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Group Activation

A white solid, m.p. 178 C. Primarily of interest as a brominaling agent which will replace activated hydrogen atoms in benzylic or allylic positions, and also those on a carbon atom a to a carbonyl group. Activating influences can produce nuclear substitution in a benzene ring and certain heterocyclic compounds also used in the oxidation of secondary alcohols to ketones. [Pg.69]

An alkyl group activates all nuclear positions, the 0- and p-positions more than the r-position. The activation is not very strong. [Pg.163]

C—H bonds are polarized by attached unsaturated carbon substituents. Such groups "activate" the neighbouring CHj, CHp or CH groups in the following order CR=NR > COR > CN > COOR > CR = NR > Ph > CR=CRj. Two activating substituents reinforce each other. [Pg.9]

In a sophisticated variation of the Knoevenagel condensation ("Panizzi ) methyl 3,3-dimethoxypropanoate (from ketene and dimethoxymethenium tetrafluoroborate D.J. Crosby, 1962) is used as a d -reagent. Because only one carbonyl group activates the methylene group, a strong base with no nucleophilic properties (p. 10) has to be used. A sodium-sand mixture, which presumably reacts to form silicate anions in the heat, was chosen... [Pg.58]

The amino group activates the thiazole ring toward electrophilic centers. This point is illustrated by the rate constants of the reaction between 2-dialkylaminothiazoles (32) and methyl iodide in nitromethane at 25 C (Scheme 23) (158). The steric effects of substituents on nitrogen are... [Pg.32]

Hydroxyl alkoxy and acyloxy groups activate the ring to such an extent that bromina tion occurs rapidly even in the absence of a catalyst... [Pg.495]

Acrylamide, C H NO, is an interesting difiinctional monomer containing a reactive electron-deficient double bond and an amide group, and it undergoes reactions typical of those two functionalities. It exhibits both weak acidic and basic properties. The electron withdrawing carboxamide group activates the double bond, which consequendy reacts readily with nucleophilic reagents, eg, by addition. [Pg.133]

Nucleophilic Displacement Reactions. The strong electron-withdrawing effect of a trifluoromethyl group activates ortho and para halogen toward nucleophilic attack. Such chlorine labiUty is utili2ed in the manufacture of crop control chemicals containing trifluoromethyl and nitro groups. [Pg.329]

A tertiary carbonium ion is more stable than a secondary carbonium ion, which is in turn more stable than a primary carbonium ion. Therefore, the alkylation of ben2ene with isobutylene is much easier than is alkylation with ethylene. The reactivity of substituted aromatics for electrophilic substitution is affected by the inductive and resonance effects of a substituent. An electron-donating group, such as the hydroxyl and methyl groups, activates the alkylation and an electron-withdrawing group, such as chloride, deactivates it. [Pg.48]

Halogenation. The presence of the amino group activates the ortho and para positions of the aromatic ring and, as a result, aniline reacts readily with bromine or chlorine. Under mild conditions, bromination yields 2,4,6-trihromoaniline [147-82-0]. [Pg.230]

Electrophilic substitution reactions of diarylamines are easily accompHshed since the amino group activates the aromatic ring. Thus, DPA reacts with bromine or chlorine to form the 2,2H,4 tetrahalo derivative nitration usually produces the trinitro compound. [Pg.243]

UNIFAC andASOG Development. Pertinent equations of the UNIQUAC functional-group activity coefficient (UNIFAC) model for prediction of activity coefficients including example calculations are available (162). Much of the background of UNIFAC involves another QSAR technique, the analytical solution of groups (ASOG) method (163). [Pg.249]

Figure 3 The chemical structures of the ligands used in the molecular modeling study of the Di dopamine receptor. The ligands were divided into two groups (active and inactive) based on their pharmacological properties. The hypothesized pharmacophoric elements are shown in bold. Figure 3 The chemical structures of the ligands used in the molecular modeling study of the Di dopamine receptor. The ligands were divided into two groups (active and inactive) based on their pharmacological properties. The hypothesized pharmacophoric elements are shown in bold.
Performance based total productive maintenance is based on the promotions of PM through motivation management, autonomous small group activities. [Pg.723]

Total participation of all employees includes autonomous maintenance by operators through small group activities. [Pg.724]

The close structural similarities between polychloroprene and the natural rubber molecule will be noted. However, whilst the methyl group activates the double bond in the polyisoprene molecule the chlorine atom has the opposite effect in polychloroprene. Thus the polymer is less liable to oxygen and ozone attack. At the same time the a-methylene groups are also deactivated so that accelerated sulphur vulcanisation is not a feasible proposition and alternative curing systems, often involving the pendant vinyl groups arising from 1,2-polymerisation modes, are necessary. [Pg.295]

The mfluoromethyl group activates the fluorine in position 4 ofperfluorotolu ene toward reaction with carbon nucleophiles Examples on che use of perfluoro-toluene as an arylation agent abound, and in all cases, the 4-fluonne atom is replaced predommantly or exclusively [% 87,88,89, 90 (equation 48) In perjluoromesity-lene, the aromatic fluorine atoms are activated toward Ar reaction, and a reaction... [Pg.516]

Although one trifluoromethyl group activates an alkene as a dienophile, two or more can actually inhibit dienophilic reactivity, as evidenced by the fact that... [Pg.819]

An improvement in this protocol makes use of trimethylsilylcyanide. This reagent carries out both steps in one pot (47 48). The trimethylsilyl group activates... [Pg.346]

The acid cleavage of the aryl— silicon bond (desilylation), which provides a measure of the reactivity of the aromatic carbon of the bond, has been applied to 2- and 3-thienyl trimethylsilane, It was found that the 2-isomer reacted only 43.5 times faster than the 3-isomer and 5000 times faster than the phenyl compound at 50,2°C in acetic acid containing aqueous sulfuric acid. The results so far are consistent with the relative reactivities of thiophene upon detritia-tion if a linear free-energy relationship between the substituent effect in detritiation and desilylation is assumed, as the p-methyl group activates about 240 (200-300) times in detritiation with aqueous sulfuric acid and about 18 times in desilylation. A direct experimental comparison of the difference between benzene and thiophene in detritiation has not been carried out, but it may be mentioned that even in 80.7% sulfuric acid, benzene is detritiated about 600 times slower than 2-tritiothiophene. The aforementioned consideration makes it probable that under similar conditions the ratio of the rates of detritiation of thiophene and benzene is larger than in the desilylation. A still larger difference in reactivity between the 2-position of thiophene and benzene has been found for acetoxymercuration which... [Pg.44]

The effect of a carboxy group is illustrated by the reactivity of 2-bromopyridine-3- and 6-carboxylic acids (resonance and inductive activation, respectively) (cf. 166) to aqueous acid under conditions which do not give hydroxy-debromination of 2-bromopyridine and also by the hydroxy-dechlorination of 3-chloropyridine-4-car-boxylic acid. The intervention of intermolecular bifunctional autocatalysis by the carboxy group (cf. 237) is quite possible. In the amino-dechlorination (80°, 4 hr, petroleum ether) of 5-carbethoxy-4-chloropyrimidine there is opportunity for built-in solvation (167) in addition to electronic activation. This effect of the carboxylate ion, ester, and acid and its variation with charge on the nucleophile are discussed in Sections I,D,2,a, I,D,2,b, and II,B, 1. A 5-amidino group activates 2-methylsulfonylpyridine toward methanolic am-... [Pg.228]

A cyano group produces practical reactivity (methanolic CH30, 66°, < 3hr) by its presence in 2-chloro-3-cyano-6-methylpyridine, opposing the deactivating effect of a methyl group, and on other 2-chloropyridines (see references 3-6 in ref. 140). The cyano group activates 3-cyano-6,6-diphenyl-2-methoxypyrazine (168) (pre-... [Pg.228]

Chapman and co-workershave shown that, in the reactions of nitro-2-chloropyridines with piperidine, aryl amines, or pyridine bases, a 5-nitro group activates more than a 3-nitro group (cf. Table VII, p. 276). [Pg.238]

The presence of an TV-oxide group activates the 1,2,4-triazine ring toward electrophilic attack, for instance, in halogenation reactions. Thus, 3-methoxy- and 3-amino(alkylamino)-1,2,4-triazine 1-oxides 16 react easily with chlorine or bromine to form the corresponding 6-halo-1,2,4-triazine 1-oxides 17 (77JOC3498, 78JOC2514). [Pg.268]

This collection of worksheets (about three per chapter) is for students to use in collaborative groups. Designed to stimulate group activity and discussion, the questions provided on each worksheet are equally conceptually and quantitatively oriented. Also included are instructions for use, information on how to guide student discussion, and supporting data on the success of cooperative learning at the University of Connecticut... [Pg.725]


See other pages where Group Activation is mentioned: [Pg.910]    [Pg.239]    [Pg.207]    [Pg.436]    [Pg.15]    [Pg.53]    [Pg.34]    [Pg.39]    [Pg.236]    [Pg.532]    [Pg.565]    [Pg.429]    [Pg.488]    [Pg.150]    [Pg.229]    [Pg.229]    [Pg.230]    [Pg.278]    [Pg.384]    [Pg.397]   


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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

Activating groups

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 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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