"
Synthesis, Spectra, and Reactions of N- Tl·iphenylm.ethylpyridinium Salts.
Reaction of Triphenyhnethyl Chloride with Pyridine under High Pressure
YOSHIYUKI OKAMOTO· AND YASUO SHIMAKAWA
Research Divisian, Department of Chemical Engineering, New York University; University Heights, New York, New York
10458
Received January 80,1970
-
N-Triphenylmethyl- (trityl-) pyridinium chloride (I) was synthesized from trityl chloride and pyridine by
means of high pres;;ure (4000-5000 atm) in dioxane or pyridine solution at 60-70°. Compound I \VIIS found to
react rapidly with methanol and water to produce trityl methyl ether and triphellylcarbinol, re~r)('cl ively. \\,it h
moisture, it was converted into the molecular complex (II) of triphenylcarbinol ,md pyridinium chloride in the
solid state. The ir, UV, visible, and nmr spectra. of I were compared to those of N-lritylpyridilliulll perchlorate
and Buoroborate. The deshielding of pyridine ring proto ns of these N-tritylpyridinium compounds is mueh
smaller than that of other N-all.:ylpyridinium compounds. Explanation of this phenomenon is sll!!g;e~tcd ; Ntritylpyridinium bromide (III ) was synthesized from trityl bromide and pyridine without applyillg hi~h pressure. The differences between trityl chloride and bromide in the formation of N-tritylpyridiltiunt compuullli
are also discussed.
It has' long been known that the yellow color of the
trityl ion in nitromethane solutions of trityl chloride
discharged immed iately upon addition ot pyridine.
This phenomenon was attributed to the formation of
tritylpyridinium chloride (1).1 The solids "tritylpyriwllium chloride" reported in the litcmture~ were
• To wbom eorre. pondenee sbould be addres.ed .
(1) .\. Slreill\i~.,..,r. Jr .• "S<lh-olytic Oi_placement Reacli<ln ... · M cGraw-
Hill, Sew York, N. Y., 1962. p 82.
(2) Prenored from tril yl ch loride anrl pyrirline by J . F . Xurri. nnd L. R.
Cuh·er. Amer. CIt,III. J .. 29, 1 J~ ( 11.1\13). by E. V. Meye r ami 1'. Fischer, J .
Prak/. Chtm., (21.82, ,';23 (1010), by C ..\ . l\rBu. a ud H . Host'U, J. Alllfr.
Clotm . Soc., 47, 27·J.\ (192fi). It was al~o obtained from a p.n i ,lin • • " Iution
o f triphenvl""rlJlno l an.1 h},lro~e o rhl, ..
loy H. lIdf,·ril"i, lind Il. ]),·110.
B,r., a8 , 160:'\ (J 112:,); this prorlurt
.hown to contain t h .. ("Irments of
one molecule of waler by H. Itelferic h uud 11. Siehcr. ibId . • 69, tlOO (lOLU),
and Helferich'. conclusiono were tater conHrmed by E. D. Hugh •• , J. Chtm.
Soc., 75 (1933).
".,,<
"I.
shown to be a complex (II) of triph e ll~' lc:trhillol :.Ind
pyridillium chloriJ.c a:,;sociated throLl~h u W ':Ik h.\"drogCIl bUild in the solid stat , ..1
Generally, ill lIuc\('ophilic rC':lrtiollS ·the tit r01l1!:C'r
nucleophilic re;lgl'llt, p.H illillc. would hI' I XPI'('It'd to
react faster with alkyl halide · Ih:1I1 lIIelhanol. ~ However, the synthc 'is ot S-lril~' lpyri l lllti\t1l\ dtlllndc !rulll
t,rit yl rbloricll' :t lld pn·idi ltl' h~' I'~ 11\\"'1\ I io n:" pr",'p/bln's
was Ull ·llllCC::;:;ful, :dl huugh \tllder ,utlll:1r \"lItultl iUlts
m('(h:tllUl rcactl,,1 l"l':lIlilv wil II I ril~ rll l,I! id ,· III f" rm
trit~·l mcth~· l ethl'r.3 F:·tilurc to s.\·lllhe.,il.l' X -I ri l~ Ip."ridinium ch loride ma~' be att.rihu t I'll In it " tlllf:tvor:\hlc
.4,"".
(3) C. G . Swain aud Y. Okamoto. J .
Ch"n .•~or .• n , .1 I\lV I tlI7tJ).
(4) C. K . In ~otdt "StructuTo ami ~lt·(·h .nl i4m In C)r,(Rni ct (,hl'mi:(lry,"
Cornpll linivrr~i(\~ Prc .. --. h hn.cn. N. Y .. I O.i .J , p' ,l."i tL
N -TRIPHENYLME1'HYLPYRIDINIUl\{
J. Org. Chem., Vol. 35, No. 11, 1970 3753
SALTS
equilibrium or slow rate relative to methanol captive,
shown in eq 1.
9-
Q-{-Cl
+
6
9·
o- 0c-IIO-
CC
(1)
Reactions of alkyl halides with :l.Dunes to give a
quaternary ammonium salt have been extensively
studied with respect to steric effect between reactants
and the effects of pressure on rate and equilibrium.
The rate generally increa es 'w ith increasing applied
pressure. The equilibrium of eq I would be expected
to shift from left to right with increasing applied pressure on the system, due to decrease in volume on the
reaction." .
The present investigation was initia.lly undertaken
to attempt the synthesis of I from trityl chloride and
pyridine by means of high pressure. The properties of
I successfully obtained a re described.
Results and Discussion
Synthesis of N-Tritylpyridinium Chloride (1).-A
dioxane solution of trityl chloride and pyridine or a
Inixture of both components (the latter in large excess
ratio) was heated at 60-70°, for 10-15 hr under 40005000 atm pressure. The white solid I obtained was
separated by filtration and washed three times with
dried benzene. The crystals were dried in a desiccator
under vacuum. The microanalysis of the compound
fitted the molecumr formula C24H 20NCl. The melting
point wa 90-95 0 with some decomposition. However,
when the solid was exposed to the atmosphere, the
melting point gradually ro e and finally reached 176 0 •
The mixture melting point of the 176 compound with
the complex II of triphenylcarbinol and pyridinium
chloride did not show any depre sion. .F urthermore,
the 176 0 compowui was identified by ir spectrum as II.
The ir spectrum of alkyl chloride shows a C-Cl bending ab 'orption b:.md at 2 0-360 cm- 1 a well as its
symmetrical s tretching absorption in the region 500-600
cm- 1 anti au tl 'ymmetric ab 'orption peak in the region
600-700 em- I • G The stretching ab~orption bands arc
Hsu:111y difficult t-odistinl!:ui h from phenyl ring absorption " wherea ' the b ndin~ a.b 'orption band iti more reliable for iucnlitic:u:ion. The C-Cl bending ab:;orptioll
hand at :H."i ('1\1- 1 of tTit~'1 chloride wa not in the spectrum of 1 ill the so ·J. st:1t.e l:\ujul mull). However, the
~(Jcct rutn of an equimubr mi.."turc of trityl chloride and
0
(5) S. D . Uamann, ~rulrh Pressure Physic. and Cbematry," Vol. 2,
R . l'. Hrn,II\,. 1',1 , _\ I .. l_i~ Pn',,_. :-;,.\\ York. !\_ Y .. 1!1I1:1.
\tl) :-;. JJ. (;ollhll\>. " U. Uaty, amI F . .E. \\ iberl)" " JOLrotlucLioD to
lnfrared "OU Itamao e~t.roIlcopy." Academic Pre38 • .New Yuck, N. Y••
19tH.
pyridine in Nujol mull shows the C-CI bending absorption band. When I was treated with nn excess of
methanol nt l'oom temperature, trityl methyl ether and
pyridinium chloride were obtained. With water, I was
readily converted into triphenylcarbinol and pyridinium
chloride.
Properties of I in Solution.-Compound I was insoluble in benzene or carbon tetrachloride, but soluble in
chloroform, acetonitrile, and dimethyl sulfoxide. The
ultraviolet absorption peaks of I in dichloromethane
appeared at 234 mJ.L (E 5-100) and 257 (2500). The
latter peak is due to pyridinium ion. N-Tritylpyridinium perchlorate and fluorobomte were prepared from
the reactions of trityl perchlorate and fluoroborate with
pyridine without applying pre sure. The visible absorption spectrum of I as well as of tritylpyridinium
perchlorate and fluoroborate in dichloromethune was
recorded. However, adsorption in the region 400-450
mJ.L for the trityl ion was not observed.
The nmr spectrum of I was almost identical with
those of N-tritylpyridinium perchloride and fluoroborate. The pheliyl proton spectrum appeared at T 2.70
as a singlet.7
For comparison, the chemical shifts of the a-, {3-, and
'Y-pyridine ring protons for other pyridinium compounds
are summarized in Table l,9 The ubstantial de shielding of the pyridine rinrr protons in the pyridinium compounds are due to the decrease in electron churge density at the individual carbon nuclei as a result of the
fomlation of the positively charged nitrogen. 1o The
(7) Recently, the recharacterizatioo of "hexaphenyletba ne" produced
by the dimerization of triphenylmethyl radical was reported by Lankamp.
Nauta, and MacLean.' The J-diphenylmethylene-4-trityl-2,5-cyclohexadiene 'structure was proposed for the dimerizatioo product. Accordibgly,
the question might arise for the structure of 1; in.tead of I, the pyridine
may attack at the para position of phenyl and form l-diphenylmethylene-2,5-
(U
Yo<
o
D
IV
cyclohexadieoe 4-pyridinium chloride (lV). Howe"er, the nmr spectra of I
shows that tbe phenyl protons were a.,.inglet (r 2.70). The absorptioo.
correspoodiog to the olefinio protoD' (r 3.6-1.2) and aliphatic proton (.r
-5) were not obsen·ed. Moreover, the proton ratio of phenyl. and pyridine
were approximately 3: 1.
(8) H . Lankamp, W. Th. Nauta, aod C. MacLean, Tetrahedron LeU.,
249 (1068).
(9) The chemical shifts of the pyridine ring protons in pyridinium salt8
were "examined in ,-arlou:J oouucolratioDd o( CnCI.. The concent.rations
Concentration (w/ v%) value
_ _ _5"7 - - "
/
pyridinium
ohlonde
Pyridinium
bromide
Pyridinium
chloride
Pyrid.n,ulll
bromide
.
IJ
'Y
..
{J
'Y
0 . 96
1.88
I. 42
0 . 93
1.83
1.39
1. 71
1. 27
----IO %~
0
0
0 . 87
1.75
1.37
_ _ _ 15 '70 --~
0 . 8\
,---20 % --~
..
~
'Y
..
{J
'Y
0.89
1.75
1.30
0 . 89
1.74
1. 29
0.79
1.69
1. 21
0 . 1l0
1. 69
1.22
dl'-Jl('ndent o n the flhihs are auout within
mUK"!'
T ±O.l o\"(·r. th.';ie concentration
The nUle iu raul" 1, 11, ~I1U 111 W~rtl llluu,gUrtJJ In U. l--o.L Jl !!Iulu-
won . ,
(10) 1. C.
Smi~h
aDd W. O. Schoeider, Can. J. Ch.rn.,
n , 1158 (1001).
3754 J. Org. Chern., Vol. 35, No. 11, 1970
OKAMOTO AND SHIMAKA WA
TABLE
I
CHEMICAL SHIFTS OF PYRIDINE RrNG PROTONS OF THE PYRIDINIUM DERIVATIVES ( .. VALUES)"
.
,...---~CDCh
Compd
Pyridine
Pyridinium chloride
N-Methylpyridinium iodide
N-Benzylpyridinium chloride
N-Benzhydrylpyridinium
chloride
N-Tritylpyridinium
chlorige (I)
.
N-Tritylpyridinium
brornide (III)
N- Tritylpyridinium
perchlorate
N-Tritylpyridinium
fluoroborate
1. 56
0.98
1 . 08
0
{J
(0)
(0.58)
(0.48)
(1.56)
2.90
1.88
1.80
1.80
..
solution-- - - - - , ,...----CH,CN solution---~ ,----DMSO-d. solution----..
lJ.{J
"y
lJ.a
fJ
lJ.{J
"y
lJ."y
"y
~
..
h
{J
M
2.50 (0)
1. 44 (0)
(0)
2 . 66 (0)
2.34 (0)
1.34 (0)
2.65 (0)
2 . 28 (0)
(1.02)
1.44 (1.06) 1.16 (0.28) 1.94 (0.72)
1.44 (0.90) 0 . 90 .(0.44) 1.75 (0.00) 1.25 (1:03)
(l.IO)
1. 40 (1.10)
(1.10) . 1. 50 (1. 00) 0.24 (l. 20) 1.88 (0 . 78)
1.54 (0.80)
0 . 66 (1:00) 1.84 (1.06)
1.40 (1.10)
1.36 (0.20) 2.44 (0.46)
2 . 04 (0.46) 1.40 (0.04) 2.50 (0.11)<
1.32 (0.24) 2.46 (0 . 44)<
2 . 24 (0.26)
0.88 (0.46) 1.72 (0.93) 1.25 (1.03)
1.30 (0.14) 2 .44 (0.22)<
2 . 18 (0.16) 1.30 (0.04) 2 . 42 (0.23) 2.08 (0.20)
2.06 (0.28) 1.30 (0 .04) 2 : 38 (0.27) 2.00 (0 . 28)
1.25 (0 . 09) 2.35 (0.,\0) 1.92 (0.36)
.. All chemical shifts referred to tetramethylsilane as internal standard. b These values indicate applied shifts from the corresponding
pyridine ring protons. c Peaks are partially overlapped with the phenyl proton absorption.
deshielding of the {3- .and ,,(-pyridine ring protons in
benzyl and benzhydryl pyridillium chlorides is similar
to that of N-methylpyridinium iodide and pyridinium
chloride. On the other hand, the deshielding of the apyridine ring protons is quite varied. This may be due
to the effect of counterions l l (ion pair formation) or to
the shielding by the adjacent phenyl group.12 From
Table I, it is clear that the deshielding of the fJ- and "(pyridine ring protons of N-tritylpyridinium compounds
is much smaller as compared to that in other pyridinium compounds. A similar trend is also observed
in the chemical shifts of the methyl protons of the "(picolinitlm compounds; i.e., the chemical shift of the
methyl group of N-trityl-"(-picolinium perchlorate
appears in between those of "(-picoline and ,,(:'picolinium
chloride (Table II). The exact explanation of this
TABLE
II
CHEMICAL SHIFTS OF 'Y-PICOLINE RING PROTONS AND
-y-METHYL PROTONS OF THE N-'Y-PICOLDIIUM ( T VALUES)
Compd
'Y-Picoline
..
1. 50
DMSO-D. solution
(J
(0)
2.80
.
lJ.(J
(0)
"Y-CH,
7 . 70
lJ.b
(0)
N-'Y-Pic:olinium
1.00 (0.50) 1.90 (0.90) 7.28 (0 . 42)
chloride
N-Trityl-'Ypicolinium
perchlorate 1.40 (0.10) 2 . 55 ' (0 .25) ' 7 .56 (0 . 14)
• These values indicate applied shifts from the conesponding
pyridine ring protons. b These values indicate shifts from the
. methyl protons of 'Y-picoline.
phenomenon is not clear. However, this may be
. attributed to the following: The coordination bond
between the carbon and nitrogen in N-tritylpyridinium
compound;:; 'is stretched in order to minimize the steric
strain between phenyl groups and pyri(line. This may
al 0 be enhanced by :1. g:1.in in reSOlU.l1Ce energy of t hree
phenyls in th~ parti3.11y developed trit ~' l ion. Thus, the
resulting electron charge density on the nitrogen atom is
not as low as those of N-bellz~'l a nd X-benzylhydryl
pyriciillium chloride;:;. COli:; ,q uent.ly, t he de ' tticlwng
efTect of t he p:nidillc ring prot ons in I i:; not a:; pro-:noullccll as tllo:;e ill the other py ridi rliulU compounds.
It ca n :11"0 be a ttributed to ion-pai r fo nn:l t ion. The
pyridinium ion p:1.ir · with countc'riolls such us chloride
or iodide in acetonitrilo or nitrobenzene. The count·er(11) G. K otowycl.• T. Shaffer, and E. B ock. Ca n . J . CII . ". .• 42, 2541
(1964) .
(12) D. G. Farnum, J. Am.... CAt",. Soc .• a., 93" ( l!lIH).
ion is most p·r obably situated close to the positively
charged nitrogen,13 and thus reduces considerably the
1r-electron polarization calculated for an isolated pyridinium ion. 14 Thus, when the bulky group is bonded
to the a position or on the nitrogen atom of pyridine,
the counterion may not be as close to the positive nitrogen and may be situated near the electron deficient and
less sterically hindered {3 and 'Y positions of the pyridine.
As a result, the low field shifts of the {3 and · "( prot()llS
in N -tritylpyridinium compounds are found to be
smaller than those of other pyridinium compounds cited
in Table 1. 15
A similar phenomenon was observed in the chemical
shift of a-substituted pyridinium compounds (Table III).
The magnitude of the low field chemical shift (",1 ppm)
. of the {3- and "(-pyridine ring protons of 2,G-lutidinium
compounds is similar to those in pyridinium or Nmethylpyridinium halides. However, the low field
. chemical shifts of the fJ- and "(-pyridine ring protons in
2,6-di-tert-butyl-N-pyridinium iodide are not as large
as those of less sterically hindered pyridinium compounds; This may also be attributed to the countcrion
association close to the electron deficient fJ and "(
positions of the pyridinium and to the reduced polarity
of C-H bonds.
The nmr spectrum of I did not change after the
chloroform solution was allowed to stand for 10 days at
room temperature. However, when I was dissolved in
chloroform at room temperature and then the solvent
was removed under vacuum, trityl chloride was isobted
instead of I. These results indicate that, as the solvent
is removed, the chloride ion reacts with the trityl moiety
to form trityl chloride and pyridine.
R ecently , syntheses of N- tritylpyridinium bromide
(IID from tri tyl bromide and pyrilliue in acctollitrilc 17
(13) C. R erat, Act« C ry,ta/loqr .• UI, 427 (1!l6!!)'
(14) G . Ii: otowyc •. T. Shaefer. and E . Bock. Cun. J. Ch em .• U , 25.11
(19G4 J.
(15) T he st ructure of trit ylp,' ri, linium L1lIlY he .i lllil3r to tha t of tetrapheny lmethane of wbic lt p henyl grlJ IlI)S are lWl :t l eli Lo ea.ch other (;'15° anp;le
bet ween, t.he ring a nu t ile ,"cruea I p h..t.fll';i) ," T hi:; u ni \ \u,~ CQ Uh J(Hratiou Ull1y
be etTdcted to sl,ie lJ (--0 ..; ppm) th " p. lIt1 d ~-py ri di il e rin lt I'ToLon. hy the
udjl\.,·t'lit plJcn~ I ring t.'u rn' ol.
Il o\\l'\'cr, l he- }Jllt' ny l [lll ~ I,r\'lu ll'; vf It'l raphenylme th!1 06 a re a LJsorheu a t. l' 2.70 (o.s a singl('l) whi c h i!4 nol diffe rent
rrom thA pht>nyl rinJ,C prl)flln absorption (T :!. 7lH (~f tril.v l ch illridt· in t ' I )CI • .
( I C)l A . 1. K ILaij(orudskii " OrJi:Rnic Che m ica l "rY3Ulllo!l mp hy,"' COli. ulI" nl" DurC3U . :\ e l\" Y nrk. ~. Y . • I !l til.lJ-t(J.!.
.
(Ii ) R . Unmi co and Co O. Brol\dlus. J. Or(/ . Ch f m .• 31, I fo07 (J91i6) .
U a £11 I l'o' :\oJ Hr,-mdl u:4 rep t. n t lit..' cilt.' ll1 ica l s hi£t!j ui t hu u- , ,;-, ;HHI ,), -Pl ndi no
ri ng prnt.on!4 of Ill,,, rltlo roform , nOl l o .t~t . n whic h !\ rl' il11th\r to th ~I:,t(, vi
py ritliniulll aat L. JIu \\'t)\, er, W6 could nul rt."proJuco the:tc JUUl ADd obtlLillcuJ
the vBlue. cit e<l in Tablo 1.
"
., N -TRIPHENYLMETHYLPYRIDINWM
J. Org. Chem., Vol. 35, No. 11, 1970 3755
SALTS
TABLE
CHEMICAL
SHIF'TS OP (3-
III
AND "Y-RING PROTONS OF a-SUBS'l'ITUTED PYRIDIN E D ERIVATIVES (T VALUES)
DMSO-d. solution
Compd
Registry no.
fJ
2,6-Dimethylpyridine
708-48-5
24994-62-5
2,6-Diroelhyl-N-pyridinium iodide
2,6-Dimethyl-N-methylpyridinium iodide
2525-19-1
2,6-Di-tert-butylpyridine
585-4S-8
26154-14-3
2,6-Di-lert-butyl-N-pyridinium iodide
co The~ value.s indicate shifts from the corresponding pyridine ring protons.
3 . 00
2.18
2.06
2 .85
2.40
.,.
(11.,.)"
2 . 44
1.66
1.60
2.38
2 . 00
(0)
(0 .78)
(0.84)
(0)
(0 . 38)
(l1fJ) 0
0)
(0 . 82)
(0 . 94)
(0)
(0.45)
grating spectrophotometer with cesium iodide cell was used.
and in acetone-dimethyl sulfoxide l8 ,I9 were reported.
Ultraviolet and visible spectra were measured with e. PerkinIII was readily synthe ized at room temperature,
Elmer Model 202 spectrophotometer.
whereas under simibr conditions or under more drastic
Trityl Fluoroborate and Perchlorate.-These compounds were
condition , the preparation of I was not successfu l \"ithprepared by the method previollsly reported. 23 Trityl fiuoroborate and perchlorate meited at 198° dec and 142°, respectively.
out applying high pressure. The ir spectrum of III in
N~Benzyl- and N-Benzhydrylpyridinium Chloride.-The e
Nujol mull was almost identical with that of I. Furpyridinium compounds were prepared from benzyl chloride and
thermore, the pyridine ring protons of III have similar
benzhydryl chloride with excess pyridi ne by refill'cing. The
deshielding effects to 'those observed in other tritylpyproducts were recrystallized from chloroform-benzene solution.
ridinium salts (Table I). These results show that trityl ..' Benzylpyridinium chloride (hygroscopic)2t and benzhydrylpyridinium chloride:'; melted at 12.:iand 207 re pectively.
bromide :lnd pyridine react in the solvents such as aceReaction of Trityl Chloride with Pyridine by High Pressure.tonitrile to form HI. \Vhen the solvent was removed,
The reactions of trityl chloride with pyridine under high pre_' ure
III was recovered, unlike the case of I , which dissociated
were carried out in either dioxane or pyridine as olvent. Trityl
into trityl chloride and pyridine. These remarkably
chloride (1.15 g) and pyridine (2.20 g) were dissolved in 5 ml of
dioxane ill a drybox. The high pressure technique described
different results may be due to the differences of reacearlier was followed. 26
tivity of Br- and CI-. In general, Br- is a stronger
N-Tritylpyridinium Chloride (I).-A dioxane olution of trityl
nucleophilic reagent than Cl-. However in aprotic
chloride and pyridine was heated at 60-70° for 10-15 hr under
solvents, CI- is more reactive than Br-. 2O,~1 Thus, the . 5500-6000 atm. After t.he die had cooled, the pressure was
above res ult may be accounted for by the sequence of
released to 1 atm. The capsule WIl>! opened in a drybox. The
white crystals obtained (60-70% yield) were separated by filtra(i) nucleophilicity and (ii) the size of ions'. The lurger
tion from the dark red olution and washed three times with dry
and les . reactive ion, Br-, does not react with the trityl
benzene. 'The crystals were dried in a desiccator under vacuum,
moiety of III, upon solvent removal. As n. result., III
mp 90-95° dec.
was synthesized by eva.poration of solvents from the
Anal. CalcdforC"HzoNC: C, 0.55; H •.') ..'i8; N.3.92; CI.
mi.xture of trityl bromide and pyridine in polar solvents.
10.00. Found: C, 0.40; H,5.80; N,3.85; Cl,9.71.
The melting point of I was determined in an open-ended Pyrex
This explanation is further supported bv the following
capillary tube . After 4 h]' from the tirst measurement, t.he
result: When III was mixed with pyridinium chloride
melting point of the compound had risen to 160-169 and it
in acetollitrile at room temperature and the solvent rereached 175-176° a few days later. When I was exposed to the
moved to dryness, the solid obtained was treated with
atmosphere, it was converted rapidly into the high melting compound . .
petroleum ether. After the petroleum ether was evapReactions of N-Tritylpyridipium Chloride with Water and
orated, trityl chloride \Va obtained in good yield ( ' 0%).
Methanol.-I (0. 1 g) was dissolved in chloroform and the solution
This result shows that, as solvent wus evaporated, CIwas t,reated with water at room temperat ure for 10 min. The
readily reacts with the trityl moiety of III to form
chloroform solution '1':\,<; 'epamted and dried over Drierite.
trityl chloride and pyridine.
Upon evaporating the chloroform, white crystals (0.07 g) were
obtained a.nd recrystallized from ethanol . mp lUoo, undepressed
The reactions of trityl chloride with 2 6-lutidinowere
0
,
0
attempted under high pres ure (up to 6000 atm) .
However no reaction was detected and trity 1 chloride
was recovered. quuntitatively_
Experimental Section
Solvents.and Reagents.-All solven t .. were dried over nr ierite
:llsd di~lill d. Pyridille. l -pil'I)line, alld :!,G-Iutidille (}:"~l1l\:I 11
K odak 0. ) ~ re uriI'd over calcium hyuriJe und distiJll'u. Trit)1 ('hh)riue ~K aud K Laburatories. lllc. ) W :l:, twice recrplalliled
ft III h!I1;.t'I~ PCI io CUIU Cl uel' \ItU :ltctyl .:hluritlc, 111(1 111112 0 . '~ Tri Iwndl'll.rbinol ! E:l:>tmnn l\otlak Co. ) was retn'~l:I llizeJ f f(11ll e! iUmui, In,, Hi I " .
instrumental Analyses.-Xmr ~pectr!l were obtailled I'll \
Variall AliI! ill':'trum nt. :\ P.e.kin-.Elmer :\[ odel :?;~7 illfr:1.red
~pe , · troph.)wmeter c IlIiPllt'd \\'lth ,",odillm .. hlunde OpllC~ W:I.'<
1I'l'd f"r ir !T!1'l\.'II!'('m~nl~ in tlw \,:\v" \.'tlgr h n 'giolt -I!lIII~:-lJfl
,'m - '. Fur the i Ir-illir:lrcJ r"~\oIl , a. 1'l'I'Kill- Diller .\I '/llo'l Ii:: 1
. (IS) G. Bn" lei>, .iJljl...,. Ch.m .• Int . Ed. l.·n.JI.. :I. ;)45 (19631.
( t 0) P.·n.i'UIl ~ ('VClIL1U o it"3.t tun wu.it l'roll~~or G. I'rh.'¥ld:t.
(20) . Wu~"'io, L. (;. :;;>""uotJ. S. Sm,~h. l. D. H: Ste"ens, lind J. S.
~:l.!1. J .ztt.;.f,l ..Ht ~.--;: •• 9. _ ~ d~H.H .
(21) W . .\1. W,,"ver 80(1 J . D . Hm~bi,oo. J . Am.,. Uh".,.. Soc., 86 . ~til
(lUtH).
(22) C. G. _ ...tn aDd E. E.
reg".,.. ibid .. 80.
I:! \ IIlSS).
by Mmixture with triphl'lIylearbinoI.
1 (0.1 g ) W:1S treated with 3 Illl of methanol for 5 min at room
temperature. The solid material was i~olated and wa hed with
methanol, mp 82°. no depression on mixing with pure trityl
II).ethyl ether, mp 84 °, prepared from It methanol solution of
trityl chloride and pyridine. The triphenylcarbinol and tricyl
mel hyl 1:'1 her i"olatl'd werc abo iden! ified by infrared spectroscopic .. tud~·.
S -Tritylpyridinium Perchlorate and Tetrafluoroborate. Tl'ityl
perl'hlnm,,} (:?tl ~) W:l.' di""ol\'l'u III III fill of :1.cctoni rrile ( 'I:'llow
>flhllion). Pyridinc (J Ill!) \\ ;1'; addl'd 10 thl' :l('clOnilrilf' , olut iP" tn I!i\'e :l rtll .. rk' ~ "lilt II illn . .\ftf·r r h(' ""III t iOIl W :I ~ 11I11.\\'(,d
to "tan;l a t rUIIIl1 (('!lIIlI'ratllt'<· f,>!' 10 mill , Ihe l-lli \'f"n L W:l" renlnvt'cl ill me'lv 1£1 J.!;ivt' t hi' Yl·liow ,.,.>lid. Tit!' ~oli tl W;\,; \\':I"ltl'd
wilh h{,IIZI'II!' thn'., tinll'~ alit! dril'r\ \ltllkr V ;\I·IIIIII1. Thf"n' wai<
llhu!tlt'J Ull ",:!' ; YlelJ oi X- \rt\ yipy ridill iu lIl pcrch loruu;. IIIp :!l~J­
:;1~ " .1('1 ",
.Y-Tri t ~ Ipyrid illiutll t(·tr:tllllil!'o[;oT:l" '\ !L~ prt'l'!ll't'd frl'1ll a
n~i.'.ire tf
,llltil.}tl ~,f ';;f\l t~'tra flll \r 1'.I··!tl~ .lt~ 1 pvr:li:.{· ill
!ll't'lunitrilll illlhe>'allli) way',." lile pcrchl,lr:Ut:. II1p l.i.-,_I.-,I u •
Z'l' If. J. [la"l'en, .Ir., l.. fl . 1!"llnH, lind K .• I. them "l\. J. Orl/. Cn' nt.,
ttl , !-I I:! 11 :,60 ).
,. \, ( •. ,\.hll\:'r"lm . Jr. ;\.nt l (~ .l t'r"f'lb 11.~'wr, I',:" '::3 , I til'.) tin'" .
;.:.~., ,; . 1' , ~I .. h~v, J . / (U'f<f. ~/1lJ'f. CIa,.m., 60. ,y.!:; ( H' ::~); (' ~" ," . A {,,,,t,. ,, 23 ,
I :l.iU l l!l~~ll.
1:!6) Y . OkalUuto aDd It. Shimizu, J. Amer. Ch"". Suc .. 90, 11 14:; t11111",
~
3756 J. Org. ekem., Vol. 35, No. 11, 1970
Trityl Bromide.-Trityl bromide was prepared by the method
previously rcported.1'I The colorless solid melted at 145-147°.
N-Tritylpyridinium Bromide. The solution of :1.2 g (0.016
mol) of trityl bromide and 7.l.g (0.09 mol) of pyridine in 50 ml
of acetonitrile was stirred for 24 hr and then the solvent and
excess pyridine were removed under vacuum. After washing
with pentane, a ~lightly tnn solid was recovered in 40% yield,
mp 137-139° dec (lit. 2r mp 139 0 dec).
Reaction of N-Tritylpyridiniwn Bromide with Pyridinium
Chloride.-The mh:ture of solution of 2.00 g (0.00f> mol) of Ntritylpyridinium bromide and 1.50 g (0.013 mol) of pyridinium
chloride in 50 ml of dry acetonitrile was stirred at room temperature for 10 min and the ' olvent was evaporated under reduced
pressure. The residue was extracted with 50 ml of dry petroleum
ether and then the solvent was removed under reduced pressure.
The white solid, recovered in 0% yield, melted at 111-112°
and proved to be trityl chloride by mixture melting point measurement and infrared spectro copy .
a-Substituted Pyridinium Compounds.-2,6-Dimethyl-N-pyridinium iodide was obtained by passing dry hydrogen iodide
into the benzene solution of 2,6-dimethyJp-yridine, mp 1 5°.
2,6-Dimethyl-N-methylpyridinium iodide was synthesized
from 2,6-dimethyJpyridine with methyl iodide by refluxing.
The product was recrystallized from ethanol, mp 239-240° .
•
f
(27) W. E. Backmann, "Organic Synthes8l," Coli. Vol. 3, Wiley, New
York, N. Y., p 841.
GlmiANINI AND LERCKER
Anal. Calcd for C8 RI2NI: C, 38.6; H, 4.82; N, 5.63; I,
51.0. Found: C,3.4; H,4.83; N, 5.77; I,51.1.
2,6-Di-tert-butylpyridine was prepared by lhe method of
Brown and Kallner,28 bp 61-62° (1 mm), the chloroaurate, mp
188 0 (lit.28 184.5°).
Anal. Calcd for C IIII'2NAuCI.: C, 29.4; H, 4.11}; CI,'
26.7; N,2.64. l"ound: C,29.9; II,4.29; CI,26.4; N,3.08.
2,6-Di-tert-butyl-N-pyridinium iodide was synthe' ized by
passing dry hydrogen iodide into the benzene solution of 2,6di-tert-butylpyridinc, mp 196-197°.
Registry No.-Triphenylmethyl chloride, 76-83-5;
pyridine, 110-86-1; I, 26156- 2-1; I perchlorn.te,
26156-83-2; I fluoroborate, 26156-84-3; pyridinium
chloride, 62 -13-7; N-methylpyridinium iodide, 93073-4; N-benzylpyridinium chloride, 2876-13-3; Nbenzhydrylpyridinium chloride, 26156- 8-7;
III,
7206-97-5; 'Y-picoiine, 10 - 9-4; N-'Y-picolinium chloride, 14401-93-5; N-trityl-"y-picolinium perchlorate,
26154-09-6.
Acknowledgment.-The authors gratefully acknowledge numerous stimulating discussions with Professor
C. G. Swain. (28) H. C. Brown and B. Kanner, J. AmtT. Ch.m. Soc.,
sa, 986 (1966).
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