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Concept in organic chemistry
In organic chemistry, hyperconjugation (σ-conjugation or no-bond resonance) refers to the delocalization of electrons with the participation of bonds of
Hyperconjugation
Phenomenon in organic chemistry
In organic chemistry, negative hyperconjugation is the donation of electron density from a filled π- or p-orbital to a neighboring σ*-orbital. This phenomenon
Negative_hyperconjugation
Rule for predicting outcomes of some addition reactions
substituted the carbocation, the more stable it is, due to induction and hyperconjugation. The major product of the addition reaction will be the one formed
Markovnikov's_rule
Organic compound (H3C–CH3)
is perhaps the strongest candidate, with the stabilizing effect of hyperconjugation on the staggered conformation contributing to the phenomenon. Theoretical
Ethane
Special type of hyperconjugation
Negative hyperconjugation is a theorized phenomenon in organosilicon compounds, in which hyperconjugation stabilizes or destabilizes certain accumulations
Negative hyperconjugation in silicon
Negative_hyperconjugation_in_silicon
Molecular-structural phenomenon
are two main explanations for the gauche effect: hyperconjugation and bent bonds. In the hyperconjugation model, the donation of electron density from the
Gauche_effect
Tendency of some substituents on a cyclohexane ring to prefer axial orientation
widely accepted explanation is that there is a stabilizing interaction (hyperconjugation) between the unshared electron pair on the endocyclic heteroatom (within
Anomeric_effect
Covalent bond between carbon and fluorine atoms
are two main explanations for the gauche effect: hyperconjugation and bent bonds. In the hyperconjugation model, the donation of electron density from the
Carbon–fluorine_bond
Bond arrangement in organic chemistry
syn-periplanar. The parallel orbitals can overlap and become involved in hyperconjugation. If the bonding orbital is an electron donor and the anti-bonding orbital
Anti-periplanar
Various molecular structures formed only by rotation about single bonds
interactions of the substituents as well as orbital interactions such as hyperconjugation are responsible for the relative stability of conformers and their
Rotamer
System of connected p-orbitals with delocalized electrons in a molecule
p orbital. Hyperconjugation is commonly invoked to explain the stability of alkyl substituted radicals and carbocations. Hyperconjugation is less important
Conjugated_system
Atom, molecule, or ion that has an unpaired valence electron; typically highly reactive
−NR); to conjugated π bonds in alkenes, carbonyls, or nitriles; or in hyperconjugation to nearby hydrogen- or fluorine-rich moieties. Many of the above functional
Radical_(chemistry)
Compound derived from an acid
rather than the S-trans (or E) alternative, due to a combination of hyperconjugation and dipole minimization effects. The preference for the Z conformation
Ester
Organic cation
that the reaction proceeds through a vinyl cation transition state. Hyperconjugation and hydrogen bonding was evoked to explain the accessibility of the
Vinyl_cation
Permanent bond dipole due to electron-rich or -poor groups in a molecule
misunderstanding. Due to early experimentation, before an understanding of hyperconjugation, results such as the more rapid nitration of toluene compared to benzene
Inductive_effect
Antioxidant
the phenolic hydroxyl moiety through the inductive effect and the hyperconjugation effect, reduce the bond dissociation energy of the phenolic hydroxyl
Butylated_hydroxytoluene
Ion with a positively charged carbon atom
neighboring C–H or C–C bonds into the "empty" p orbital, known as hyperconjugation, is still an important stabilizing factor, and these bonds have a tendency
Carbocation
Description of a molecule's true bond structure as a combination of structures
well-studied example of delocalization that does not involve π electrons (hyperconjugation) can be observed in the non-classical 2-Norbornyl cation Another example
Resonance_(chemistry)
Anomaly in chemical reactivity of certain organic molecules
terms of a conjugation effect and in later years after the advent of hyperconjugation (1939) as its predecessor. A fundamental problem with the effect is
Baker–Nathan_effect
Predictive model in organic chemistry
of mixing full and empty orbitals to delocalize electrons, known as hyperconjugation. When the highest occupied molecular orbital (HOMO) of one system and
Cieplak_effect
Electron-deficient chemical bond where three atoms share two electrons
also occurs in carbon compounds, where it is sometimes referred to as hyperconjugation- another name for asymmetrical three-center two-electron bonds. The
Three-center two-electron bond
Three-center_two-electron_bond
Chemical rearrangement
promote fragmentation by stabilizing carbocation formation through hyperconjugation. As shown in the above picture, the "stable" carbocation is formed
Beckmann_rearrangement
Radicals centered on boron atoms
lewis base donates a lot of electron density to the boryl radical via hyperconjugation, this manifests itself as an interaction which favors the trigonal
Boryl_radicals
Empirical rule in organic chemistry
separation between alkyl groups is greatest in the most substituted alkene. Hyperconjugation, which describes the stabilizing interaction between the HOMO of the
Zaytsev's_rule
Indian academic examination
hydrogen bonding, inductive effects, isomerism, resonance, aromaticity, hyperconjugation, mesomerism, carbocations and carbanions, bond cleavage including heterolysis
Joint Entrance Examination – Advanced
Joint_Entrance_Examination_–_Advanced
Class of ions
superacid media. The stabilization by alkyl groups is explained by hyperconjugation. The donation of electron density from a β C-H or C-C bond into the
Carbenium_ion
Chemical compound
show that 1,2-difluoroethane prefers the gauche conformation due to hyperconjugation effects. Since F is much more electronegative than the C atom, it will
1,2-Difluoroethane
Class of chemical reactions
overall activation energy. The lowering of the LUMO is the result of hyperconjugation between alkyne π donor orbitals and CF σ* acceptors. These interactions
Bioorthogonal_chemistry
of the non-bonding orbital at phosphorus through n(P) → σ*(Si-Si) hyperconjugation is more effective after metalation. This is due to the higher negative
Phosphasilene
Chemical reactions involving organic compounds
determine the stability of reactants and products such as conjugation, hyperconjugation and aromaticity and the presence and stability of reactive intermediates
Organic_reaction
Chemical reagent used to differentiate 1°, 2°, 3° Alcohols
carbocations, and primary carbocations are the least stable(due to hyperconjugation). An equimolar mixture of ZnCl2 and concentrated HCl is the reagent
Lucas'_reagent
Molecular form in which substituents on two adjacent atoms are closest together
explained by steric hindrance, but its origins sometimes actually lie in hyperconjugation (as when the eclipsing interaction is of two hydrogen atoms). In the
Eclipsed_conformation
Organic anion formed by deprotonating a carbonyl (>C=O) compound
deprotonation. Substitution improves alkene thermodynamics through additional hyperconjugation, but hinders initial proton loss. In the methylcyclohexanone example
Enolate
to the LUMO of the d0 of the metal center which is analogous to the hyperconjugation effect (see figure on the right), thus increasing the stability of
Β-Carbon_elimination
Substitution reaction with a carbocation intermediate
carbocation is also stabilized by both inductive stabilization and hyperconjugation from attached alkyl groups. The Hammond–Leffler postulate suggests
SN1_reaction
Equation in physical chemistry
for F but sensible values for R. This is most commonly explained by hyperconjugation, meaning little to no inductive effects but partial resonance effects
Swain–Lupton_equation
an anti-periplanar geometry with O-5. This orientation allows for hyperconjugation of O-5 to O-4 and O-6, removing electron density from O-5. The loss
Armed and disarmed saccharides
Armed_and_disarmed_saccharides
Model to predict the geometry of molecules
softness-hardness-based models, aromaticity and antiaromaticity, hyperconjugation, etc. The application to main-group element compounds utilizes principles
Second-order Jahn-Teller distortion in main-group element compounds
Second-order_Jahn-Teller_distortion_in_main-group_element_compounds
Breaking a molecular bond such that both fragments retain an electron
in other words, electron delocalization. Hyperconjugation Carbon radicals are stabilized by hyperconjugation, meaning that more substituted carbons are
Homolysis_(chemistry)
Chemical reaction
methyl groups increase the electron density of the double bond by hyperconjugation): ethylene (1, no methyl groups), propene (24, one methyl group), cis-2-butene
Prilezhaev_reaction
Organometallic compound containing carbon–silicon bonds
organyl analogues. When geometry allows, silicon exhibits negative hyperconjugation, reversing the usual polarization on neighboring atoms.[citation needed]
Organosilicon_chemistry
Influences on a molecule's properties not due to bonds or geometry
Resonance electron-withdrawing groups are classed as deactivating. Hyperconjugation is the stabilizing interaction that results from the interaction of
Electronic_effect
Chemical structure derived from cyclopropane
description of C=C double bonds. Cyclopropyl groups are good donors in hyperconjugation resulting in a considerable stabilization of carbocations. In contrast
Cyclopropyl_group
Organic ion with a negatively charged carbon atom
neopentyl and phenethyl anions are also bound, as a result of negative hyperconjugation of the lone pair with the β-substituent (nC → σ*C–C). The same holds
Carbanion
electron-releasing and can stabilize a positive charge in the β position through hyperconjugation. Electrophilic additions to allyl- and vinylsilanes take advantage
Electrophilic substitution of unsaturated silanes
Electrophilic_substitution_of_unsaturated_silanes
Aspect of quantum chemistry
bromide can be expressed as nO → σ*C–Br, and stabilization of alkenes by hyperconjugation by neighboring C–H bonds on alkyl groups is symbolically expressed
Localized_molecular_orbitals
by the extended pi bond network (formation of anion). Furthermore hyperconjugation caused by the extended network draws electrons from the bond to be
Dunathan stereoelectronic hypothesis
Dunathan_stereoelectronic_hypothesis
Organic compounds with the structure O=P(OR)3
significant role in bonding. Current models rely on either negative hyperconjugation, or a more complex arrangement with a dative-type bond from P to O
Organophosphate
Affect on molecular properties due to spatial arrangement of electron orbitals
These include important phenomena such as the anomeric effect and hyperconjugation. Stereoelectronic effects should not be misunderstood as a simple combination
Stereoelectronic_effect
surrounding sp3 hybridized carbons can stabilize the carbocation through hyperconjugation. This occurs when adjacent sp3 orbitals have a weak overlap with the
Tertiary_carbon
Study of compounds with carbon to zinc bonds
trimethylsilylmethyl- (Me3SiCH2-), which is stabilized through negative hyperconjugation in silicon and does not transfer: R 2 Zn + ( TMSM ) 2 Zn ↽ − ⇀ THF
Organozinc_chemistry
American Professor of Chemistry
are now recognized as a weak form of resonance-type delocalization (hyperconjugation) that is ubiquitous in saturated molecules. With Alan E. Reed and Larry
Frank_A._Weinhold
Type of compound
phosphinidenes have triplet ground states, possibly in-part due to a negative hyperconjugation. Substituents containing lone pairs (e.g. -NX2, -OX, -PX2 ,-SX) stabilize
Phosphinidene
Covalent chemical bond between silicon and oxygen atoms
angles smaller than Si–O–Si but larger than C–O–C. The main reasons are hyperconjugation (donation from an oxygen p orbital to an Si–R σ* sigma antibonding
Silicon–oxygen_bond
Method of identifying trace chemicals
such as the electron octet rule, the resonance stabilization and hyperconjugation and so on. The Rule of 13 is a simple procedure for tabulating possible
Mass_spectral_interpretation
American chemist (1893–1978)
of these reactions supported the later development of the theory of hyperconjugation. Conant's investigations helped in the development of a more comprehensive
James_B._Conant
Pericyclic chemical reaction
dirhodium(II)tetracarboxylate metallocarbene stabilized by πC-Rh→πC=O hyperconjugation.). In this situation, the metal ligands will influence the regioselectivity
1,3-Dipolar_cycloaddition
Chemical compound
The rest (~15%) of the bond strength may be attributed to a negative hyperconjugation interaction: the N lone pairs can donate some electron density into
Hexachlorophosphazene
American astronomer, computational chemist and mathematics educator
intensities" (Reports on Progress in Physics 1940, with Mulliken), "Hyperconjugation" (Journal of the American Chemical Society 1941, with Mulliken and
Carol_Jane_Anger_Rieke
Organic reaction in which a pi bond and sigma bond are interconverted
reaction rate for the trimethylsilyl compound can be explained by silicon hyperconjugation as the βC-Si bond weakens the cyclobutane C-C bond by donating electrons
Electrocyclic_reaction
Chemical reaction
by the silicon substituent ("β-silicon effect", a form of silicon-hyperconjugation). Sakurai, Hideki; Hosomi, Akira; Kumada, Makoto (1969). "Addition
Sakurai_reaction
hypervalent molecules. The dominance of ionic bonding and negative hyperconjugation over d-orbital participation". Journal of the American Chemical Society
Covalent_radius_of_fluorine
Change in chemical reaction rate due to isotopic substitution
from sp3 to sp2 or vice versa (an α SKIE), or bond weakening due to hyperconjugation in cases where a carbocation is being generated one carbon atom away
Kinetic_isotope_effect
silicon are hindered by the partial π bond formed through negative hyperconjugation. The process proceeds with alkenes and alkynes, possibly through [2+2]
Transition metal silyl complexes
Transition_metal_silyl_complexes
cyanide Hydrogen peroxide Hydrogen sulfide Hydrolysis Hydroxide Hydroxyl Hyperconjugation Ice Idocrase Illite Ilmenite Ilya Prigogine Indium Infrared spectroscopy
Index_of_chemistry_articles
bond and stabilization of the phosphorus can be justified by negative hyperconjugation, in which electron density on the nitrogen p-orbital delocalizes into
Iminophosphorane
1977. ISBN 0-471-11671-8, ISBN 978-0-471-11671-4. The Question of Hyperconjugation or of Bulk Effect in the Beckmann Rearrangement D.E. Pearson, J.D Bruton
Donald_E._Pearson
Indian computational chemist and former professor
his studies have reportedly widened the understanding of negative hyperconjugation in organic, organometallic and inorganic systems and captodative stabilization
Jayaraman_Chandrasekhar
Chemical compound
tris(dimethylamino)sulfonium trifluoromethoxide. Evidence for negative fluorine hyperconjugation". Journal of the American Chemical Society. 107 (15): 4565–4567. doi:10
Trifluoromethanol
Sub-field of organic chemistry
reason why the hydroxyl group at OH-4 in pyranosides is unreactive. Hyperconjugation is involved when OH-4 is anti-periplanar to the ring oxygen, which
Carbohydrate_synthesis
British scientist (1935–2022)
"Tributes paid to Dr Andrew McLachlan". McLachlan, A.D. (1958). "Hyperconjugation in the electron resonance spectra of free radicals". Molecular Physics
Andrew_David_McLachlan
Chemical compound
cyclopropane EAG activates the aliphatic C–H bonds adjacent to it via hyperconjugation (oxygen and nitrogen heteroatoms can also do this). The bonds highlighted
White–Chen_catalyst
Chemical compound
bond angle in disiloxane has been attributed primarily to negative hyperconjugation between oxygen p orbitals and silicon–carbon σ* antibonding orbitals
Disiloxane
English physicist
(1999). "The Whiffen effect of symmetry-enhanced and symmetry-forbidden hyperconjugation in spin-paired molecules". Journal of the Chemical Society, Perkin
David_Whiffen
Concept in linear algebra
^{\otimes 4}\otimes \mathbb {H} \simeq \mathbb {H} ^{\otimes 5}} . A hyperconjugation is defined by ( H ⊗ m ) ∗ = ( H c ⊗ m ) = H c ⊗ H c ⊗ ⋯ ⊗ H c {\displaystyle
Quaternionic_matrix
tolerated. The nucleophilicity increases Si < Ge < Sn as well as the hyperconjugation effect known as the β-silicon effect Si < Ge << Sn. The Si–C bond is
Organogermanium compounds in cross-coupling reactions
Organogermanium_compounds_in_cross-coupling_reactions
HYPERCONJUGATION
HYPERCONJUGATION
HYPERCONJUGATION
HYPERCONJUGATION
Girl/Female
Australian, French, Latin
Similar to Dominic; God Given; Gift of God
Girl/Female
Hindu
Dispeller of all distresses
Surname or Lastname
English
English : variant of Donat.Possibly a respelling of French Donné, also a variant of Donat.
Boy/Male
French
Blond ruler.
Boy/Male
Arabic, Muslim
Luckiest of the Age
Boy/Male
English
From the east cottage.
Girl/Female
Tamil
Desire
Boy/Male
Gujarati, Hindu, Indian, Kannada, Traditional
Lord Shiva's Son
Boy/Male
English Scottish Shakespearean
Lives by the winding stream.
Boy/Male
Indian, Sanskrit
Couple; Zodiac Sign Gemini
HYPERCONJUGATION
HYPERCONJUGATION
HYPERCONJUGATION
HYPERCONJUGATION
HYPERCONJUGATION