Synthesis of substituted 7,7,8,8-tetracyanoquinodimethanes

Abstract

Twenty-one 7,7,8,8-tetracyanoquinodimethanes substituted with Me, Et, i-Pr, F, CI, Br, I, OMe, OEt, 0-i-Pr, 0-i-Bu, O-i-C5H11, -O-CHzOCHr, SMe, and CN groups are reported along with several TCNQ dianion salts.T h e charge transfer complex between tetrathiofulvalene 3i, 3m, and 3n were prepared according to Scheme 11, startand tetracyanoquinodimethane (TTF-TCNQ) 1 shows high ing with p-xylenes 7 or terephthalic acids 8. T h e tere--. phthalic acids were converted first to their acid chlorides, then reduced to glycols, and treated with hydrogen halide [ c f # 3 I" [::m::] t o give p-xylylene dihalides. 1,4-Bis(bromomethyl)-2,5-dimetallic electrical conductivity from room temperature down t o -60 K.14 This chemistry has already been expanded by the preparation of selenium,' tetrathiomethoxy,8 dimethyl,2 t e t r a m e t h~l ,~ benzo,lOJ1 and tetrareported here of a rather complete series of substituted TCNQ's, extended TCNQ's, and related anion salts t h a t may aid in the systematic analysis of charge transfer salt conductivity.'* Substituted 7,7,8,8-tetracyanoquinodimethanes were synthesized according to procedures disclosed or claimed in Du P o n t patents.13 These syntheses most frequently startene dihalides 3b-g, 3j-1, and 3p-s were prepared by direct bischloromethylation of t h e appropriately substituted benzene, as shown in Scheme I. p-Xylylene dihalides, 3a, 3h, 4 ; t 4 * I/@1 c, C1, OMe, OEtb c, OMe, OEt* TCNQ(0Me )(OEt) d, OMe, 0-i-Pr' d, C1, OMe, 0-i-Pr'

Bound-Excited Electronic States of the Anion of 2,3,5,6-Tetrafluoro-7,7,8,8-tetracyanoquinodimethane

“…This system is of a great interest for material chemists because it plays the role of an electron acceptor in the formation of charge-transfer complexes. 19 The TCNQ-F4 -radical anion forms tight pairs in alkali metal salts such as [Na + /TCNQ-F4 -] or [K + /TCNQ-F4 -], even at room temperature. 20 In 1995 Sugimoto et al reported the first observation of weak ferromagnetism in purely organic radical solids such as [Li + /TCNQ-F4 -].…”

2,5-Bis(methylthio)-7,7',8,8'-tetracyanoquinodimethane

“…H13~ "~' 10 H14 BMT-TCNQ was prepared by a method analogous to the DuPont procedure in four steps starting from 1,4-bis(methylthio)benzene (Wheland & Martin, 1975). The dark brown powder was purified twice by vacuum sublimation using apparatus described previously (Mizuguchi, 1981).…”

A Novel One-pot Synthesis of Isothiocyanates and Cyanamides from Dithiocarbamate Salts Using Environmentally Benign Reagent Tetrapropylammonium Tribromide

“…37 However, this method involves the use of po-tassium or sodium cyanide and bromine for the preparation of cyanogen halide (which is again highly toxic), making the protocol environmentally unacceptable. Literature reports on various other methods for the preparation of cyanamide using different synthetic strategies, such as cyanation of amines using CN + equivalents as synthons, [38][39][40][41][42][43][44] Tiemann rearrangement of amidoximes, 45 coupling reactions involving Pd isocyanides, allyl carbonates and trimethylsilyl azide, 46 and sodium bis(trimethylsilyl)amide as deoxygenating or desulfurizing agents. 47 Yet another method for the preparation of cyanamides involves the reaction of hypervalent iodine(V) species with N,N 1 -disubstituted glycylamide.…”