Pyramidal alkenes are alkene s in which the two carbon atom s making up the double bond are not coplanar with their four substituent s Ref . This deformation from a trigonal planar geometry to a tetrahedral molecular geometry is the result of angle strain induced in the molecule due to geometric constraints. Pyramidal alkenes only exist in the laboratory but are of interest because much can be learned from them about the nature of chemical bond ing. ref Chemistry of pyramidalized alkenes Santiago V zquez, and Pelayo Camps Tetrahedron Volume 61, Issue 22, 30 May 2005 , Pages 5147 5208 DOI 10.1016 j.tet.2005.03.055 ref In cycloheptene 1.1 the cis isomer is an ordinary unstrained molecule but the heptane ring is too small to accommodate a trans configured alkene group resulting in strain and twisting of the double bond. The p orbital misalignment is minimized by a degree of pyramidalization . In the related anti bredt molecule s it is not pyrimidalization but twisting that dominates. Image Cagealkenes.png center 300px Fig. 1 Pyramidal alkenes Pyramidalized cage alkenes also exist where symmetrical bending of the substituents predominates without p orbital misalignment. Image Anglestraindefinition.png center 400px Fig. 2 Angle definitions The pyramidalization angle math phi math b is defined as the angle between the plane defined by one of the doubly bonded carbons and its two substituents ... 10.1021 ol060994j ref isolation of a pyramidalalkene is not even possible in by Matrix Isolation matrix ... references Use dmy dates date September 2010 DEFAULTSORT PyramidalAlkene Category Alkenes ... ever M bius aromaticity M bius aromat . In one study ref A Highly Pyramidalized Cage Alkene Formed ... 10.1021 jo051488v Abstract ref the strained alkene 3.4 was synthesized with the highest pyramidalizion ... Alkene in a Homologous Series. Isolation and X ray Structure of the Product of the Ethanol Addition ... of ethylenebis triphenylphosphine platinum 0 does not give the intermediate alkene 4.2 but the platinum ... more details
because pyramidalization takes place See pyramidalalkene . cyclooctene trans Cyclooctene is a stable strained alkene and the orbital misalignment is only 19 with a dihedral angle of 137 normal 120 ... thumb right 120px A 3D model of ethylene , the simplest alkene. In organic chemistry , an alkene ... D. issue 8 9 ref The simplest alkene is ethylene C sub 2 sub H sub 4 sub , which has the International ... and hydroxylation . File Ear.png 400px alt Electrophilic addition Electrophilic addition of X Y to an alkene ... of a double bond in an unknown alkene. Oxymercuration Hydration reaction Hydration of alkenes ... alkene monomer s are referred to in a general way as polyolefin s or in rare instances as polyalkenes ... nickel 0 , a metal alkene complex Alkenes can be ligand s in metal complex es. The two carbon centres ... itself is used as a ligand, for example, in Zeise s salt . In addition, metal alkene complexes ... to produce a corresponding alkene. ref name Wade This is the reverse of the catalytic hydrogenation ... the alkene at high temperatures by entropy the T S portion of the equation Gibbs free energy Free ... methods for alkene synthesis in the laboratory is the elimination reaction elimination ... known. The E2 mechanism provides a more reliable elimination method than E1 for most alkene ... s rule Saytseff alkene is usually the major product. Alkenes are generated from halo sulfone s in the Ramberg ... compounds Another important method for alkene synthesis involves construction of a new carbon ... an alkene and Triphenylphosphine oxide Ph sub 3 sub P O . The Wittig reagent is itself prepared ... together with reduction to generate an alkene. Symmetrical alkenes can be prepared from a single aldehyde ... be used. A single ketone can also be converted to the corresponding alkene via its tosylhydrazone ... hydrovinylation is another important alkene synthesis process starting from alkene itself. ref name ... synthesis of disubstituted alkenes. If the cis alkene is desired, hydrogenation in the presence of Lindlar ... more details
enzyme Name alkene monooxygenase EC number 1.14.13.69 CAS number IUBMB EC number 1 14 13 69 GO code 0018645 image width caption In enzymology , an alkene monooxygenase EC number 1.14.13.69 is an enzyme that catalysis catalyzes the chemical reaction propene NADH H sup sup O sub 2 sub math rightleftharpoons math 1,2 epoxypropane NAD sup sup H sub 2 sub O The 4 substrate biochemistry substrates of this enzyme are propene , nicotinamide adenine dinucleotide NADH , hydrogen ion H sup sup , and oxygen O sub 2 sub , whereas its 3 product chemistry products are 1,2 epoxypropane , nicotinamide adenine dinucleotide NAD sup sup , and water H sub 2 sub O . This enzyme belongs to the family of oxidoreductase s, specifically those acting on paired donors, with O2 as oxidant and incorporation or reduction of oxygen. The oxygen incorporated need not be derived from O2 with NADH or NADPH as one donor, and incorporation of one atom o oxygen into the other donor. The systematic name of this enzyme class is alkene,NADH oxygen oxidoreductase . This enzyme is also called alkene epoxygenase . This enzyme participates in tetrachloroethene degradation . References reflist 1 cite journal author Small FJ, Ensign SA date 1997 title Alkene monooxygenase from Xanthobacter strain Py2. Purification and characterization of a four component system central to the bacterial metabolism of aliphatic alkenes journal J. Biol. Chem. volume 272 pages 24913&ndash 20 pmid 9312093 doi 10.1074 jbc.272.40.24913 issue 40 cite journal author Zhou NY, Jenkins A, Chan Kwo Chion CK, Leak DJ date 1999 title The alkene monooxygenase from Xanthobacter strain Py2 is closely related to aromatic monooxygenases and catalyzes aromatic monohydroxylation of benzene, toluene, and phenol journal Appl. Environ. Microbiol. volume 65 pages 1589&ndash 95 pmid 10103255 issue 4 pmc 91225 cite journal author Gallagher SC, Cammack R, Dalton H date 1997 title Alkene monooxygenase from Nocardia corallina B 276 is a member of the class of dinuclear ... more details
A pyramidal number is a figurate number that represents a pyramid with a base and a given number of sides. The term is most often used to refer to square pyramidal number s, which have four sides, but it can also refer to Tetrahedral number Triangular pyramidal number three sides Square pyramidal number four sides Pentagonal pyramidal number five sides Hexagonal pyramidal number six sides Heptagonal pyramidal number seven sides The formula for a r gonal pyramid number is math X frac n 2 2 n 3 left frac r 6 frac 1 3 right n left frac r 5 6 right math disambig Category Figurate numbers ar da Pyramidetal eo Piramida nombro fr Nombre pyramidal is P ram datala it Numero piramidale la Numerus pyramidalis nl Piramidegetal pl Liczby piramidalne pt N mero piramidal ... more details
Infobox neuron neuron name Pyramidal cell image neuron GolgiStainedPyramidalCell.jpg caption neuron A human neocortical pyramidal neuron stained via Golgi s method Golgi technique . Notice the apical dendrite ... projection neuron neurotransmitter Glutamate , GABA morphology Multipolar Pyramidal GraySubject 183 GrayPage 722 NeuroLex Pyramidal Cell NeuroLexID sao862606388 Pyramidal neurons pyramidal cells are a type ... . Pyramidal neurons are the primary excitation units of the mammalian prefrontal cortex and the corticospinal tract . Pyramidal neurons were first discovered and studied by Santiago Ram n ... into the pyramidal neuron and prefrontal function journal Cereb. Cortex volume 13 issue 11 pages ... P, Garc a Mar n V, Freire M title Three dimensional reconstruction and quantitative study of a pyramidal ... on pyramidal neurons have focused on topics ranging from neuroplasticity to cognition . Structure gallery Image GFPneuron.png Pyramidal neuron visualized by Green fluorescent protein gfp Image Hippocampal pyramidal cell.png A Hippocampal Pyramidal Cell gallery Features One of the main structural features of the pyramidal neuron is the triangular shaped soma biology soma , or cell body, after which the neuron is named. Other key structural features of the pyramidal cell are a single axon , a large ... of inhibitory and excitatory synapses on hippocampal CA1 pyramidal cells journal Neuroscience volume ... Dendrite The apical dendrites arise from the apex of the pyramidal cell s soma. The apical dendrite ... name Megias Basal Dendrite The basal dendrites arise from the base of the pyramidal cell s soma. The basal ..., the basal dendrites branch profusely. ref name Megias Pyramidal cells are among the largest neurons in the brain. Both in humans and rodents, pyramidal cell bodies somas average around 20 m. Pyramidal ... length of a pyramidal cell may reach several centimeters. The pyramidal cell s axon is often even ... spines receive most of the excitatory impulses EPSP s that enter a pyramidal cell. Dendritic spines ... more details
Refimprove date June 2007 Infobox Anatomy Name Pyramidal eminence Latin eminentia pyramidalis GraySubject 230 GrayPage 1042 Image Gray914.png Caption The medial wall and part of the posterior and anterior walls of the right tympanic cavity, lateral view. Pyramidal eminence labeled at left, second from bottom. Image2 Caption2 System Precursor MeshName MeshNumber DorlandsPre e 06 DorlandsSuf 12328455 The pyramidal eminence pyramid is situated immediately behind the fenestra vestibuli , and in front of the vertical portion of the facial canal it is hollow, and contains the Stapedius muscle its summit projects forward toward the fenestra vestibuli, and is pierced by a small aperture which transmits the tendon of the muscle. The cavity in the pyramidal eminence is prolonged downward and backward in front of the facial canal, and communicates with it by a minute aperture which transmits a twig from the facial nerve to the Stapedius muscle. Gray s Auditory and vestibular anatomy Category Auditory system anatomy stub ... more details
taxobox name Pyramidal Orchid image AnacamptisPyramidalis.jpg regnum Plantae unranked divisio Angiosperms unranked classis Monocots ordo Asparagales familia Orchidaceae subfamilia Orchidoideae genus Anacamptis species A. pyramidalis binomial Anacamptis pyramidalis binomial authority Carolus Linnaeus L. Louis Claude Richard Rich. synonyms Anacamptis condensata small Koch small Orchis appendiculata small Stokes small Orchis bicornis small Gilib. small Orchis condensata small Desf. small The Pyramidal Orchid , Anacamptis pyramidalis , is an herbaceous perennial plant belonging to the Genus Anacamptis of the family Orchidaceae . The scientific name Anacamptis derives from Greek anakamptein meaning bend forward , while the Latin name pyramidalis refers to the pyramidal form of the inflorescence . Description File Fertilisation of Orchids figure 4.jpg thumb 170px left Charles Darwin s book Fertilisation of Orchids included an illustration of the head of a moth with its proboscis laden with several pairs of Pollinium pollinia from Orchis pyramidalis This hardy plant reaches on average convert 10 25 cm of height, with a maximum of convert 60 cm . The stem is erect and unbranched. The basal leaves are linear lanceolate with parallel venation, up to convert 25 cm long, the cauline ... in a compact pyramidal shape is very distinctive and gives the orchid its common name. The colour ... pyramidalis var. tanayensis small Chenevard So in Keller small &ndash Tanay Pyramidal Orchid Flowers ... var. urvilleana small Sommier & Caruana Kreutz small &ndash Maltese Pyramidal Orchid Malta . Anacamptis pyramidalis var. sanguinea small Druce Kreutz small &ndash Western Irish Pyramidal Orchid. Inflorescence ... can be found anywhere in the Pyramidal Orchid s range its flowers are white. Medicinal Uses The dried ... for children and convalescents. Culture The Pyramidal Orchid was voted the County flowers of the United ... Hundswurz et P ramiid koerak pp es Anacamptis pyramidalis fr Orchis pyramidal hsb Pyramidowa w tromudka ... more details
Image Zermatt and Matterhorn.jpg thumb The Matterhorn , a classic peak A pyramidal peak , or sometimes in its most extreme form called a glacial horn , is a mountain top that has been modified by the action of ice during glaciation and frost weathering . If the use is unambiguous within a mountain context, then the simple terms peak or horn may be used. Formation Ice fields at the head of glacier s develop bowl shaped depression geology basins in the sides of a mountain called cirque s sometimes called corries or cwms . Cirque glaciers have specific characteristics. They have rotational sliding that abrades the floor of the basin but not the edge and that causes the bowl shape to form and also contributes to the development of the glacial moraine morainal or rock thresholds that separate them from downvalley slopes as well as hold in glacial lake s called tarns. As cirques are formed by glaciation in an alpine environment, the headwall and ridges known as ar te s become more steep and defined. This occurs due to Weathering Frost weathering freeze thaw and mass wasting beneath the ice surface. It is widely held that a common cause for headwall steepening and extension headward is the crevasse s known as bergschrund that occur between the moving ice and the headwall. This is a location where plucking and shattering has been seen by observers that explore the crevasses. A completed cirque is exposed as the glacier that was in the cirque melts away, after the periods of glaciation in the Pleistocene . When there are three or more of these cirque headwalls and ar tes joined together to form a single peak it creates a pyramid shape with very steep walls and it is called a horn or glacial horn. They are a common shape for mountain tops in well glaciated areas. The number of faces ... glaciers arete.html The Geography Site Aretes and Pyramidal Peaks http pubs.usgs.gov of 2004 1216 text.html ... fr Pic pyramidal hi it Picco piramidale ka ja pl Karling sl Topografski vrh ... more details
A hexagonal pyramidal number is a number formed by adding the first few hexagonal numbers . The first few numbers are 1, 7, 22, 50, 95, 161, 252, 372, 525, 715, 946, 1222, 1547, 1925 OEIS id A002412 The numbers have the form math n n 1 4n 1 over6 math References http mathworld.wolfram.com HexagonalPyramidalNumber.html Hexagonal pyramidal number at MathWorld numtheory stub Category Figurate numbers fr Nombre pyramidal hexagonal it Numero piramidale esagonale ta ... more details
A pentagonal pyramidal number is a figurate number that represents the number of objects in a pyramid with a pentagonal base. ref name MathWorld MathWorld title Pentagonal Pyramidal Number urlname PentagonalPyramidalNumber ref The n sup th sup pentagonal pyramidal number is equal to the sum of the first n pentagonal number s. The first few pentagonal pyramidal numbers are 1 number 1 , 6 number 6 , 18 number 18 , 40 number 40 , 75 number 75 , 126 number 126 , 196 number 196 , 288, 405, 550, 726, 936, 1183, 1470, 1800, 2176, 2601, 3078, 3610, 4200, 4851, 5566, 6348, 7200, 8125, 9126 OEIS id A002411 . The formula for the n sup th sup pentagonal pyramidal number is ref name OEIS oeis A002411 ref math frac n 2 n 1 2 math so the n sup th sup pentagonal pyramidal number is the average of n sup 2 sup and n sup 3 sup . ref name OEIS The n sup th sup pentagonal pyramidal number is also n times the n sup th sup triangular number . The generating function for the pentagonal pyramidal numbers is ref name MathWorld math frac x 2x 1 x 1 4 . math See also Tetrahedral number Triangular pyramidal number Square pyramidal number References references Category Figurate numbers eo Kvinangula piramida nombro fr Nombre pyramidal pentagonal it Numero piramidale pentagonale ja ta zh ... more details
A heptagonal pyramidal number is the sum of the first few heptagonal number s. The heptagonal number for n can be calculated by adding up the heptagonal numbers for 1 to n , or by using the formula n n 1 5 n 2 6. The first few heptagonal pyramidal numbers are 1 number 1 , 8 number 8 , 26 number 26 , 60 number 60 , 115 number 115 , 196, 308, 456, 645, 880, 1166, 1508, 1911, 2380, 2920, 3536, 4233, 5016, 5890, 6860, 7931, 9108 OEIS id A002413 Num stub Category Figurate numbers eo Sepangula piramida nombro fr Nombre pyramidal heptagonal it Numero piramidale ettagonale ta ... more details
Image Square pyramidal 3D balls.png thumb left 200px Idealized structure of a compound with square pyramidal coordination geometry. Image Xenon oxytetrafluoride 3D vdW.png thumb right 200px Structure of xenon oxytetrafluoride , an example of a molecule with the square pyramidal coordination geometry. In molecular geometry , square based pyramidal geometry describes the shape of certain compounds with the formula ML sub 5 sub where L is a ligand . If the ligand atoms were connected, the resulting shape would be that of a pyramid with a square base. The geometry is common for certain main group compounds that have a stereochemically active lone pair, as described by VSEPR theory . Certain compounds crystallize in both the trigonal bipyramidal and the square pyramidal structures, notably Ni CN sub 5 sub sup 3 sup . ref cite journal last1 Spiro first1 Thomas G. last2 Terzis first2 Aristides last3 Raymond first3 Kenneth N. doi 10.1021 ic50093a006 title Structure of Ni CN sub 5 sub sup 3 sup . Raman, infrared, and x ray crystallographic evidence year 1970 pages 2415 volume 9 journal Inorg. Chem. issue 11 ref As a transition state in Berry Pseudorotation As a trigonal bipyramidal molecule undergoes Berry pseudorotation , it proceeds via an intermediary stage with the square planar geometry. Thus even though the geometry is rarely seen as the ground state, it is accessed by a low energy distortion from a trigonal bipyramid. Pseudorotation also occurs in square pyramidal molecules. Molecules ... used is similar to the Berry mechanism. Examples Some molecular compounds that adopt square pyramidal geometry are XeOF sub 4 sub , ref Square Pyramidal Molecular Geometry . VSEPR. http www.up.ac.za academic chem mol geom planpyr.htm ref and XF sub 5 sub X Cl, Br, I also have square pyramidal geometries. ref Square Pyramidal Geometry . http intro.chem.okstate.edu 1314F97 Chapter9 5BP1LP.html ref ... 0 13 035471 6. ref Complexes of vanadium IV , such as VO acac sub 2 sub are square pyramidal acac ... more details
Infobox molecular geometry Examples Image File Pentagonal pyramidal 3D balls.png Symmetry group Electron direction Atom direction Bond angle mu In chemistry , pentagonal pyramidal molecular geometry describes the shape of compounds where in six atoms or groups of atoms or ligand s are arranged around a central atom, defining the vertices of a pentagonal pyramid . It is one of the few Molecular geometry molecular geometries with uneven bond angle s. Image AX6E1 2D.png thumbnail 100px Examples XeOF sub 5 sub sup sup IOF sub 5 sub sup 2 sup References http mathworld.wolfram.com PentagonalPyramid.html MolecularGeometry DEFAULTSORT Pentagonal Pyramidal Molecular Geometry Category Molecular geometry es Geometr a molecular piramidal pentagonal nl Pentagonaal piramidale moleculaire geometrie ja ... more details
Infobox Bone Name Pyramidal process of palatine bone Latin processus pyramidalis ossis palatini GraySubject 41 GrayPage 168 Image Gray192.png Caption Medial wall of left orbit. Pyramidal process of palatine labeled at bottom right. Image2 Gray169.png Caption2 Left palatine bone. Posterior aspect. Enlarged. Pyramidal process labeled at bottom left. System Precursor MeshName MeshNumber DorlandsPre p 34 DorlandsSuf 12667617 The pyramidal process of the palatine bone projects backward and lateralward from the junction of the horizontal and vertical parts, and is received into the angular interval between the lower extremities of the pterygoid plate s. On its posterior surface is a smooth, grooved, triangular area, limited on either side by a rough articular furrow. The furrows articulate with the pterygoid plates, while the grooved intermediate area completes the lower part of the pterygoid fossa and gives origin to a few fibers of the Pterygoideus internus. The anterior part of the lateral surface is rough, for articulation with the tuberosity of the maxilla its posterior part consists of a smooth triangular area which appears, in the articulated skull, between the tuberosity of the maxilla and the lower part of the lateral pterygoid plate, and completes the lower part of the infratemporal fossa. On the base of the pyramidal process, close to its union with the horizontal part, are the lesser palatine foramina for the transmission of the posterior and middle palatine nerve s. Additional images gallery Image Gray187.png Base of skull. Inferior surface. gallery External links RocheLexicon 34257.000 1 Gray s Facial bones Category Bones of the head and neck musculoskeletal stub ro Procesul piramidal al osului palatin ... more details
pp semi indef Image Square pyramidal number.svg thumb 360px Geometric representation of the square pyramidal number nowrap 1 1 4 9 16 30. File Mus e historique de Strasbourg Boulets en pierre.jpg thumb A pyramid of cannonball s in the Mus e historique de Strasbourg . The number of balls in the pyramid can be calculated as the fifth square pyramidal number, 55. In mathematics , a pyramid number , or square pyramidal number , is a figurate number that represents the number of stacked spheres in a pyramid with a square base. Square pyramidal numbers also solve the problem of counting the number of squares in an n × n grid. Formula The first few square pyramidal numbers are 1 number 1 , 5 number 5 , 14 number 14 , 30 number 30 , 55 number 55 , 91 number 91 , 140 number 140 , 204 number 204 , 285, 385, 506, 650, 819 OEIS id A000330 . These numbers can be expressed in a formula as math P n sum k 1 nk 2 frac n n 1 2n 1 6 frac 2n 3 3n 2 n 6 . math This is a special case of Faulhaber s formula ... Relations to other figurate numbers The square pyramidal numbers can also be expressed as sums ... in this representation are tetrahedral number s, and this formula expresses a square pyramidal number .... Square pyramidal numbers are also related to tetrahedral numbers in a different way math P n frac14 binom 2n 2 3 . math The sum of two consecutive square pyramidal numbers is an octahedral ... square number and the 24th square pyramidal number. This fact was proven by G. N. Watson in 1918. Another ... diagonals with odd numbers, square numbers, and square pyramidal numbers, respectively, and generates ... way that the square pyramidal numbers can be defined as a sum of consecutive squares, the squared ... is given by the square pyramidal numbers. The number of rectangles in a square grid is given by the squared ... Pyramidal Number Category Figurate numbers Category Pyramids cs Pyramidov slo de Quadratische Pyramidalzahl es N mero piramidal cuadrado eo Kvadrata piramida nombro fr Nombre pyramidal carr it Numero ... more details
Image Phosphine 3D vdW.png thumb left 200px Phosphine , an example of a molecule with a trigonal pyramidal geometry. Infobox molecular geometry Image File Pyramidal 3D balls.png Symmetry group Cyclic symmetries C sub 3v sub Electron direction 4 Atom direction 3 Bond angle 107 mu Examples ammonia NH sub 3 sub , phosphorus trichloride PCl sub 3 sub In chemistry , a trigonal pyramid is a molecular geometry with one atom at the Apex geometry apex and three atoms at the corners of a trigonal base. When all three atoms at the corners are identical, the molecule belongs to Molecular symmetry point group C sub 3v sub . One example of a molecule with a trigonal pyramidal geometry is ammonia NH sub 3 sub . Some molecules and ions with trigonal pyramidal geometry include the xenon trioxide molecule, XeO sub 3 sub , the chlorate ion, ClO sub 3 sub sup sup , the sulfite ion, SO sub 3 sub sup 2 sup , and the phosphite ion, PO sub 3 sub sup 3 sup . In organic chemistry, molecules which have a trigonal pyramidal geometry are sometimes described as orbital hybridisation sp sup 3 sup hybridized . The AXE method for VSEPR theory states that the classification is AX sub 3 sub E. Citation needed date January 2008 Trigonal pyramidal geometry in ammonia The nitrogen molecule in ammonia has 5 valence electron s and bonds with three hydrogen atoms to complete the octet rule octet . This would result in the geometry of a regular tetrahedron with each bond angle inverse trigonometric function cos sup 1 sup 109.5 . However, the three hydrogen atoms are repelled by the electron lone pair in a way that the geometry is distorted to a trigonal pyramid regular 3 sided pyramid with bond angles of 107 . In contrast, boron trifluoride is flat, adopting a trigonal planar geometry because the boron does not have a lone pair of electrons. In ammonia the trigonal pyramid undergoes rapid nitrogen inversion . ref ... sv Trigonal pyramidal geometri ... more details
Infobox Anatomy Name Pyramid of thyroid Latin lobus pyramidalis glandulae thyroideae GraySubject 272 GrayPage 1269 Image Gray1174.png Caption The thyroid gland and its relations. Pyramid labeled at center left. Image2 Illu08 thyroid.jpg Caption2 Thyroid System Precursor MeshName MeshNumber The pyramidal lobe is the third Lobe anatomy lobe of conical shape frequently arises from the upper part of the isthmus, or from the adjacent portion of either lobe, but most commonly the left, and ascends as far as the hyoid bone . It is occasionally quite detached, or may be divided into two or more parts. External links SUNYAnatomyFigs 26 01 04 Gray s Endocrine system Category Endocrine system anatomy stub ... more details
morefootnotes date July 2011 In chemistry , the oxonium ion is any oxygen cation with three chemical bond bonds . ref JerryMarch ref The simplest oxonium ion is the hydronium ion H sub 3 sub O sup sup . Another oxonium ion frequently encountered in organic chemistry is obtained by protonation or alkylation of a carbonyl group e.g. R C O sup sup R which forms a resonance structure with the fully fledged carbocation R C sup sup O R and is therefore especially stable center Image Carbonyl oxonium resonance 2D skeletal.png 250px center Stable alkyl oxonium salts exist they are extensively used as alkylating agents. For example, triethyloxonium tetrafluoroborate Chem Et 3 O Chem BF 4 is a white crystalline solid. It is a powerful ethylating agent. It can be used, for example, to produce ethyl esters when the conditions of traditional Fischer esterification are unsuitable. center align center class wikitable center Image Oxonium ion 2D.png 100px center center Image Trimethyloxonium 2D skeletal.png 100px center center Image Trimethyloxonium 3D balls.png 100px center center Image Trimethyloxonium 3D vdW.png 100px center center general trigonal pyramidal molecular geometry pyramidal br oxonium ion center center skeletal formula of the br trimethyloxonium cation center center ball and stick model br of trimethyloxonium center center space filling model br of trimethyloxonium center center Other hydrocarbon oxonium ions are formed by protonation or alkylation of alcohol s or ethers Chem R C O R 1 R 2 . In acidic media, the oxonium functional group produced by protonating an alcohol can be a leaving group in the Elimination reaction E2 elimination reaction, because when it receives an electron, it becomes a water molecule. The product is an alkene . Extreme acidity, heat and dehydrating conditions are usually required. Oxatriquinane and oxatriquinacene are unusually stable oxonium ions, first described in 2008. Oxatriquinane does not react with boiling water or with alcohol s, ... more details
Image AX3E0 3D balls.png thumb left 200px Idealized structure of a compound with trigonal planar coordination geometry. Image Boron trifluoride 3D vdW.png thumb right 200px Structure of boron trifluoride , an example of a molecule with trigonal planar geometry. In chemistry , trigonal planar is a molecular geometry model with one atom at the center and three atoms at the corners of a triangle, called peripheral atoms, all in one plane. ref name March Jerry March Advanced Organic Chemistry 3rd Ed. ref In an ideal trigonal planar species, all three ligands are identical and all bond angles are 120 . Such species belong to the point group D sub 3h sub . Molecules where the three ligands are not identical, such as formaldehyde H sub 2 sub CO , deviate from this idealized geometry. Examples of molecule s with trigonal planar geometry include boron trifluoride BF sub 3 sub , formaldehyde H sub 2 sub CO , phosgene COCl sub 2 sub , and sulfur trioxide SO sub 3 sub . Some ions with trigonal planar geometry include nitrate NO sub 3 sub sup sup , carbonate ion CO sub 3 sub sup 2 sup , and guanidine guanidinium C NH sub 2 sub sub 3 sub sup sup . In organic chemistry, planar, three connected carbon centers that are trigonal planar are often described as having orbital hybridisation sp sup 2 sup hybridization . ref Holleman, A. F. Wiberg, E. Inorganic Chemistry Academic Press San Diego, 2001. ISBN 0 12 352651 5. ref ref G. L. Miessler and D. A. Tarr Inorganic Chemistry 3rd Ed, Pearson Prentice Hall publisher, ISBN 0 13 035471 6. ref Nitrogen inversion is the distortion of pyramidal amine s through a transition state that is trigonal planar. Pyramidalization is a distortion of this molecular shape towards a tetrahedral molecular geometry . One way to observe this distortion is in pyramidal alkene s. ref name March See also AXE method Molecular geometry VSEPR theory References references External links http www.3dchem.com 3D Chem Chemistry, Structures, and 3D Molecules http www.ium ... more details
McMurry can refer to McMurry University in Abilene, Texas The McMurry reaction , in which two carbonyls are coupled to give a single alkene John E. McMurry , whose name is given to the McMurry reaction disambig ... more details
A pregnene is an alkene derivative of a pregnane . ref MeshName Pregnenes ref An example is cortisone . gallery Image Cortison.svg Cortisone Image Ethisterone.png Ethisterone Image Spironolactone.svg Spironolactone gallery References Reflist See also Pregnanes Category Glucocorticoids Chemistry stub ... more details
Pyramidalis , pyramidal in Latin, may refer to Pyramidalis muscle , a small and triangular muscle, anterior to the Rectus abdominis, and contained in the rectus sheath in human anatomy Pyramidalis nasi , a small pyramidal slip of muscle deep to the superior orbital nerve, artery and vein Ulmus procera Pyramidalis , an English elm cultivar a rosemary cultivar SpeciesAbbreviation pyramidalis Disambiguation ... more details
Unreferenced date December 2009 Image Enyne.png thumb right The structure of a typical enyne group. An enyne is a functional group in organic chemistry consisting of a conjugated system conjugated alkyne and alkene group. See also Enyne metathesis Category Functional groups fr nyne nl Eenyn ... more details
distinguish hexane Unreferenced stub auto yes date December 2009 Hexene is a higher olefin , or alkene with a formula Carbon C sub 6 sub Hydrogen H sub 12 sub . The Hex is derived from the fact that there are 6 carbon atoms in the molecule, while the ene suffix denotes that two carbon atoms are connected via a double bond. There are several isomer s of hexene, depending on the position of the double bond and the branching of the carbon chain. One of the most common industrially useful isomers is 1 Hexene 1 hexene , an alpha olefin . Hexene is used as a comonomer in the production of polythene . See also Alkene ene Alkenes Category Alkenes Hydrocarbon stub ar cs Hexen de Hexene fi Hekseeni it Esene nl Hexeen sv Hexen alken ... more details
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