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Topic: Radical substitution

Related Topics

Elimination reaction

Electrophilic substitution

Electrophilic aromatic substitution

Organic reaction

Reduction reaction

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	Substitution reaction - Wikipedia, the free encyclopedia
		Organic substitution reactions are classified in several main organic reaction types depending on whether the reagent that brings about the substitution is considered an electrophile or a nucleophile, whether a reactive intermediate involved in the reaction is a carbocation, a carbanion or a free radical or whether the substrate is aliphatic or aromatic.
		A nucleophile reacts with an aliphatic substrate in a nucleophilic aliphatic Substitution reaction.
		Electrophiles are involved in electrophilic substitution reactions and particularly in electrophilic aromatic substitutions.
	en.wikipedia.org /wiki/Substitution_reaction (215 words)

	Radical (chemistry) - Wikipedia, the free encyclopedia
		In the upper atmosphere free radicals are produced through dissociation of the source molecules, particularly the normally unreactive chlorofluorocarbons by solar ultraviolet radiation or by reactions with other stratospheric constituents.
		Free radicals play an important role in a number of biological processes, some of which are necessary for life, such as the intracellular killing of bacteria by neutrophil granulocytes.
		Because free radicals are necessary for life, the body has a number of mechanisms to minimize free radical induced damage and to repair damage which does occur, such as the enzymes superoxide dismutase, catalase, glutathione peroxidase and glutathione reductase.
	en.wikipedia.org /wiki/Radical_(chemistry) (2089 words)

	Radical Reaction Chemistry
		One radical coupling and homolytic bond fission process is commonly encountered while studying thermodynamics and equilibrium theory, although the radical fragmentation nature of the reaction is usually not discussed.
		The triphenylmethyl radical adopts a propeller-like conformation, it is non-planar due to steric hindrance imposed by the bulky phenyl ligands.
		The peroxide radical is able to abstract a hydrogen from a neighbouring hydrocarbon to form the hydroperoxide and another radical centre which propagates the chain reaction.
	www.meta-synthesis.com /webbook/14_radical/radical.html (1170 words)

	Non-ionic Chemical Reactions
		For example, the esr signal from methyl radicals, generated by x-radiation of solid methyl iodide at -200º C, is a 1:3:3:1 quartet (predicted by the n + 1 rule).
		If a radical transfer reagent, such as an alkyl halide or xanthate, is not present in excess, an alkene derived radical may exist long enough to add to other alkene molecules in a repetitive fashion, leading to a polymeric product, as shown here.
		A pair of radicals is generated by photohomolysis of the weak N–O bond of a nitrite ester.
	www.cem.msu.edu /~reusch/VirtualText/nonionic.htm (4001 words)

	What is free radical substitution?
		A simple example of substitution is the reaction between methane and chlorine in the presence of UV light (or sunlight).
		Free radicals are atoms or groups of atoms which have a single unpaired electron.
		A free radical substitution reaction is one involving these radicals.
	www.chemguide.co.uk /mechanisms/freerad/whatis.html (411 words)

	Free Radical Reactions
		(The term "free radical" or "radical" is used to mean an atom or group in which one of the bonding orbitals is occupied by a single electron.
		In this instance the intermediates are free radicals and the secondary free radical is formed faster than the primary free radical.
		The product of that reaction would also be a free radical and could add to another molecule of ethylene, etc. The outcome is that the each reaction extends the growing chain by two carbons and produces a free radical intermediate at the end of the chain which can continue the reaction.
	chemistry2.csudh.edu /rpendarvis/Radicals.html (1620 words)

	[No title]
		Note that substitution patterns of alkenes may be indicated by certain low frequency absorptions 13.3B Begin to learn the characteristic IR absorption frequencies of common functional groups, such as various carbonyl-containing groups, hydroxyl groups, and amines (also see Table 13.2).
		Regarding the relative stability of substituted arenium ions, be able to explain the stabilizing effect of electron releasing substituents and the destabilizing effect of electron withdrawing substituents by inductive and/or resonance explanations.
		Be able to explain the orientation of substitution (meta) on a benzene ring with an electron withdrawing substituent using arguments of relative electron density in the various potential arenium ion intermediates.
	www.chem.plu.edu /organic/334ss_97.htm (10802 words)

	ALKYL HALIDES (Site not responding. Last check: 2007-11-03)
		A radical chain mechanism is one in which a particular set or two or three steps is repeated over and over without the necessity of generating more radicals.
		However, since the radical concentrations are extremely small, the probability of one radical meeting another is much less than for a radical to meet a molecule of chlorine or methane.
		The strong resonance stabilization of the allyl radical is the reason that the D for the allylic hydrogens of propene and other allylic hydrogens is much smaller than for typical hydrogens attached to carbon.
	research.cm.utexas.edu /nbauld/teach/halides.html (2474 words)

	jan14
		the halogen radical abstracts a hydrogen from the alkane
		Reaction of a chlorine radical with an alkane is exothermic
		Reaction of a bromine radical with an alkane is endothermic
	spot.pcc.edu /~chandy/242/jan14.html (360 words)

	Free Radical Mechanisms Menu (Site not responding. Last check: 2007-11-03)
		A brief explanation of the terms free radical and substitution.
		Free radical substitution of hydrogen atoms in the methyl group in methylbenzene by chlorine atoms in the presence of UV light (sunlight).
		The mechanism for the polymerisation of ethene under free radical conditions.
	www.chemguide.co.uk /mechanisms/frmenu.html (137 words)

	Karl's Calculus Tutor - 11.5 Hyperbolic Substitution
		If hyperbolic substitution is not part of your curriculum, then skip ahead (unless you're curious) to Partial Fractions, and don't worry, we will cover the methods to integrate the functions that are covered here later on.
		Indeed we later found that by completing the square we could use this same substitution to integrate a whole class of functions that had a quadratic under the radical -- but not all such functions.
		When you have an integrand involving a quadratic under a radical, we have seen that the first thing to do is complete the square.
	www.karlscalculus.org /hyper.html (2129 words)

	Chapter 11 (Site not responding. Last check: 2007-11-03)
		The allyl radical is a resonance hybrid of two resonance structures.
		Hyperconjugation is the delocalization of electrons (stabilization) through the overlap of a p orbital {in a radical or ion} with a sigma bond orbital of the alkyl group.
		In the radical there is one unpaired electron in the p orbital while in the cation, there are no electrons in the p orbital.
	web.njit.edu /~skawinsk/chem243/chap11/chap11.htm (2207 words)

	Free Radical Substitution
		Alkanes undergo free radical substitution reactions involving free radicals involving homolytic fission.
		All propagation reactions involve the reaction between one free radical and one normal molecule to produce another free radical and one normal molecule.
		The chlorine free radical reacts with a methane molecule, and cleaves a hydrogen from it.
	www.teachmetuition.co.uk /Chemistry/Organic/free_radical_substitution.htm (192 words)

	Substitution-Transfer-Abstraction-Displacement
		During the radical chlorination of methane, here, one of the propagation steps involves a hydrogen radical (a hydrogen atom) transferring from a methyl radical to a chlorine radical.
		This reaction could be regarded as an electrophilic substitution, with the borane electrophile substituting the sodium ion electrofuge (Lewis acid leaving group) from a hydride ion centre.
		During the radical chlorination of methane, here, one of the propagation steps involves a methyl radical abstracting a chlorine radical from chlorine, Cl, to give methyl chloride, CH Cl, and leaving a chlorine radical.
	www.meta-synthesis.com /webbook/21_stad/stad.html (2723 words)

	Option H Organic HL
		H.2.1 Describe the gas phase reactions of alkanes and methylbenzene with halogens in terms of free radical reactions.
		H.9.1 Discuss and explain the acidic properties of phenol and substituted phenols in terms of bonding.
		H.9.2 Discuss and explain the acidic properties of substituted alkanoic acids in terms of bonding.
	www.phuhs.org /academics/Science/Dull/Senior/option_h_organic__hl.htm (597 words)

	Radical
		For the video game developer, see Free Radical Design.
		Too much bilirubin, though, can lead to jaundice, which could eventually damage the central nervous system, while too much uric acid causes gout.
		An overview of the role of free radicals in biology and of the use of electron spin resonance in their detection may be found in a recent book: Rhodes C.J.: Toxicology of the Human Environment - the critical role of free radicals*, Taylor and Francis, London (2000).
	www.ibpassociation.org /encyclopedia/Chemistry/Radical.php (1289 words)

	jan16
		Think of your formal lab report as a document you may submit to your boss or as a student, add to your portfolio.
		Radicals generated by the interaction with metal ions.
		Radical Inhibitors - Covert a reactive radical into an unreactive radical.
	spot.pcc.edu /~chandy/242/jan16.html (296 words)

	Summary of 5 (Site not responding. Last check: 2007-11-03)
		This is a substitution reaction in which an antiseptic smelling compound is formed.
		Substitution reaction is defined as the replacement of one atom (or group of atoms) in a molecule by another atom (or group).
		In this type of substitution two of the delocalised [pi] electrons on the benzene ring are donated to the electrophile.
	www.wbateman.demon.co.uk /asa2sums/sum5.3/sum5.3.htm (976 words)

	[No title] (Site not responding. Last check: 2007-11-03)
		On the one hand, the removal of an H atom by Cl radical is an exothermic reaction step.
		The result is that free radical reactions of Br2 with alkanes are far more useful and selective than the same reaction with Cl2.
		In the case of alkenes (benzene is not considered an "alkene"), radical chlorination is a disaster, and radical bromination cannot be carried out using Br2.
	www.stolaf.edu /people/hansonr/chem247/ch9summary.txt (781 words)

	Course Materials
		As in radical processes, electron flow always occurs from the source of the electrons (tail of the arrow) to the recipient of the electrons (arrow head).
		Substitution - Substitutions occur when one functional group on a molecule is replaced by another functional group.
		Radical Addition - The starting material is usually either an alkene or alkyne and a radical initiator is present.
	www.citadel.edu /chemistry/chem207/orgmat.htm (2295 words)

	Alkane Reactivity
		Once a carbon radical is formed, subsequent bonding to a halogen atom (in the second step) can only occur at the radical site.
		Since carbon-carbon double bonds add chlorine and bromine rapidly in liquid phase solutions, free radical substitution reactions of alkenes by these halogens must be carried out in the gas phase, or by other halogenating reagents.
		Because alkyl radicals are important intermediates in many reactions, this stability relationship will prove to be very useful in future discussions.
	www.cem.msu.edu /~reusch/VirtualText/funcrx1.htm (1653 words)

	ORGANIC CHEMISTRY II - CHAPTER 16 LECTURE OUTLINE (Site not responding. Last check: 2007-11-03)
		The substitution mechanism is identical to halogenation and nitration.
		If substitution occurs slower than that observed for a benzene hydrogen, the substituent is said to be activating.
		The oxidation of arenes is useful in identifying the substitution pattern on the benzene ring.
	www.sbuniv.edu /~ggray/CHE3314/cp16outl.html (1172 words)

	Oxygen and Carbohydrates II
		The first pathway is a hydroxyl radical substitution reaction at the anomeric carbon forming D-cellobiose and methanol.
		The hydroxyl radical attacks the anomeric carbon displacing the methoxyl radical, or attacks the methyl displacing a cellobioxy radical.
		-cellobioside and hydroxyl radicals as the mechanism for cleaving the glycosidic linkages.
	chemistry.umeche.maine.edu /Fort/Oxygen2c.html (1024 words)

	CHE 123 Specific Objectives W 00
		Be able to write a free radical chain mechanism for the free radical halogenation of an alkane, including the structure of the free radical intermediates, the different ways of generating radicals, and all of the INITiation, PROPagation and TERMination steps.
		Be able to write a good mechanism for an electrophilic aromatic substitution (EAS) reaction (involving the arenium ion and showing all of the good resonance structures for this ion), and be able to predict and explain why a substituent will activate or deactivate an aromatic ring toward EAS.
		Benzyl compounds are usually quite reactive due to the stabilization of intermediate charges and radicals on the benzyl carbon by the benzene pi-system.
	condor.depaul.edu /~envirsci/TJM123SPOB00.html (1725 words)

	Radical Substitution in the Nickeladithiolene Ring in Bis(1-phenyl-1,2-ethenedithiolato)nickel(0) (Site not responding. Last check: 2007-11-03)
		Substitution of the 1-cyano-1-methylethyl group for hydrogen in the nickeladithiolene ring occurs in the reaction of bis(1-phenyl-1,2-ethenedithiolato)nickel(0) with 2,2'-azobis(isobutyronitrile).
		A radical mechanism is evidenced by the inhibition of the substitution in the presence of the radical scavenger TEMPO.
		The cis-trans isomerization and the exchange of dithiolato ligands are discussed in connection with the radical substitution.
	pubs.acs.org /cgi-bin/abstract.cgi/orgnd7/1996/15/i26/abs/om960698i.html (145 words)

	ORGANIC CHEMISTRY MECHANISMS AROMATIC HYDROCARBONS Arenes electrophilic substitution concentrated conc. nitric acid ...
		The electrophilic substitution of an arene - nitration
		The electrophilic substitution of an arene - chlorination
		The overall acylation reaction is the substitution of -H by RCO
	www.wpbschoolhouse.btinternet.co.uk /page06/OrgMechs4.htm (1759 words)

	Free Radical Homolytic Substitution by the Frontside Mechanism: Ab Initio Study of Homolytic Substitution Reactions at ...
		(frontside) for reactions of stannyl radical with distannane.
		for the reaction of silyl radical with distannane by the frontside mechanism to 104.5 kJ mol
		Except for reactions involving attack at the tin atom in methylstannane, we were unable to locate transition states for frontside attack at correlated levels of theory for reactions involving methyl radical.
	pubs.acs.org /cgi-bin/abstract.cgi/orgnd7/2000/19/i07/abs/om990886j.html (267 words)

	Ch4 : Radical Substitution Mechanism (Site not responding. Last check: 2007-11-03)
		Unlike the large majority of reactions that you will see in your organic chemistry course, radical mechanism require that fishhook curly arrows that represent the motion of a single electron are used.
		However, the mechanism for the bromination of methane is shown below, but the mechanism for chlorination or higher alkanes in the same.
		Heat or uv light cause the weak halogen bond to undergo homolytic cleavage to generate two bromine radicals and starting the chain process.
	www.chem.ucalgary.ca /courses/351/Carey5th/Ch04/ch4-4-2.html (223 words)

	Current Organic Chemistry, Volume 7, No. 8, 2003
		In the section of transition metal catalyzed fixation of carbon dioxide, we mainly focus on the catalytic process of carbon dioxide insertion reactions promoted by metal catalysts and the emphasis is put on the preparation of the corresponding carbonates or carbamates from CO and their further transformations.
		Their lack of reactivity is usually due to strain (cycloalkyl and polycycloalkyl halides), steric (cycloalkyl, polycycloalkyl and neopentyl halides), or electronic factors (unactivated aromatic, vinyl halides and perfluoroalkyl halides).
		Conversely, there is a class of substrates, for which substitution can be achieved through both polar and ET mechanisms; however, the ET pathway is favored in some systems (i.e.: alkyl halides with EWG).
	www.bentham.org /coc/contabs/coc7-8.htm (727 words)

	Nucleophilic Substitution Reactions
		Nucleophilic substitution reactions are an important class of reactions that allow the interconversion of functional groups, for example R-OH ®
		Nucleophilic substitution will be explored in much more detail in chapter 8.
		This pathway is a concerted process (single step) as shown by the following reaction coordinate diagrams, where there is simultaneous attack of the nucleophile and displacement of the leaving group.
	www.mhhe.com /physsci/chemistry/carey/student/olc/ch04nucle.html (1065 words)

	Chemistry 391: Special Topics (Site not responding. Last check: 2007-11-03)
		MO picture; three electron bonding; charge and spin coupling and uncoupling in anion radicals; distonic anion radicals; the shape of the SOMO of anion radicals (TCNE anion radical).
		Radical scavengers; radical traps; radical inhibitors; radical probes and clocks.
		Radical substitution reactions (halogenation, autoxidation, tin hydride reduction).
	research.cm.utexas.edu /nbauld/teach/course4.html (194 words)

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