Browse Prior Art Database

Synthesis of 1,3,5-Triethynylbenzene (Teb) and 4,4'-Diethynyldiphenyl-Ether (Dedpe)

IP.com Disclosure Number: IPCOM000042130D
Original Publication Date: 1984-Mar-01
Included in the Prior Art Database: 2005-Feb-03
Document File: 2 page(s) / 38K

Publishing Venue

IBM

Related People

Dawson, DJ: AUTHOR [+2]

Abstract

The preparations of TEB and DEDPE each involve two steps - the first step involves Hagihara-modified Stephens-Castro coupling of the appropriate aromatic bromide (1a, 2a) with a protected acetylene such as 2-methyl-3-butyn-2-ol (R=C(CH3)2OH) with a palladium/copper co-catalyst (PdC12, CuI and PPh3 have been employed most often) in an amine solvent (usually triethylamine). The second step involves deprotection of the resultant adducts (1b, 2b) by a retrofavorskii reaction generating the free acetylenes (1c, 2c) and a ketone byproduct (acetone when R= C(CH3)2OH) which is removed as it is generated. A number of problems (1-4) arose when conventional synthetic techniques were employed which hampered straightforward large scale preparation.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 52% of the total text.

Page 1 of 2

Synthesis of 1,3,5-Triethynylbenzene (Teb) and 4,4'-Diethynyldiphenyl- Ether (Dedpe)

The preparations of TEB and DEDPE each involve two steps - the first step involves Hagihara-modified Stephens-Castro coupling of the appropriate aromatic bromide (1a, 2a) with a protected acetylene such as 2-methyl-3-butyn- 2-ol (R=C(CH3)2OH) with a palladium/copper co-catalyst (PdC12, CuI and PPh3 have been employed most often) in an amine solvent (usually triethylamine). The second step involves deprotection of the resultant adducts (1b, 2b) by a retrofavorskii reaction generating the free acetylenes (1c, 2c) and a ketone byproduct (acetone when R= C(CH3)2OH) which is removed as it is generated. A number of problems (1-4) arose when conventional synthetic techniques were employed which hampered straightforward large scale preparation. These problems and their solutions are as follows: 1) The intermediates 1b and 2b (R=C(CH3)2OH) were very crystalline which made their isolation and processing difficult. It has been found that a mixture of 2-methyl-3-butyn-2-ol (R-C(CH3)2OH and 3-methyl-1-pentyn-3-ol (R=C(CH3)(CH2CH3)OH) produces a mixture of isomers (four in the case of 1b, three in the case of 2b) which is far less prone to crystallization. This effect allows isolation of these intermediates by a simple filtration using much less solvent. 2) Earlier preparations utilized triethylamine as solvent (bp 89) and required >10 hours at reflux to go to completion using a reasonable (>1%) amount of catalyst. It has been found that dipropylamine is an excellent solvent for the reaction since it is higher boiling (bp 110^) and reactions typically go to completion in 1-3 hours using less (Z0....