOIISFI-UHFFFAOYSA-NInChI=1/C5H6/c1-2-4-5-3-1/h1-4H,5H2Key: ZSWFCLXCOIISFI-UHFFFAOYAISMILESC1C=CC=C1Properties Chemical formulaC5H6Molar mass66.103 g·mol Appearance Colourless liquid Odorirritating, terpene-like Density0.802 g/cm Melting point−90 °C; −130 °F; 183 K Boiling point39 to 43 °C; 102 to 109 °F; 312 to 316 K Solubility in waterinsoluble Vapor pressure400 mmHg (53 kPa) Acidity (pKa) 16 Conjugate baseCyclopentadienyl anionMagnetic susceptibility (χ)−44.5×10 cm/molRefractive index (nD)1.44 (at 20 °C) Structure Molecular shapePlanar Dipole moment0.419 DThermochemistry Heat capacity(C)115.3 J/(mol·K) Std molarentropy(S298)182.7 J/(mol·K) Std enthalpy offormation(ΔfH298)105.9 kJ/mol Hazards NFPA 704 (fire diamond) 230Flash point25 °C (77 °F; 298 K) Autoignitiontemperature640 °C (1,184 °F; 913 K) Lethal dose or concentration (LD, LC): LC50 (median concentration)14,182 ppm (rat, 2 h)5091 ppm (mouse, 2 h) NIOSH (US health exposure limits): PEL (Permissible)TWA 75 ppm (200 mg/m) REL (Recommended)TWA 75 ppm (200 mg/m) IDLH (Immediate danger)750 ppm Related compounds Related hydrocarbonsBenzeneCyclobutadieneCyclopenteneRelated compoundsDicyclopentadieneExcept where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).Nverify ( ?)
Stockholm Convention on Persistent Organic PollutantsInternational environmental treaty Stockholm Convention on Persistent Organic PollutantsThe logo of the Stockholm Convention SecretariatTypeUnited Nations treatySigned22 May 2001LocationStockholm, SwedenEffective17 May 2004ConditionNinety days after the ratification by at least 50 signatory statesSignatories152Parties186DepositarySecretary-General of the United NationsLanguagesArabic, Chinese, English, French, Russian, Spanishpops.int State parties to the Stockholm Convention as of 2022 Stockholm Convention on Persistent Organic Pollutants is an international environmental treaty, signed on 22 May 2001 in Stockholm and effective from 17 May 2004, that aims to eliminate or restrict the production and use of persistent organic pollutants (POPs).
Gastrointestinal tractThe gastrointestinal tract (also called the GI tract, digestive tract, gut and the alimentary canal) is the tract or passageway of the digestive system that leads from the mouth to the anus. The tract is one of the largest of the body's systems. The GI tract contains all the major organs of the digestive system, in humans and other animals, including the esophagus, stomach, and intestines.
Chemical polarityIn chemistry, polarity is a separation of electric charge leading to a molecule or its chemical groups having an electric dipole moment, with a negatively charged end and a positively charged end. Polar molecules must contain one or more polar bonds due to a difference in electronegativity between the bonded atoms. Molecules containing polar bonds have no molecular polarity if the bond dipoles cancel each other out by symmetry.
MetabolismSet of chemical reactions in organismsSimplified view of cellular metabolismMetabolism (, from Greek μεταβολή (metabolē) 'change') refers to the set of life-sustaining chemical reactions that occur within living organisms.
Persistent organic pollutantOrganic compounds that are resistant to environmental degradation Part of a series onPollutionAir pollution from a factory Air Acid rain Air quality index Atmospheric dispersion modeling Chlorofluorocarbon Combustion Exhaust gas Haze Household air pollution Global dimming Global distillation Indoor air quality Non-exhaust emissions Ozone depletion Particulate matter Persistent organic pollutant Smog Soot Volatile organic compound Biological Biological hazard Genetic Illegal logging Introduced species Invasive species Digital Information Effects of violence in mass media Electromagnetic Light Ecological Overillumination Radio spectrum Natural Ozone Radium and radon in the environment Volcanic ash Wildfire Noise Transportation Health effects from noise Marine mammals and sonar Noise barrier Noise control Soundproofing Radiation Actinides Bioremediation Depleted uranium Nuclear fission Nuclear fallout Plutonium Poisoning Radioactivity Uranium Radioactive waste Soil Agricultural Land degradation Bioremediation Defecation Electrical resistance heating Illegal mining Soil guideline values Phytoremediation Solid waste Advertising mail Biodegradable waste Brown waste Electronic waste Food waste Green waste Hazardous waste Industrial waste Landfill Litter Mining Municipal solid waste Nanomaterials Plastic Packaging waste Post-consumer waste Waste management Space Space debris Thermal Urban heat island Visual Air travel Advertising clutter Overhead power lines Traffic signs Urban blight Vandalism War Chemical warfare Herbicidal warfare Agent Orange Nuclear holocaust Nuclear fallout Nuclear famine Nuclear winter Scorched earth Unexploded ordnance War and environmental law Water Agricultural wastewater Biosolids Diseases Eutrophication Firewater Freshwater Groundwater Hypoxia Industrial wastewater Marine Monitoring Nonpoint source Nutrient Ocean acidification Oil spill Pharmaceuticals Freshwater salinization Septic tanks Sewage Shipping Sludge Stagnation Sulfur water Surface runoff Turbidity Urban runoff Water quality Wastewater Topics History Pollutants Heavy metals Paint Misc Area source Brain health and pollution Debris Dust Garbology Legacy Midden Point source Technofossil Waste Toxic Lists Diseases Law by country Most polluted cities Least polluted cities by PM2.5 Treaties Most polluted rivers Categories By country Environment portal Ecology portalvte Persistent organic pollutants (POPs) are organic compounds that are resistant to degradation through chemical, biological, and photolytic processes.
PesticideSubstance used to control pestsA self-propelled crop sprayer spraying pesticide on a fieldA crop-duster spraying pesticide on a fieldPesticides are substances that are used to controlpests. They include herbicides, insecticides, nematicides, fungicides, and many others (see table). The most common of these are herbicides, which account for approximately 50% of all pesticide use globally.
Carbon dioxideCarbon-oxygen gasNames IUPAC nameCarbon dioxideOther names Carbonic acid gasCarbonic anhydrideCarbonic dioxideCarbonic oxideCarbon(IV) oxideMethanedioneR-744 (refrigerant)R744 (refrigerant alternative spelling)Dry ice (solid phase)Identifiers CAS Number124-38-93D model (JSmol)Interactive imageInteractive imageBeilstein Reference1900390 ChEBICHEBI:16526ChEMBLChEMBL1231871ChemSpider274ECHA InfoCard100.004.271EC Number204-696-9E numberE290 (preservatives)Gmelin Reference989 KEGGD00004MeSHCarbon+dioxidePubChemCID280RTECS numberFF6400000UNII142M471B3JUN number1013 (gas), 1845 (solid) CompTox Dashboard(EPA)DTXSID4027028InChIInChI=1S/CO2/c2-1-3Key: CURLTUGMZLYLDI-UHFFFAOYSA-NInChI=1/CO2/c2-1-3Key: CURLTUGMZLYLDI-UHFFFAOYAOSMILESO=C=OC(=O)=OProperties Chemical formulaCO2Molar mass44.009 g·mol Appearance Colorless gas OdorLow concentrations: noneHigh concentrations: sharp; acidicDensity1562 kg/m (solid at 1 atm (100 kPa) and −78.5 °C (−109.3 °F))1101 kg/m (liquid at saturation −37 °C (−35 °F))1.977 kg/m (gas at 1 atm (100 kPa) and 0 °C (32 °F))Critical point (T, P) 304.128(15) K (30.978(15) °C), 7.3773(30) MPa (72.808(30) atm) Sublimationconditions194.6855(30) K (−78.4645(30) °C) at 1 atm (0.101325 MPa) Solubility in water1.45 g/L at 25 °C (77 °F), 100 kPa (0.99 atm) Vapor pressure5.7292(30) MPa, 56.54(30) atm (20 °C (293.15 K)) Acidity (pKa) Carbonic acid:pKa1 = 3.6pKa1(apparent) = 6.35pKa2 = 10.33 Magnetic susceptibility (χ)−20.5·10 cm/mol Thermal conductivity0.01662 W·m·K (300 K (27 °C; 80 °F)) Refractive index (nD)1.00045 Viscosity14.90 μPa·s at 25 °C (298 K)70 μPa·s at −78.5 °C (194.7 K)Dipole moment0 D Structure Crystal structureTrigonal Point groupD∞hMolecular shapeLinearThermochemistry Heat capacity(C)37.135 J/(K·mol) Std molarentropy(S298)214 J·mol·K Std enthalpy offormation(ΔfH298)−393.5 kJ·mol Pharmacology ATC codeV03AN02 (WHO) Hazards GHS labelling: PictogramsSignal wordWarningHazard statementsH280, H281Precautionary statementsP282, P336+P317, P403, P410+P403NFPA 704 (fire diamond) 200SALethal dose or concentration (LD, LC): LCLo (lowest published)90,000 ppm (162,000 mg/m) (human, 5 min) NIOSH (US health exposure limits): PEL (Permissible)TWA 5000 ppm (9000 mg/m) REL (Recommended)TWA 5000 ppm (9000 mg/m), ST 30,000 ppm (54,000 mg/m) IDLH (Immediate danger)40,000 ppm (72,000 mg/m) Safety data sheet (SDS) Sigma-AldrichRelated compounds Other anionsCarbon disulfideCarbon diselenideCarbon ditellurideOther cationsSilicon dioxideGermanium dioxideTin dioxideLead dioxideTitanium dioxideZirconium dioxideHafnium dioxideCerium dioxideThorium dioxideRelated carbonoxidesSee OxocarbonRelated compoundsCarbonic acidCarbonyl sulfideCarbonyl selenideSupplementary data page Carbon dioxide (data page)Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).N verify ( ?)
Flame retardantSubstance applied to items to slow burning or delay ignitionOpen-flame tests compare the flammability of untreated polyurethane foam (top) and an identical foam sample surface treated with a sandwich-like coating incorporating layered double hydroxides.
DyeA dye is a substance that is soluble in some solvent; by contrast pigments are insoluble or nearly so in all solvents. Because of their solubility, dyes can chemically bind to the material they color. Dye is generally applied in an aqueous solution and may require a mordant to improve the fastness of the dye on the fiber. The majority of natural dyes are derived from non-animal sources such as roots, berries, bark, leaves, wood, fungi and lichens.
LiquidState of matter The formation of a spherical droplet of liquid water minimizes the surface area, which is the natural result of surface tension in liquids.
Radioactive tracerA radioactive tracer, radiotracer, or radioactive label is a synthetic derivative of a natural compound in which one or more atoms have been replaced by a radionuclide (a radioactive atom). By virtue of its radioactive decay, it can be used to explore the mechanism of chemical reactions by tracing the path that the radioisotope follows from reactants to products. Radiolabeling or radiotracing is thus the radioactive form of isotopic labeling.*As an Amazon Associate I earn from qualifying purchases.