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Ring oxygenation

Depending on the oxidation conditions, benzene and its substituted derivatives, and polycyclic aromatic hydrocarbons may be converted to phenols and quinones. Alkoxylation and acyloxylation are also possible. Addition reactions may afford dihydrodiols, epoxides, and endoperoxides. [Pg.491]


Orienf fhe Haworth formula of the carbohydrate with the ring oxygen at the back and the anomeric carbon at the right... [Pg.1034]

Eleclron pair on ring oxygen can slabihze carbocalion al anomenc posilion only... [Pg.1045]

Rea.ctlons, Butyrolactone undergoes the reactions typical of y-lactones. Particularly characteristic are ring openings and reactions in which ring oxygen is replaced by another heteroatom. There is also marked reactivity of the hydrogen atoms alpha to the carbonyl group. [Pg.110]

Butyrolactone and hydrogen sulfide heated over an alumina catalyst result in replacement of ring oxygen by sulfur (151). [Pg.110]

The main raw material required for the production of viscose is ceUulose (qv), a natural polymer of D-glucose (Fig. 1). The repeating monomer unit is a pair of anhydroglucose units (AGU). CeUulose and starch (qv) are identical but for the way in which the ring oxygen atoms alternate from side to side of the polymer chain (beta linkages) in ceUulose, but remain on the same side (alpha linkages) in starch. [Pg.345]

Fig. 3. Spectral sensitizing dyes for silver haUdes. (a) Blue sensitizers (400—500 nm) are designated BN (b) green sensitizers (500—600 nm) are designated GN (the ring oxygen may be replaced by N(R)) (c) red sensitizers (600—700 nm) are designated RN (d) MN designates a merocyanine dye and (e),... Fig. 3. Spectral sensitizing dyes for silver haUdes. (a) Blue sensitizers (400—500 nm) are designated BN (b) green sensitizers (500—600 nm) are designated GN (the ring oxygen may be replaced by N(R)) (c) red sensitizers (600—700 nm) are designated RN (d) MN designates a merocyanine dye and (e),...
An electronegative substituent adjacent to a ring oxygen atom also shows a preference for an axial orientation. This is known as the anomeric effect , and is particularly significant to the conformations of carbohydrates (B-71MI20100, B-83MI20100). [Pg.9]

Amines are insufficiently nucleophilic to react with most azoles which do not contain a ring oxygen, and the stronger nucleophile NH2 is required. When treated with amide ions, thiazoles can be aminated in the 2-position by NaNHa at 150 °C. Only TV-substituted condensed imidazoles such as 1-alkylbenzimidazole react in such Chichibabin reactions. Imidazoles are aminated by alkaline NH2OH. [Pg.65]

A point to be emphasized about glycoside fonnation is that, despite the presence of a number of other hydroxyl groups in the carbohydrate, only the anomeric hydroxyl group is replaced. This is because a carbocation at the anomeric position is stabilized by the ring oxygen and is the only one capable of being fomned under the reaction conditions. [Pg.1045]

Electron pair on ring oxygen can stabilize carbocation at anomeric position only. [Pg.1045]

Auwers and others soon discovered that the transformation 3 —> 6 did not consistently give flavonols such as 2. For example, alcoholic alkali treatment of dibromide 11 produced 2-benzoyl-benzofuran-3-one 12 instead of the corresponding flavonol. The same observation was made by Robert Robinson in a failed attempt to make datiscetin in 19257 It has reported that when there is a meta (to the coumarone ring oxygen) substituent such as methyl or methoxy, flavonol formation is hindered, whereas methyl, methoxy, and chlorine substituents at the ortho and para positions are conducive to flavonol formation. ... [Pg.263]

While the above studies were in progress results from dioxane derivatives were published (19,94) which support all of the comments and cautions we have made above. Additional reports have been made of a long-range coupling across a ring oxygen in an unsaturated pentopy-ranose derivative (17) and in a saturated furanose derivative (20). [Pg.254]


See other pages where Ring oxygenation is mentioned: [Pg.815]    [Pg.447]    [Pg.4]    [Pg.36]    [Pg.307]    [Pg.45]    [Pg.16]    [Pg.100]    [Pg.105]    [Pg.735]    [Pg.26]    [Pg.187]    [Pg.198]    [Pg.151]    [Pg.222]    [Pg.702]    [Pg.815]    [Pg.1059]    [Pg.174]    [Pg.448]    [Pg.594]    [Pg.287]    [Pg.18]    [Pg.19]    [Pg.188]    [Pg.329]    [Pg.50]    [Pg.59]    [Pg.161]    [Pg.175]    [Pg.220]    [Pg.252]    [Pg.253]    [Pg.253]    [Pg.415]    [Pg.422]    [Pg.732]   


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Aluminium-oxygen rings

Aromatic rings oxidation with molecular oxygen

Aromatics ring oxygenation

Arsenic-, Antimony- and Bismuth-Oxygen Rings

Arsenic-oxygen rings

Boron-oxygen rings

Carb-34. Replacement of Ring Oxygen by Other Elements

Carbocations oxygen ring substituents

Carbon ring oxygen replacement

Carbon-boron-sulfur-oxygen rings

Carbon-nitrogen-oxygen rings

Carbon-nitrogen-oxygen-sulfur rings

Carbon-oxygen bonds, furanose rings

Carbon-oxygen-nitrogen-metal rings

Carbon-oxygen—sulfur rings

Carbon-phosphorus-oxygen rings

Carbon-phosphorus-oxygen-metal rings

Cyclic nitrogen-oxygen ring

Eight-ring Oxygen Compounds

Electronegative oxygen rings

Electrophilic Attack on Ring Oxygen

Fission of Oxygenated Rings

Five Ring Oxygen Systems

Five-membered Nitrogen- and Oxygen-containing Rings

Five-membered Oxygen-containing Rings

Formation and Cleavage of the Oxygen Ring in Sugars

Four-membered Rings containing Oxygen and One Sulphur Atom

Four-membered Rings containing Sulphur and Oxygen

Group 16 systems sulfur-oxygen rings

Heterocycles can have many nitrogens but only one sulfur or oxygen in any ring

Heterocycles containing both oxygen and sulfur in the same ring

Heterocyclic Oxygen Compounds with Three or More Rings

Hydrogenation of Oxygen- and Sulfur-containing Aromatic Ring Systems

Medium-sized-ring Oxygen-containing Heterocycles

Miscellaneous Fused Rings that Include Oxygen

Modifications at C-5 and Substitution for the Ring Oxygen

Molecular oxygen, oxidation ring opening

Nitrate esters from the ring-opening of strained oxygen heterocycles

Nitrogen, ring oxygen replacement

Nitrogen- and Oxygen-containing Rings

Nomenclature ring oxygen replacement

Oxygen Function at C-4 of the Piperidine Ring

Oxygen atoms, ring-opening

Oxygen heterocycles, ring opening

Oxygen nucleophiles, ring opening

Oxygen ring

Oxygen ring

Oxygen ring in, formation and cleavage

Oxygen ring opening

Oxygen-containing Compounds with More than One Ring

Oxygen-containing furan-ring derivatives

Oxygen-containing medium-sized-ring

Oxygen-sulfur rings

Oxygenated structures, ring expansion

Phosphorus ring oxygen replacement

Phosphorus, replacing ring oxygen

Phosphorus-oxygen rings

Ring Systems Containing One Oxygen or Sulfur

Ring opening of oxygen heterocycles

Ring oxygen replacement

Ring oxygenation introduction

Ring with oxygen-based nucleophiles

Ring-opening reactions by oxygen nucleophiles

Ring-oxygen substitution

Rings containing Oxygen

Rings with Nitrogen and Oxygen

Rotating ring-disc electrode oxygen reduction

Silicon-, Germanium- and Tin-Oxygen Rings

Silicon-oxygen rings (cyclosiloxanes

Silicon-oxygen-nitrogen rings

Six Ring Oxygen Systems

Six-Membered Rings containing Oxygen or Sulphur

Six-membered Nitrogen- and Oxygen-containing Rings

Six-membered Rings with More than One Oxygen

Six-membered aromatic heterocycles can have oxygen in the ring

Six-membered oxygen-containing rings

Six-membered oxygen-containing rings saturated, analysis

Six-membered ring heterocycles containing one oxygen atom

Strained oxygen heterocycles, ring-opening

Sugars oxygen ring in, formation and cleavage

Sulfur-Nitrogen Rings Containing Exocyclic Oxygen

Synthesis of Prenyl Oxygen Ring Phenolic Compounds

Synthesis of Rings with One Oxygen Atom

Tellurium-oxygen rings

With oxygen-substituted ring systems

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