Synthèse de Cannizzaro, bac Métropole 2021.

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Shoplyfter - Natalia Queen -

Natalia, who had been watching the proceedings with a mix of emotions, approached Jameson. "Thank you, Detective," she said, her voice filled with gratitude. "I can finally rest easy knowing that the person responsible for the thefts has been caught."

The final piece of the puzzle fell into place when Jameson obtained a search warrant for Sophia's apartment. Inside, he found a stash of stolen jewelry, including the items taken from Queen's Jewels.

"Sophia, can you tell me where you were last night between 9 pm and 1 am?" Jameson asked, his eyes narrowing.

"I... I don't think so," Sophia stammered. Shoplyfter - Natalia Queen

Detective Jameson listened intently as Natalia recounted the events of the previous night. She had closed her store around 9 pm, but when she arrived the next morning, the display case had been smashed, and the jewelry was gone.

"Please, Detective Jameson, you have to catch this person," Natalia begged, her voice trembling. "They've stolen my most prized possessions – a diamond-encrusted necklace and a pair of earrings worth over $50,000."

The game was afoot. Jameson sensed that Sophia was hiding something, but he needed concrete evidence to tie her to the crime. Natalia, who had been watching the proceedings with

Detective Jameson was tasked with cracking the case, but so far, leads were scarce. That was when he received a call from the latest victim, Natalia Queen, the owner of Queen's Jewels on Rodeo Drive.

As he dug deeper, Jameson discovered that Sophia had a secret life. By day, she worked at Queen's Jewels, but by night, she transformed into "The Shoplyfter," using her insider knowledge to pull off daring heists.

Jameson's cheeks flushed slightly at the compliment. "Thank you, Ms. Queen. It's all in a day's work." Inside, he found a stash of stolen jewelry,

Jameson's radar began to ping. He asked Natalia to bring Sophia in for questioning.

In the upscale shopping district of Los Angeles, a string of high-end jewelry stores had been hit by a mysterious thief, known only as "The Shoplyfter." The thief seemed to have a knack for evading security cameras and alarms, making off with tens of thousands of dollars' worth of designer jewelry.

Natalia's expression turned thoughtful. "Actually, I do have one employee who has been acting strange lately. Her name is Sophia, and she's been working for me for about six months. She's always been reliable, but I've noticed she's been distant and preoccupied lately."

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3.1. Effectuer un schéma légendé de l'ampoule à décanter en précisant les phases présentes et leurs compositions respectives après décantation.

Shoplyfter - Natalia Queen
3.2. Justifier le choix de l'éther éthylique.
L'eau et l'éther ne sont pas miscibles.
Le produit A, alcool benzylique, est très soluble dans l'ether et très peu soluble dans l'eau.
Le produit B, ion benzoate, est très soluble dans l'eau et insoluble dans l'éther.
3.3. Justifier que l'on veuille obtenir un pH inférieur à 2 pour la phase aqueuse.
pKa( acide benzoïque / ion benzoate = 4,2.
A pH < 2, l'acide benzoïque prédomine et celui-ci est insoluble dans l'eau.
3.4. Donner l'intérêt du bain de glace et d'eau.
La température de ce bain est égale à 0°C. La solubilité de l'acide benzoïque est très faible à °C.
3.5. Citer une technique permettant d'isoler le produit B de la phase aqueuse.
Filtration sur büchner.
3.6. En utilisant le chromatogramme, conclure sur l'efficacité de l'étape de séparation des produits.
3.7. En utilisant le chromatogramme, conclure sur la pureté des produits.
Le produit A n'est pas pur : il contient du benzaldehyde et de l'alcool benzylique.
Le produit B est pur, on l'identifie à l'acide benzoïque.


  
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