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Synthesis of N Aryl 3 Hydroxy 2 Naphthamides

IP.com Disclosure Number: IPCOM000089215D
Original Publication Date: 1977-Oct-01
Included in the Prior Art Database: 2005-Mar-04
Document File: 2 page(s) / 51K

Publishing Venue

IBM

Related People

Heil, WP: AUTHOR [+2]

Abstract

Preparation of N-aryl-3-hydroxy-2-naphthamides, the general formula being shown in Fig. 1, by conventional ester-amide interchange reactions is unsatisfactory due to long reaction times and low yields.

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Synthesis of N Aryl 3 Hydroxy 2 Naphthamides

Preparation of N-aryl-3-hydroxy-2-naphthamides, the general formula being shown in Fig. 1, by conventional ester-amide interchange reactions is unsatisfactory due to long reaction times and low yields.

An alternate possible route to the N-aryl-3-hydroxy-2-naphthamides would proceed via 3-hydroxy-2-naphthoyl chloride, the formula being shown in Fig. 2, but common methods for preparing carboxylic acid chlorides are not applicable in this case.

A carboxylic acid chloride would generally be made from the carboxylic acid, but the acid precursor to 3-hydroxy-2-naphthoyl chloride is highly unreactive due to the presence of the ortho-hydroxy group.

The present approach in one embodiment provides a general preparation of N-aryl-3-hydroxy-2-naphthamides via the carboxylic acid chloride, as shown in Fig. 3. Step 1. 3-hydroxy-2-naphthoic acid is converted to the sodium salt using sodium hydroxide in methanol. Step 2. After removal of methanol, the sodium salt is converted to the carboxylic acid chloride using oxalyl chloride and pyridine catalyst. Step 3. The carboxylic acid chloride is then reacted in toluene with the appropriately substituted amine; or if the amine is insoluble in toluene, the reaction takes place in pyridine.

Neither the sodium naphthoate nor the naphthoyl chloride is isolated. Methanol (Step 1) and excess oxalyl chloride (Step 2) are each removed by azeotropic distillation with toluene. The amide produced in Step 3 is extracted from the reaction mixture with aqueous base and isolated by...