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Activating group

As mentioned above, the activators increase the reactivity of the ring than that of benzene. The substitution primarily occurs in the ortho and para positions of the ring relative to the activating group. For this reason, activators are also called ortho/para directors. Let us analyze this with an example. In the following reaction, phenol is nitrated. Notice that phenol contains a hydroxyl group (-OH) which is an ortho/para activator. So the substitution occurs at ortho and para positions with respect to the -OH group. [Pg.250]

Because the attack on the ortho or para attack results in more stable cation intermediates, those intermediates are formed faster and thus the resulting products from those intermediates are the predominant products. [Pg.251]

Deactivators make the ring less reactive than benzene. There are two types of deactivators - ortho/para and meta deactivators. [Pg.252]

The substituent acyl group has a highly polarized carbon-oxygen double bond. [Pg.253]

The positively charged carbon withdraws electron density from the benzene ring inductively. This accounts for the deactivation (less reactivity than benzene) of the ring toward electrophilic substitution. [Pg.253]

Polyacylation is not observed, because introduction of an acyl group deactivates the ring toward further acylation. This will be explained in more detail in the upcoming sections. [Pg.873]

8 Identify whether each of the following compounds can be made using a direct Friedel-Crafts alkylation or whether it is necessary to perform an acylation followed by a Clemmensen reduction to avoid carbocation rearrangements  [Pg.873]

9 The following compound cannot be made with either a Friedel-Crafts alkylation or acylation. Explain. [Pg.873]

10 A Friedel-Crafts acylation is an electrophilic aromatic substitution in which the electrophile (E ) is an acylium ion. There are other methods of forming acylium ions, such as treatment of an anhydride with a Lewis acid. The resulting acylium ion can also be attacked by a benzene ring, resulting in acylation of the aromatic ring. With this in mind, draw the mechanism of the following transformation  [Pg.873]

Thus far, we have dealt only with reactions of benzene. We now expand our discussion to include reactions of aromatic compounds that already possess substituents, such as toluene. [Pg.873]


The pathway model makes a number of key predictions, including (a) a substantial role for hydrogen bond mediation of tunnelling, (b) a difference in mediation characteristics as a function of secondary and tertiary stmcture, (c) an intrinsically nonexponential decay of rate witlr distance, and (d) patlrway specific Trot and cold spots for electron transfer. These predictions have been tested extensively. The most systematic and critical tests are provided witlr mtlrenium-modified proteins, where a syntlretic ET active group cair be attached to the protein aird tire rate of ET via a specific medium stmcture cair be probed (figure C3.2.5). [Pg.2978]

Hydrogen bonding of water to the activating group of (for normal-electron demand Diels-Alder reactions) the dienophile constitutes the second important effect". Hydrogen bonds strengthen the electron-withdrawing capacity of this functionality and thereby decrease the HOMO-LUMO gap... [Pg.43]

Of course, we must now remove the activating group, COiEt in this case, just as we had to remove the protecting group before. How might we do this ... [Pg.19]

The acetoacetate enolate ion (A in frame 54) is a reagent for the synthon B, the acetone anion. We shall discover how to add the COiEt activating group later. [Pg.19]

Only the more stable enolate (101 A) is formed and this reacts well with allyl bromide. This activating group (CHO) can be removed by basecatalysed hydrolysis. Mechanism ... [Pg.32]

The one-carbon addition we used in frames 98 and 101 is all right if we just want to add an activating group to a readily available ketone, but is not otherwise good synthetic practice ... [Pg.33]

If we want to make a simple 1,5-diketone we may have to use an activating group like C02Et to control the reaction. How would you make TM 119 ... [Pg.38]

Synthesis Though we could follow the stepwise pattern of the disconnections, it is easier to add an activating group to the acetone molecule so that our starting materials are two molecules of acetoaeetate and formaldehyde. It turns out that Hagemann s ester can be made in two steps without having to alkylate the Mannich base ... [Pg.41]

Synthesis We shall need an activating group, and our starting material is actually TM 104 ... [Pg.57]

Synthesis An activating group is necessaiy to control the Michael reaction ... [Pg.64]

Synthesis We shall need the usual activating group for both Michael reactions it can t be a CO2R group as there isn t room, so it will have to be an enamine. The synthesis is therefore ... [Pg.67]

We shell need a strong base as there s no room for an activating group. [Pg.68]

We must next disconnect the six-membered ring and the only way we know to set up these chiral centres specifically is by the Diels-Alder reaction. Two alternative sites for the double bond are possible if we convert our NHi to give the necessary activating group (NOi)... [Pg.87]

The reactions described so far can be considered as alkylation, alkenylation, or alkynylation reactions. In principle all polar reactions in syntheses, which produce monofunctional carbon compounds, proceed in the same way a carbanion reacts with an electropositive carbon atom, and the activating groups (e.g. metals, boron, phosphorus) of the carbanion are lost in the work-up procedures. We now turn to reactions, in which the hetero atoms of both the acceptor and donor synthons are kept in a difunctional reaction produa. [Pg.50]

The growing importance of cyclopropane derivatives (A. de Meijere, 1979), as synthetic intermediates originates in the unique, olefin-like properties of this carbocycle. Cyclopropane derivatives with one or two activating groups are easily opened (see. p. 69f.). Some of these reactions are highly regio- and stereoselective (E. Wenkert, 1970 A, B E. J. Corey, 1956 A, B, 1975 see p. 70). Many appropriately substituted cyclopropane derivatives yield 1,4-difunctional compounds under mild nucleophilic or reductive reaction conditions. Such compounds are especially useful in syntheses of cyclopentenone derivatives and of heterocycles (see also sections 1.13.3 and 4.6.4). [Pg.76]

These fibers may find use in controUed release of dmgs, bactericides, and corrosion prevention chemicals (103). Fibers with different active groups have been made for sorption of chemicals. These fibers are designed to replace granular sorbents for air purification, for example, in air filtration masks (104). [Pg.285]

Flotation reagents are used in the froth flotation process to (/) enhance hydrophobicity, (2) control selectivity, (J) enhance recovery and grade, and (4) affect the velocity (kinetics) of the separation process. These chemicals are classified based on utili2ation collector, frother, auxiUary reagent, or based on reagent chemistry polar, nonpolar, and anionic, cationic, nonionic, and amphoteric. The active groups of the reagent molecules are typically carboxylates, xanthates, sulfates or sulfonates, and ammonium salts. [Pg.46]

Activating groups other than nitro or cyano have extended the versatility of exchange-duorination reactions —CHO (59,60) —COCl (60) —CO2R... [Pg.319]

Nucleophilic Displacement Reactions. The presence of activating groups, eg, o,p mX.1.0 groups, makes aromatic fluorine reactive in nucleophilic displacement reactions. This has been demonstrated by deterrnination of the relative fluorine—chlorine displacement ratios from the reaction of halonitroben2enes with sodium methoxide in methanol (137) F is displaced 200—300 times more readily than Cl. [Pg.321]

Resonance effects are the primary influence on orientation and reactivity in electrophilic substitution. The common activating groups in electrophilic aromatic substitution, in approximate order of decreasing effectiveness, are —NR2, —NHR, —NH2, —OH, —OR, —NO, —NHCOR, —OCOR, alkyls, —F, —Cl, —Br, —1, aryls, —CH2COOH, and —CH=CH—COOH. Activating groups are ortho- and para-directing. Mixtures of ortho- and para-isomers are frequently produced the exact proportions are usually a function of steric effects and reaction conditions. [Pg.39]


See other pages where Activating group is mentioned: [Pg.321]    [Pg.177]    [Pg.44]    [Pg.57]    [Pg.66]    [Pg.68]    [Pg.202]    [Pg.206]    [Pg.207]    [Pg.4]    [Pg.119]    [Pg.348]    [Pg.297]    [Pg.940]    [Pg.1109]    [Pg.15]    [Pg.318]    [Pg.208]    [Pg.209]    [Pg.397]    [Pg.363]    [Pg.461]    [Pg.475]    [Pg.28]    [Pg.80]    [Pg.310]    [Pg.516]    [Pg.63]    [Pg.63]    [Pg.68]    [Pg.39]   
See also in sourсe #XX -- [ Pg.38 , Pg.101 , Pg.323 , Pg.324 ]

See also in sourсe #XX -- [ Pg.340 , Pg.341 , Pg.360 ]

See also in sourсe #XX -- [ Pg.340 , Pg.341 , Pg.360 ]

See also in sourсe #XX -- [ Pg.685 , Pg.686 ]

See also in sourсe #XX -- [ Pg.691 ]

See also in sourсe #XX -- [ Pg.509 ]

See also in sourсe #XX -- [ Pg.169 ]

See also in sourсe #XX -- [ Pg.277 ]




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2-Oxazolines activating groups

5- Nitropyrimidine, ring transformation reaction with active methylene groups

A-Aminosulfonic acid amides groups, active

Acetonitrile, carboxylic group activation

Acidic groups biological activity

Activate neighboring functional groups

Activated alkyl groups and polynuclear aromatics

Activated carbon acidic groups

Activated carbon basic groups

Activated carbon pyrone groups

Activated carbon surface functional groups

Activated halogen groups

Activated halogen groups, compounds

Activated vinyl group

Activating Oxygen as a Leaving Group

Activating and deactivating groups

Activating group (aromatic acidity and

Activating group (aromatic explanation

Activating group characteristics

Activating group effects

Activating group explanation

Activating group methoxycarbonyl

Activating groups Substituents that, when

Activating groups addition

Activating groups in electrophilic aromatic

Activating groups meta directors

Activating groups ortho—para directors

Activating groups substituents

Activating groups substitution

Activating groups, aromatic substitution

Activation amino groups

Activation by amino group

Activation effects groups

Activation energies amino group restricted rotation

Activation energy group

Activation of Carbonyl Groups and Alcohols

Activation of Dioxygen by Cobalt Group

Activation of Dioxygen by Cobalt Group Metal Complexes

Activation of carbonyl groups by iminium ion formation

Activation of the carbonyl group

Activation target groups

Active Group exchange

Active Group identification

Active groups

Active groups

Active methylene group

Active site group theories

Active transport group translocation

Activity coefficient group contribution model

Activity coefficients, limiting group

Activity group VIII metals supported

Activity, glycosyl group

Activity-based probes reactive groups

Acylamino group, activating effects

Alcohols hydroxy group activation

Aldehydes from activated methyl groups

Alkyl groups, activating effect

Alkyl polysilane, optically active groups

Amino group activated, peptide

Amino groups activation parameters

Amino groups active-esters methods

Anomeric Activating Groups and Stereoselectivity

Anomeric activating groups

Antioxidative activity hydroxyl groups kinds

Antitumor activity group 12

Arenes and Hetarenes Activated by the Nitro Group

Arenium ions activating groups

Aromatic compounds, activation groups

Aromatic, activating groups

Azine substitution , activation acyl groups, electronic effects

Azine substitution , activation acyloxy groups, electronic effects

Azine substitution , activation acylthio group, electronic effects

Azine substitution , activation alkyl leaving groups

Azine substitution , activation alkylsulfonyl leaving groups

Azine substitution , activation alkylthio group, electronic effects

Azine substitution , activation alkylthio leaving groups

Azine substitution , activation amino leaving groups

Azine substitution , activation ammonio groups, displacement

Azine substitution , activation aryl groups, electronic effects

Azine substitution , activation aryloxy groups, electronic effects

Azines—continued bicyclic, activation by benzo group

Basicity, silanol group activation

Biotin-Hydrazide Modification of Bisulfite-Activated Cytosine Groups

Blood group B-active

Blood-group active glycolipids

Blood-group active glycoproteins

Carbonyl groups, activation

Carboxy group activation

Carboxy group activation esterification

Carboxy group activation mechanism

Carboxy group, activated

Carboxyl group activation

Carboxyl group, activated

Carboxyl groups active site

Carboxylic acids hydroxy group activation

Catalyst activity and functional group

Catalyst activity and functional group tolerance

Catalytic groups, active site

Catalytically active group

Chemically-active surface groups

Compounds with Activated Methyl, Methylene and Methine Groups

Compounds with activated halogen groups

Control groups active

Cyano group activating effects

Diphenylphosphinoyl group, activation

Effects of Activating Groups

Electrochemical Properties of Active Groups

Electrochemical Properties of Protein Macromolecules and Their Active Groups

Enzyme biological activity, sulfhydryl groups

Formate, active methyl groups from

Functional group activation

Functional group activation bioactivation

Functional group activation carbonyl compounds, unsaturated

Functional group activation carboxylic acids

Functional group activation hydrazines

Functional group activation reactive intermediates

Glycol groups, activation

Glycosphingolipids group-active

Glycosyl groups, active

Group Activation

Group Activation

Group Learning Activities

Group NMR active nuclei

Group VIII metals dehydrogenation activities

Group VIII metals hydrogenation activities

Group VIII metals hydrogenolysis activities

Group VIII metals methanation activity

Group biological activity values

Group-transfer reactions active carriers

Herbicide groups, structure-activity

Herbicide groups, structure-activity relationships

Hydrogenolysis of activated keto groups

Hydroxy group activation

Hydroxy group activation ester synthesis

Hydroxyl groups activation with

Imidazoles 2-silyl groups, active

LC Copolymers Containing Both Nematogenic (or Smectogenic) and Active Side Groups

Leaving group activation, peptide hydrolysis

Leaving group selective activation

Leaving groups, active

Light-active donor group

Mesylates hydroxy group activation

Metabolic activation, organic functional groups

Methoxycarbonyl as activating group

Methyl and methylene groups, active

Methyl groups activating effects

Methyl groups active

Methylene groups, activated

Methylene groups, activated Michael-type addition

Methylene groups, activated aldol condensation

Methylene groups, activated alkylation

Methylene groups, activated iodination

Methylene groups, activated periodate oxidation

Near-infrared activated groups

Nitrile group activation

Nitro compounds Methyl groups, active

Nitro group activating effects

Nitro group, activation

Nitrogen-Activating Group Effects

Nitroso compounds reaction with active methylene groups

Nucleophilic aromatic substitution activating groups, effects

Nucleophilic aromatic substitution nitro-group activated

Of activated methylene group

Of blood group I active

Of the active groups

Oligothiophenes containing redox-active groups

Oligothiophenes containing surface-active groups

Optical activity space-groups

Oxidation of active methylene groups

Oxidation, oxazole reactions activating group

Oxirane polymerization active groups

Oxygen Bridge Activation by an Electron-Donating Group at the Bridgehead Carbon

Ozonolysis activating group

Peptide amido groups active)

Perfluoroacetone, reaction with methylene groups, activ

Perfluoroalkyl group, activation

Periodate oxidation active methylene groups

Phosphorus with methylene groups, active

Phosphoryl group transfer active carriers

Photo-active groups

Platinum, catalytic activity with functional groups

Preparation of polymethylphenylsiloxanes with active hydrogen atoms and vinyl groups at the silicon atom

Pyrrole activated methylene groups

Quaternary N groups and anticholinesterase activity quaternization

Reactions of azides with active methylene groups

Redox active groups

Redox-active prosthetic groups

Reduction of activated carbonyl groups

Remote chiral groups, optically active

Ruthenium, catalytic activity with functional groups

Selective activation with three leaving groups

Solubility group activity)

Special Activity Group on Accident

Special Activity Group on Accident Reduction

Stereochemical Activity of Lone Pairs in Heavier Main-group Element Compounds

Structure-activity relationship groups

Structure-activity relationship substituent groups

Structure-activity relationships specific substituent groups

Substitution SnAt, activating groups

Sulfhydryl groups activity

Sulfhydryl groups, metal binding active site

Sulfonation hydroxy group activation

Sulfonium salts groups, active

Surface active agents hydrophilic group

Surface active agents hydrophobic group

Surface active agents lipophilic group

Surface active agents lipophobic group

Surface hydroxyl groups activation

Surface-active functional groups

Surface-active groups

Target groups of activation

Thermally activated phenyl group

Thermo-active group

Thioesters to activate carboxyl groups

Tosylates hydroxy group activation

Transformation of active end-groups

Transition Metals as Protecting, Activating, and Directing Groups

Triflates hydroxy group activation

Trifluoromethyl groups nitro displacement activation

UNIFAC method functional group activity coefficient

Universal Functional Group Activity

Universal Functional Group Activity UNIFAC)

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