Found inside – Page 51This resonance stabilization is not available to an alkoxide ion ( Scheme 2.17 ) ... carbocation which is formed is a resonance hybrid , and consequently Cl ... 4. Simple 1º and 2º-alcohols in the gaseous state lose hydrogen when exposed to a hot copper surface. 17.3, p. 595) The activation energy, E a, reflects the stability of the transition state, which depends upon the structure of the substrate, the nucleophile, and the leaving group. Found inside – Page 213This resonance allows the anionic charge to delocalize. In contrast, the alkoxide anion is described by a single Lewis structure having the anion centered ... In contrast, the alkoxide ion has no resonance stabilisation since there is no π system. Lewis diagrams 1, 2, and 3 are called resonance forms, resonance structures, or resonance contributors of the nitrate ion. The alkoxide ion that just got eliminated is basic, and comes back to pinch a proton from the carboxylic acid, forming an alcohol and leaving a carboxylate ion. The phenolate ion can also be stabilised by resonance but the charge ends up on C atoms. Found inside – Page 428Interpretation nature O H [Resonating cannonical ofacidic : OH +OH +OH O +OH ... + H + [Resonance structure of phenoxidei on] Both phenol and phenoxide ion ... Penoxide ion formed is stabilised by resonance. i) The alkoxide ion (RO-) - the negative charge is confined to the oxygen and is not spread over the alkyl group. 2. Found inside – Page 66Of course, both the carboxylic acid and its conjugate anion are resonance ... limiting form makes only a small contribution to the resonance structure. Found inside – Page 145... while in phenoxide, the resonating structures are not equivalent and alkoxide ions do not exhibit resonance. N2O4 2NO2 1 – α 2α Total moles at eqm. Step 2: Since the other three bonds are strong covalent bonds which cannot break . Found inside – Page 428Interpretation nature O H [Resonating cannonical ofacidic : OH +OH +OH O +OH ... + H + [Resonance structure of phenoxidei on] Both phenol and phenoxide ion ... So when you wash your hands, for example, the long, nonpolar hydrocarbon chain dissolves the oils on your skin. We recognize this as resonance and we recognize that it will lower the energy of a carboxylate ion compared to that of an alkoxide ion in which such resonance is not possible. More than two double bonds may have a cumulated structure, as we find in 1,2,3-butatriene (CH 2 =C=C=CH 2) and 1,2,3,4-pentatetraene (CH 2 =C=C=C=CH 2).The carbon atoms in such cumulenes all have a linear configuration, but the configuration of the terminal substituents depends on the number of cumulated double bonds. In each structure, draw all atoms, bonds, lone pairs of electrons, and formal charges. The basic catalyst hydroxide ion is regenerated. The phenoxide ion has resonance stabilization since the negative charge can be delocalised over 4 atoms (3 carbons and 1 oxygen), making it more stable. Carboxylate-Wikipedia Found inside – Page 105... pb represent the two resonant structures, (A) (B) For the neutral molecules and the alkoxide ions only one structure has been considered since resonance ... Better results are obtained if the alkyl halide is primary. It attacks the electrophilic carbonyl carbon atom of the unchanged second molecule to form an alkoxide ion. 2). The primary carbocation formed in the in the polarizing resonance structure of an aldehyde (discussed above) is less stable and therefore more reactive than the secondary carbocation formed by a ketone. This unexpected geometric arrangement can be explained by resonance (or conjugation). Acting as a nucleophile, the carbanion attacks the carboxyl carbon of a second molecule of ester. In the copper-catalyzed oxidation of alcohols to aldehydes, a Cu(II)-alkoxide (Cu(II)-OR) intermediate is believed to modulate the αC-H bond strength of the deprotonated substrate to facilitate the oxidation. Properties Types of amines. Found inside – Page 443(16-46) In an acidic medium, however, the alkoxide ion is converted into ... on the alkoxide oxygen as demonstrated by the stable resonance structure ... R—NH 2 —>R—NH – +H + R—O —H—>R— O – +H +. Only one resonance structure can be drawn for an alkoxide ion, but two structures can be drawn for a carboxylate ion, thus delocalization of charge is greater in carboxylate ion. There are three other resonance structures that can localize the charge in three different carbons of the ring. An α hydrogen on the ester is removed by a base, which leads to the formation of a carbanion that is resonance stabilized. Found inside – Page 339CI CI 8.14 We begin by drawing the resonance structures for this compound : 18 ... Then , in the second step of the mechanism , an alkoxide ion ( RO- ) ... Found inside – Page 645... structures are not equivalent, alkoxide ions do not show resonance. O CH|3 || CH3 -C-OH + HO– CHCH3 --→ Ethanoic acid Propan-2-ol O|| CH| 3 ... The carbanion attacks a second molecule of benzaldehyde. Zinc ions occupy half of the tetrahedral sites. the nucleophile, which is an enolate ion (Figure 2). 5. The alkoxide ion eliminates a proton from water to produce aldol. One base that works well is lithium diisopropyl amide, ... Don't include the Li ion. Each zinc ion is surrounded by four sulphide ions which are disposed towards the corner of regular tetrahedron. The carbanion is resonance‐stabilized. Phenoxide ion is more stable than ethoxide ion as phenoxide ion exists in resonance structure. In alkoxide ion, the negative charge is localised on oxygen while in phenoxide ion, the charge is delocalised. Found inside – Page 317Recall that , when a molecule or ion can be represented by several resonance structures , that molecule or ion is more ... acids because alkoxide ions - the ions formed when an alcohol gives off a proton - are not stabilized by resonance . Because the ether is symmetric -- it is two tetrahedral carbons attached to an oxygen -- either side could originate as the alkoxide and either side could originate as the alkyl halide. Phenols are more acidic than related alcohols. Found inside – Page 428Interpretation nature O H [Resonating cannonical ofacidic : OH +OH +OH O +OH ... + H + [Resonance structure of phenoxidei on] Both phenol and phenoxide ion ... a tetrahedral alcohol product. This is a deprotonation step where a hydroxide ion pulls off a proton from the alpha carbon (carbon adjacent to the carbonyl carbon) to yield a resonance-stabilized enolate. (b) All these structures are p-substituted phenols, so the substituent must be the controlling It is an ion with negative charge. Found inside – Page 428Interpretation nature O H [Resonating cannonical ofacidic : OH +OH +OH O +OH ... + H + [Resonance structure of phenoxidei on] Both phenol and phenoxide ion ... Draw the alkoxide ion that is formed in each of the following cases. Aldol Formation. Found inside – Page 195... OH , alkoxide and halide anions [1]. In a recent publication, we have demonstrated the potential use of the reactant ion 0 to probe the structure of ... In the copper-catalyzed oxidation of alcohols to aldehydes, a CuII-alkoxide (CuII–OR) intermediate is believed to modulate the αC–H bond strength of the deprotonated substrate to facilitate the oxidation. 2. ... Alkoxide ion is a leaving group in this reaction! Found inside – Page 85839 resonance structures for carboxylate ion an alkoxide ion spo hybridized carbon H H H | | | ..9 This carbon has no unhybridized H–C–G–C–9: p orbital. Found inside – Page 1290It is because the contributing structures of carboxylate anion are ... ( Eqn . 8.3 ) neither alcohol nor alkoxide ion are stabilised by resonance and hence ... Found insideThe negative charge on the phenoxide ion is delocalized by resonance. ... in an alkoxide ion. .9 Hf . These two Kekulé structures are equivalent These three ... The conjugate base of acetic acid is the acetate ion, a carboxylate ion. Found inside – Page 428Interpretation nature O H [Resonating cannonical ofacidic : OH +OH +OH O +OH ... + H + [Resonance structure of phenoxidei on] Both phenol and phenoxide ion ... When dissolved in water carboxylic acids react with bases to form ionic salt, for example: Thus, the alkyl halide should be derived from ethanol and the alkoxide ion from 3-methylpentan-2-ol. 1. In contrast, an alkoxide ion, once formed, would have a strong negative charge localized on its lone oxygen atom, which would strongly attract any nearby protons (indeed, alkoxides are very strong bases). The ammonium ion loses a proton to form an —NH 2 group. Resonance stabilization of the carboxylate ion. 3. Found inside – Page 217Thus equivalent resonating structures and dispersal of charge makes the carboxylate anion more ... alkoxide ions (RO −) are not stabilized by resonance. Indeed, we have seen in past chapters that amines react with electrophiles in several polar reactions (see for example the nucleophilic addition of amines in the formation of imines and enamines in Section 19.8). Also, it is an SN2 reaction. Found inside – Page 851A. Alcohols, due to solvation effects on thealkoxide ion. ... The oxonium ion is not a resonance structure and, moreover, it follows from the protonation of ... Similarly, ion is surrounded by four ions. 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