AUTHOR OF THIS BLOG

DR ANTHONY MELVIN CRASTO, WORLDDRUGTRACKER
Dec 222016
 

Abstract Image

The transposition of Sandmeyer chlorination from a batch to a safe continuous-flow process was investigated. Our initial approach was to develop a cascade method using flow chemistry which involved the generation of a diazonium salt and its quenching with copper chloride. To achieve this safe continuous process diazotation, a chemometric approach (Simplex method) was used and extrapolated to establish a fully continuous-flow method. The reaction scope was also examined via the synthesis of several (het)aryl chlorides. Validation and scale-up of the process were also performed. A higher productivity was obtained with increased safety.

 

Efficient Transposition of the Sandmeyer Reaction from Batch to Continuous Process

Institut de Chimie Organique et Analytique, Univ Orleans, UMR CNRS 7311, Rue de Chartres, BP 6759, 45067 CEDEX 2 Orléans, France
ISOCHEM, 4 Rue Marc Sangnier, BP 16729, 45300 Pithiviers, France
§ Institut de Combustion, Aérothermique, Réactivité, et Environnement (ICARE), 1c, Avenue de la Recherche Scientifique, 45071 CEDEX 2 Orléans, France
Org. Process Res. Dev., Article ASAP

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1H NMR (250 MHz, Chloroform-d) δ 7.65 (dd, J = 2.1, 0.6 Hz, 1H, Har), 7.42 (dd, J = 8.7, 0.6 Hz, 1H, Har), 7.32 (dd, J = 8.7, 2.0 Hz, 1H, Har).

2,5-Dichloro-1,3-benzoxazole (33)

The reaction was carried out as described in general procedure B using 2-Amino-5-chlorobenzoxazole (221 mg, 1.31 mmol). After purification with silica flash chromatography (EP 100%), the product was isolated as a yellow oil (62 mg, 25%).
CAS number 3621-81-6.
1H NMR (250 MHz, Chloroform-d) δ 7.65 (dd, J = 2.1, 0.6 Hz, 1H, Har), 7.42 (dd, J = 8.7, 0.6 Hz, 1H, Har), 7.32 (dd, J = 8.7, 2.0 Hz, 1H, Har).
str1
13C NMR (101 MHz, Chloroform-d) δ 152.27 (C), 150.12 (C), 142.06 (C), 130.79 (C), 125.85 (CH), 119.78 (CH), 111.16 (CH).
HRMS [M + H]+ (EI) calcd for C7H4Cl2NO: 187.9664, found: 187.9663.

1H NMR PREDICT

str1 str2

13 C NMR PREDICT

str1 str2

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