Skip to main content
Ch. 20 - Enolates: Carbonyl Addition and Substitution
Mullins - Organic Chemistry: A Learner Centered Approach 1st Edition
Mullins1st EditionOrganic Chemistry: A Learner Centered ApproachISBN: 9780137566471Non è quello che usi tu?Cambia libro di testo
Tutti i libri di testoMullins 1st EditionCh. 20 - Enolates: Carbonyl Addition and SubstitutionProblema 18b
Capitolo 19, Problema 18b

Specify which in each pair is the harder Lewis acid. Justify your choice beyond just looking at Table 20.2.
(b) Li+ vs. Na+

Guida verificata passo dopo passo
1
Step 1: Recall the definition of a Lewis acid. A Lewis acid is a species that can accept an electron pair. Hard Lewis acids are typically small, highly charged, and have low polarizability.
Step 2: Compare the two ions, Li+ and Na+. Both are alkali metal cations, but they differ in size and charge density. Li+ is smaller in size compared to Na+, which means it has a higher charge density.
Step 3: Higher charge density makes Li+ a stronger Lewis acid because it can attract electron pairs more effectively due to its concentrated positive charge.
Step 4: Consider polarizability. Li+ is less polarizable than Na+ because of its smaller size and tighter electron cloud. This characteristic aligns with the properties of hard acids, making Li+ harder than Na+.
Step 5: Justify the choice using the table provided. Both Li+ and Na+ are listed under hard acids, but Li+ is harder due to its smaller ionic radius and higher charge density, which are key factors in determining the hardness of a Lewis acid.

Risposta video verificata per un problema simile:

Questa soluzione video è stata consigliata dai nostri tutor come utile per risolvere questo problema.

Concetti chiave

Ecco i concetti essenziali che devi comprendere per rispondere correttamente alla domanda.

Lewis Acids and Bases

Lewis acids are species that can accept an electron pair, while Lewis bases are those that can donate an electron pair. This concept is fundamental in understanding acid-base reactions in organic chemistry, as it expands the definition beyond protons (Brønsted acids) to include a wider range of chemical interactions. The strength of a Lewis acid is often determined by its ability to stabilize the negative charge of the electron pair it accepts.
Video consigliato:
02:49
The Lewis definition of acids and bases.

Hard and Soft Acids and Bases (HSAB) Theory

The HSAB theory categorizes acids and bases as 'hard' or 'soft' based on their charge density and polarizability. Hard acids, like Li<sup>+</sup>, have small size and high charge density, making them less polarizable and more stable in reactions with hard bases. In contrast, soft acids, such as Na<sup>+</sup>, are larger and more polarizable, favoring interactions with soft bases. This classification helps predict the stability and reactivity of acid-base pairs.
Video consigliato:
02:49
The Lewis definition of acids and bases.

Comparative Strength of Lewis Acids

To determine which Lewis acid is stronger between two candidates, one must consider factors such as charge density, size, and the ability to stabilize the resulting complex. In the case of Li<sup>+</sup> versus Na<sup>+</sup>, Li<sup>+</sup> is a harder acid due to its smaller ionic radius and higher charge density, making it more effective at accepting electron pairs compared to the larger, softer Na<sup>+</sup>. This comparative analysis is crucial for understanding their reactivity in various chemical environments.
Video consigliato:
02:41
Comparing hydrocarbon acidity
Pratica correlata
Domanda del libro di testo

Specify which in each pair is the harder Lewis acid. Justify your choice beyond just looking at Table 20.2.

(a) Al3+ vs. B3+

1139
views
Domanda del libro di testo

Rank the reactivity of the following carbonyls with nucleophiles, from least reactive to most reactive.

1153
views
Domanda del libro di testo

LDA can be used to form enolates on esters and nitriles. Predict the product of these alkylation reactions.

(a)

469
views
Domanda del libro di testo

Specify which in each pair is the harder Lewis acid. Justify your choice beyond just looking at Table 20.2.

(c) Mg2+ vs. Na+

723
views
Domanda del libro di testo

Specify which in each pair is the harder Lewis base. Justify your choice beyond just looking at Table 20.2.

(c) I- vs. F-

790
views
Domanda del libro di testo

Specify which in each pair is the harder Lewis base. Justify your choice beyond just looking at Table 20.2.

(b)

1187
views