Synthesis of sulphides and sulphoxides by the action of thionyl chloride on mixed organomagnesium compounds

SYNTHESIS OF SULPHIDES AND SULPHOXIDES BY THE ACTION OF THIONYL CHLORIDE ON MIXED ORGANOMAGNESIUM COMPOUNDS* N. P. VOLYNSKII, G. D. GAL'PERN and V. V. SMOLYANINOV Institute of Petroleum-Chemical Synthesis, U.S.S.R. Aea~temy of Sciences (Received 21 Jul,e 1961)

IN connection with the investigation of the sulphur compounds of the middle fractions of petroleum, the necessity arose to obtain a series of sulphides and sulphoxides containing a cyclohexane ring and, in ])articular, dicyclohexyl sulphoxide. In the majority of cases, sulphoxides are synthesised by the oxidation of sulphides with the stoichiometric amount of hydrogen peroxide, chromic anhydride, or other suitable oxidising agent under appropriate conditions. Sulphides containing a cyclohexyl group are obtained by alkylating eyclohexanethiol ill an alkaline medium [11]: C6H~tSH@RHal

KOH

• C6[-[llSR

(l)

or by a photochemical method from cyclohexane and a mercaptan; the reaction takes place when a mixture of equimolecular amounts of the reactants is irradiated with ultra-violet radiation [2-4]. By the latter method it is possible to prepare dicyclohexyl sulphide with a yield of 80% of theory [12]:

~=.~,,~oo ~ [,,,,/) - 0

(5)

It must, however, be borne in mind that the initial cyclohexyl mercaptan is obtained by the interaction of cyelohexylmagnesium bromide with sulphur: yield ~ 60% of theory [5]. The yield of dieyclohexyl sulphide does not exceed 50% of theory when reckoned on the cyelohexyl bromide. Dieyclohexyl sulphide is formed together with other substances on heating cyelohexene with sulphur to 150 ° [6], and also by heating cyelohexene and hydrogen sulphide under pressure in the presence of a catalyst [7]. Attempts to carry out the preparation of dicyclohexyl sulphide according to the following scheme RSMe ~-P~Br K2S-~ 2RBr

;R~S (where Me is K or Ag)

* Neftekhimiya 1: No. 4. 473-481, 1961. 369

370

N. ['. VOLYNSKI[ el

al.

led to unsatisfactory results [5]. Hence, it is clear that dicyclohexyl sulphide and, consequently, the sulphoxide are substances of relatively poor availability. In the present work, we have attempted, by avoiding intermediate stages (cyclohexyl mercaptan, dicyclohexyl sulphide) to obtain dicyclohexyl sulphoxide directly, starting from the readily available cyclohexyl bromide and thionyl chloride according to the reaction 2RMgBr ~ S()CI2 -> R2SO-~MgCI2~ MgBr2.

(:~)

Together with the expected sulphoxide, dicyclohexyl sulphide was obtained in a yield, under the optimum conditions, of 600/o of theory. This reaction could be of interest for the production of sulphides from compounds containing halogens which are not capable of undergoing a double decomposition reaction with such alkaline reagents as the sulphides or the extremely unpleasant hydrosulphides of the alkali metals. In the literature there is a certain amount of rather contradictory it,formation relative to the interaction of mixed organomagnesium compounds with thionyl chloride. This reaction was first described, without yields being given, by Strecker [8], according to whom the action of SOCI~ (1 mole) on phenylmagnesium bromide (2 moles) with ice cooling led to the formation only of diphenyl sulphoxide; benzylmagnesium chloride yielded dibenzyl sulphoxide and a little dibenzyl sulphide. According to Grignard and Zorn [9], the action of SOCI z (1 mole) on isoCsHI1MgBr (3 moles) led to the formation of di-isoamyl sulphoxide and diisoamyl sulphide (yields 50 and 14%, respectively). In the case of C~HsMgBr, diphenyl sulphoxide was obtained with a yield of 59% of theory, and in the case of C2HsMgBr, only diethyl sulphide was obtained. The reactions take place according to the equations SOCI2 -- 2RMgX -: 2MgXCI-~R~SO,

(4)

S()CI2~- 3RMgX: 2MgXC1~ R3SOMgX --> I~2S+ ROMgX .

(,5)

These authors consider that reaction (5) proceeds in marked fashion with aliphatic organomagnesium compounds which, in the final account, reduce sulphoxides to sulphides. Oddo [10] refuted Strecker's results and showed that the main products of the reaction between SOC12 and RMgX are sulphides and not sulphoxides. By analogy with the reactions between SOeC1e and RMgX, Oddo proposed the following scheme: s()Cl 2= t~MgX__l~Cl ~ OS(MgX)CI,

(6)

OS(MgX)CI~ 2RMgX =~(MgX)~O+MgXC[ i- R.aS.

(7)

371

S y n t h e s i s o f sulphide, s a n d s u l p h o x i d e s

However, in work with CeH5MgBr, diphenyl sulphoxide was a by-product and no formation of CsHsC] was shown. These facts are not explained b y Oddo's scheme. Courtot and Paivar [11] were tim first to use reaction (3) to obtain sulphoxides of the naphthalene series: they prepared di-a-naphthyl and di-~-naphthyl sulphoxides, the yield of di-u-naphthyl sulphoxide amounting to 60% . In the present work the action of thionyl chloride on isoamy]-, phenyl-, cyclohexyl-, and ~-naphthylmagnesium bromides, and on phenyhnagnesium chloride, has been studied. YIELDS

OF

I)I-I~;OAMYL

IN

I)EPFNDENCE

AND ON

DIPHENYI, THE

SI'I,I)HII)I,iS

E;XPERIMENTAI~

AND

SI'LI)HOXII)I,;S

CONI)ITIONS

-(iso-C5 H n).,s; ) OCI~ f ( ' ~ H o- M g B r (

N()(~] 2 ' i s o - ( ! ; H l l M g B r `

Experiment

I

] 1 I "2

3

,,

(C6H5)2

( SO-(~5H 11)2~SO

(

4* : 5

(i

7

8

1 : 2 ! 1:3

1:2

I:l

1:3

---5, 3 61

~ 10, + 1 5 24

53

6

30

0

9

i

S()CI 2 : lCMgBr r a t i o (molar) ! l ' e m p e r a t m ' e , ~(' Yield of sulphide, ° o o f t h e o r y caleulale(1 on the lgMgBr taken Yield o f s u l p h o x i d e , 0o o f t h e o r y c a l c u l a t e d o n ( h e R M g B r t,aken

1:3

1:2 I 1:1

-5, ~ 5, 7'-8 42 58

12

0

fi, 7 65

~-5

0

0

42

6, 6, 10 -- 10 18 23

"~ l

35

* In this e x l ) e r m l e n t t h e s o l u t i o n o f i s o a m y ] m a g n e s i u m the solution of thionyl chloride.

1:'2 15, ~ 20

b r o m i ( l e was a d d e d to

lsoamyl- and phenyhnagnesiunl bronfides were studied in the most detail (see Table) which made it possible to compare the results obtained with data in the literature and to throw light on the question of the chemistry of the appropriate reactions in a new day. It follows from the Table that increasing the ratio between the thionyl chloride and the organomagnesium compound (in moles) from 1 : 3 to l : l leads to an increase in the yields of sulphides and a decrease in the yields of sulphoxides. In an experiment with a reversed order of addition of the reactants (an ethereal solution of iso-CsHnMgBr was added to an ethereal solution of thionyl chloride), i.e. with insufficient Grignard reagent in the reaction mixture, di-isoamyl sulphide ~md no sulphoxide was obtained. The facts given above cannot be explained fl'om the point of view of Grignard and Zorn's hypothesis [9].

372

N.D. VOLYNSKIIe t

al.

'

The data of these authors on the yields of di-isoamyl sulphoxide, amounting to 500/o, and of di-isoamyl sulphide, 14°/o of theory, in the reaction of 1 mole of SOCI 2 with 3 moles of iso-CsHllMgBr were not confirmed by our experiments (see Table, experiment 1). The mechanism of the reaction between SOCI 2 and organomagnesium compounds proposed by Oddo [10] was not shown in any way. It completely fails to explain the formation of sulphoxides (in particular, diphenyl sulphoxide) with quite high yields, which takes place on carrying out the experiment in the absence of an excess of thionyl chloride or at a low temperature (see Table; experiments 1, 5, 6, 8) with vigorous stirring of the reaction mixture. The results of Strecker [8], Grignard [9], and Courtot [11], and also the results of the present work, allow it to be taken as fully demonstrated that sulphoxides are formed in the reaction between SOC12 and RMgX. The production of mixed sulphides (see below) indicates that the formation of sulphoxides takes place in two stages, through chlorides of sulphinic acids in accordance with equations (s) and (9). It follows from the work of v. Braun and Weissbach [12] that the chloride of isoamylsulphinic acid, iso-CsHllSOC1, is not reduced b y thionyl chloride to iso-C~HllSC1 in 12 hours at room temperature. The chloride of phenylsulphinic acid, C6HsSOC1, is not reduced by thionyl chloride to C~HaSCI even on heating on the water bath for 15 minutes [13]. As will be seen below, these observations are very important in confirming the mechanism of the formation of sulphides which we propose. Our experiments have shown that, notwithstanding Grignard and Zorn's assertion [9], organomagnesium compounds do not react with sulphoxides, not only under the conditions of the synthesis of sulphides, but even at room temperature, at least in 2 hours.* On the other hand, it has been shown that sulphoxides, in contrast to chlorides of sulphinic acids, are very readily reduced by thionyl chlorides to sulphides, the rate of reduction of dicyclohexyl sulphoxide by far exceeding the rate of reduction of diphenyl sulphoxide. Depending on the conditions of reduction of the sulphoxides b y thionyl chloride, a greater or smaller amount of chlorinated products is formed together with the sulphides; these have not been studied further in the present investigation.* The action of thionyl chloride on sulphoxides cannot be considered as completely elucidated, and this work will be continued. Under the. conditions of the synthesis of su]phides from SOCI~ and RMgX, the formation of chlorinated products in appreciable amounts is not observed. * On boiling a benzene solution of diphenyl sulphoxide with phenyhnagnesium bromide for 23 hours, triphenylsulphonium bromide was formed with a yield of 49-4°~) of theory [14]. ¢ The formation of chlorosulphides by the action of thionyl chloride on diphenyi sulphoxide on heating was observed by Loth and Michaelis [15]; see also [16].

Synthesis of sulphidos and sulphoxides

373

It follows from what has been said above that the synthesis of sulphoxides goes in three stages, the third stage consisting hi the reduction of the sulphoxide first formed by thionyl chloride to sulphoxide:* R M g X v S()CI~ --> tCSOCI-~ MgXCI : RSOCI + R M g X --> R o s e + MgXCI : l{sSO + SOCI~ --> RsS + S()~CI 2 .

(s) (,q) (to)

By treating a mixture of two organomagnesium compounds having different radicals with thionyl chloride, we obtained a number of mixed sulphides-decyl cyclohexyl, phenyl ~-naphthyl, and cyelohexyl a-naphthyl sulphides. In addition, didecyl sulphide was obtained from decyl chloride and di-ctilaphthyl sulphoxide from a-bromonaphthalene. * We did not succeed in reducing di-a-naphthyl sulphoxide to the sulphide by means of thionyl chloride either at room temperature or at an elevated temperature. Apparently, this behaviour of a-di-naphthyl sulphoxide is connected with the electronegative character of the a-naphthyl radical. The question of the effect of the nature of the radicals on reduction by thionyl chloride will be considered in more detail in a separate communication. The product of the interaction of di-a-naphthyl sulphoxide with thionyl chloride is an extremely viscous mass from which no individual substance could be isolated. The di-isoamyl, didecyl, and dicyclohexyl sulphides were oxidised under standard conditions with hydrogen peroxide [17] to the corresponding sulphoxides. EXPERIMENTAL PART

Production of dicyclohexyl sulphide from dicyclohexyl sulphoxide 12 g (0.5 g-atom) of magnesium turnings and 70 ml of absolute ether were placed in a 0.5 1. flask fitted with a dropping funnel, reflux condenser. thermometer and mixer. A solution of 81.5 g (0.5 mole) of cyc]ohexyl bromide was then added at such a rate that the ether boiled continuously. After the addition of the whole amount of cyclohexylbromide, the reaction mixture was heated for a further 40 minutes and was then cooled with a mixture of ice and salt, and a solution of 59.5 g (0.5 mole) of thionyl chloride in 70 ml of absolute ether was added cautiously with vigorous stirring. The addition * Com'tot a n d P a i v a r [11] refer to the reduction of di-B-naphthyl sulphoxido to t,he sulphide by thionyl chloride. ¢ The d i - a - n a p h t h y l sulphoxido had a m e l t i n g p o i n t of 163-164 ° (after recrystallization f r o m benzene); yield a b o u t 57~o of theory. F o r further details see the w o r k of C o u r t e r and Pai'var [11], who obtained di-a-naphthy] sulphoxide with a m e l t i n g point o f 165% 25 Petroleum 3

374

N.D. VOI,YNSKn et al.

of thionyl chloride was carried out at such a rate that the temperature of the liquid did not exceed --5 to --3 °. After the completion of the addition of the SOC12, without removing the external cooling, the contents of the flask were decomposed with 100 ml of dilute hydrochloric acid ( l : 1). The ethereal layer was separated and washed first with water and then with 10% alkali solution. The aqueous layer was neutralized with a solution of alkali and extracted with ether; the ethereal extract was added to the main ethereal solution. The ether was distilled off, and the residue was boiled for 10 minutes with 20% alkali in a flask with a reflux condenser* and cooled, and a little ether was added, carefully separated from the aqueous alkaline solution and dried with anhydrous Na2SO 4. On distilling the product in vacuum, the cyclohexyl bromide which had not entered into reaction distilled over first--12.9 g (fraction boiling up to 80°/5 m m ) - - t h e n an intermediate f r a c t i o n (h.p. 80-120°/5 mm, 3.1 g), and then the dicyclohexyl sulphide distilled over at 120-125°/5 mm (26.3 g). The yield of product was 53~o of theory (or 63% of theory, taking the recovered cyclohexyl bromide into account). Repeated distillation yielded pure dieyclohexyl sulphide in the form of a colourless liquid boiling at 120°/4 ram, n 2° D 1-5150. Found, oJ. ,O' S 15.81. C12H~2S. Calculated, o/.. S 16-17. Literature data: ~ 1.5143 [2]; 1.5146 [5]. By oxidising the dicyclohexyl sulphide with the stoichiometric amount of hydrogen peroxide in acetic acid at 25 ° [17], dicyclohexyl sulphoxides was obtained in the form of snow-white crystals, m.p. 85.5-86 °. The yield of product (after recrystallization from n-heptane) was more than 88% of theory. Found, (!o: C 67.31; H 10.37; O 7.73;.S 14.61. C1~H22OS. Calculated, ~}>: C 67.23; H 10.35; O 7.46; S 14.96.I Literature data: re.l). 85.5-87 ° [18].

Preparation of didecyl sulphide and didecyl sulphoxide 59.5 g (0.5 mole) of thionyl chloride in 70 ml of absolute ether were added with vigorous stirring to the Grignard reagent prepared from 12 g of Mg (0.Sg-atom) and 88.2 g (0.5 mole) of n-decyl chloride. The conditions of carrying out the reaction and the working up of the product were similar to those described for dicyelohexyl sulphide. Distillation of the product was carried out in vacuum (1-5ram) from a Claisen flask with a wide side-arm fused on low down, which did not show * In some eases this ol)eration was bett,er carried out after first distilling tile product.

Syzlthesis or' sL,lphides and slll[)ho×ides

375

any effect (m the characteristics of the decoral)osition (it must be borne ill mind that didecy] sulphide itself distills in a good vacuum without decomposition). A fraction was collected with b.p. 180-210°/5 ram. Repeated distillation yielded 47.6 g of didecyl sulphide in the form of a yellowish oil which rapidly crystallized; b.p. 195 ° at 2 ram. The yield was about 60~o of theory. After recrystallization of the distilled didecyl sulphide from ethanol, ,.,6 white plates were obtained, m.p. 22-23 °, n v 1.4632. F o u n d , (~o: S 9.99. C 2 ~ H ~ . Calculated, ~o: S 10-19.

Literature data: n~ 1.4612 [19], m.p. 25-26 ° [20] 27-27.5 ° 121], b.p. 216-217°/5 mm [20]. Oxidation of the didecyl sulphide with the calculated amount of 1-[20.~ in acetic acid at 25 ° [17] yielded didecyl sulphoxide in the form of snowwhite plates (after recrystallization fl'om ethanol), melting at 52-53 °. The yield of recrystallized product exceeded 50~'o of theory. F o u n d , °/o: O 4.92; S 9.56. C20[-It2OS. Calculated, °/o: O 4.84: S 9.70.

Literature data: m.p. 79-80 ° [22].

Preparation of decyl cyclohexyl ,~ulphidt~ Solutions of 0.545 mole of C10H21MgCI and 0.545 mole of CGH11MgBr iu absolute ether were placed in a l-litre flask provided with a dropping fmmel, reflux condenser, thermometer, and stirrer. The mixture was cooled to S to --5 ° a~d a solution of 1.09 moles of SOC],, in 120 ml of absolute ether was added with vigorous stirring. The reaction conditions and the working up of the products were similar to those giveyl for dicyclohexyl sulphide. After triple vacumn distillation, 32g (0.125mole) of deeyl cyclohexyl sulphide were obtained, b.p. 150 153°/1 ram, j~o 1.4525. F o u n d , (!0: S 12"38. C~6Ha~S. Calculated,. (~,.,o. S 12.50.

Literature data: n~° 1-4820 [23]; b.p. 164-165/°2 mm [23J. In addition to the desired mixed sulphide, dicyclohexyl sulphide (14 go.071 mole) the purification of which without conversion into the sulphoxidc was difficult, and didecyl sulphide (35g-0"111 mole), readily purified by recrystallization from ethanol, were obtained as by-products.

Preparation of phenyl a-naphthyl sulphide A solution of 1 mole (119 g) of SOCI 2 in 100 ml of absolute ether was added to a mixture of 0.5 g-mole of phenylmagnesium bromide and 0.5 g-mole of a-naphthy]magnesium bromide in absolute ether. The temperature of 25*

376

N . P . VOLVNSKII et al.

the mixture was kept in the range 5-10 °. After the addition of the whole of the thionyl chloride, stirring was continued for a further 30 rain, and the mixture was then decomposed with 100 ml of dilute hydrochloric acid (1 : 1). The ethereal layer was separated off; the aqueous layer was extracted with ether and the ethereal extract was combined with the main ethereal solution. The crystals of di-a-naphthyl sulphoxide, which are insoluble ill water and sparingly soluble in ether, were filtered off and treated separately. The ethereal layer was washed with water and aqueous alkali, and dried with anhydrous Na2SO ~. The ether was distilled off and the residual (lark oil (115 g) was shaken with 200 nfl of n-heptane and allowed to stand, and ?,he upper heptane layer was decanted as completely as possihle. The part of the oil which did not dissolve in the heptane was shaken a fllrther 2 or 3 times with fresh portions of heptane. The heptane solutions were combined and allowed to stand for some hours. A small amount of dinaphthyl sulphoxide crystallized out. The heptane was distilled off (finally in vacuum) and the residue oil (80 g) was subjected to vacuum distillation. 25 g (0.106 mole) of phenyl a-naphthyl sulphide was obtained in the form of an oil boiling at 162°/1 ram, n~ 1.685. On standing in the refrigerator, the substance crystallized; it was carefully pressed out on a glass filter, and phenyl a-naphthyl sulphide was obtained in the form of white crystals with m.p. 40--41 °. Found, %: S 13.54. CleH12S. Calculated, %: S 13-57. Literature data: m.p. 41"8 ° [24]. In addition to the desired mixed sulphide, about 18.7 g (0.100 mole) of a diphenyl sulphide fraction (b.p. 110-113 ° at 1'5 ram) was obtained, the isolation of pure diphenyl sulphide from which without converting it into the sulphoxide was difficult. From the reaction products insoluble in heptane, 4.5 g of di-a-naphthyl sulphoxide was obtained after the addition of ether and cooling. (The total amount of di-a-naphthyl sulphoxide isolated was 6.9 g, 0.023 mole.) After distilling off the ether, a further 23 g of extremely viscous oil which could not be distilled in vacuum remained. This was not investigated in more detail.

Preparation of cyclohexyl u-uaphthyl sulphide A solution of 1 mole (l19g) of thionyl chloride in 100ml of absolute ether was added slowly with cooling and stirring to a mixture of 0.5 mole of CeHs1MgBr and 0.5 mole of a-C10HTMgBr in absolute ether. The conditions of the reaction and the working up the products were similar to those described for phenyl a-naphthyl sulphide. 8 g of di-a-naphthyl sulphoxide (after recrystallization from benzene the substance melted at 160°), 15 g of a dicyclohexyl sulphide fraction boiling

Synthesis of sulphides and sulphoxides

377

between 105 and 110°/2 mm (the isolation of the dicyclohexyl sulphide without converting it into the sulphoxide was difficult), and 39.1 g (0.162 mole) of a cyclohexyl u-naphthyl sulphide fraction boiling between 170 and 180°/3 ram* were obtained. Distillation of the latter fraction yielded cyclohexyl a-naphthy] sulphide in the form of a yellowish oil, b.p. 166-167°/1 ram, n ~ 1.6292. Found, °o: S 13.38. C16Hls~. (~alculate
Action of mixed organomagnesium compounds on sulphoxides (a) Action of phenylmagnesium bromide on diphenyl sulphoxide. 2.0g (0.01 mole) of diphenyl sulphoxide (m.p. 70.5-71.5 °) were dissolved in 70 ml of absolute ether, and the solution was cooled to --10 ° and mixed with a solution of 0.05 mole of phenylmagnesium bromide in 30 ml of absolute ether. The mixture was held for 1 hour at --10°; it was then decomposed with ice, and the minimum amount of hydrochloric acid necessary to bring the basic magnesium salts into solution was added, and the ethereal layer was separated, washed with water and alkali, and dried with anhydrous Na~SO 4. The ether was distilled off and the residue was triturated with hexane and filtered off; I. 1 g (55~o of the amount taken) of unchanged diphenyl sulphoxide were obtained; m.p. 70.5-72.5 °. No diphenyl sulphide or phenol were found. (b) Action of cyclohexylmagnesium bromide o~, dicyclohexyl sulphoxide. A solution of 0.07 mole of cyclohexylmagnesium bromide in 30 ml of absolute ether was added to a solution of 7 g (0-033 mole) of dicyclohexyl sulphoxide (m.p. 85-86 °) in 20 ml of absolute ether. The mixture was held for 1 hour at room temperature and was then decomposed with water and worked up as described for diphenyl sulphoxide (see "a"). 6.0 g (86% on the amount taken) of unchanged dicyclohexyl sulphoxide was obtained; washed with petroleum ether, the substance melted at ~1-5-83.5 °. No dicyclohexyl sulphide was found. (c) Action of isoamylmagnesium bromide on di-isoamyl sulphoxide. 6.8 g (0.036 mole) of di-isoamyl sulphoxide (m.p. 34-36 °) was added to a solution of 0.072 mole of isoamylmagnesium bromide in 30 ml of absolute ether. The mixture was kept for 2 hours at room temperature and was then decomposed with water and worked up as described for diphenyl sulphoxide (see "a"). * Distillation of this fi'action which showed no effect of decomposition on its cha. raeteristics was carried out, since cyclohexyl a-naphthyl sulphide itself distills in vacuum without decomposition.

378

N.P. VoI,YNSKI[ et al.

On distilling the reaction products in vacuum, 6.5 g (95% <)n the amount taken) of unchanged di-isoamyl sulphoxide was recovered (b.p. l l l°/3 mm m.p. 32.5-34.5). No di-isoamy] sulphide was found.

Action of thionyl chloride on sulphoxides (~t) Action of thionyl chloride on dicyclohexyl sulphoxide. 7.1 g (0.033 mole) of dieyclohexyl sulphoxide was dissolved in 30 ml of absolute ether and the solution was cooled to 15 ° and mixed with a solution of 4.3 g (0.036 mole) of thionyl chloride in l0 ml of absolute ether cooled to --15 °. The reaction mixture was held for 5 minutes at --10 to --5 ° and was then decomposed with ice and neutralized with a solution of alkali: the ethereal layer was separated and dried with anhydrous Na~SO 4. The ether was distilled off, and residue distilled in vacuum. 2.5 g of dicyelohexyl sulphide in the form of a colourless liquid with b.p. 110:114°/3 ram, n ',0 D 1.5140, werc obtained: in addition, 2.5 g of a colourless oil boiling between 130 and 140°/3 mm was obtained. This substance contained halogen and, probably, is the product of the simultaneous reduction and chlorination of dicyclohexyl sulphoxide, lit was not further investigated in the present work. (b) Action of thionyl chloride on diphenyl sulphoxide. 10.1 g (0.05 mole) of diphenyl sulphoxide (m.p. 70.5-71.5 °) were dissolved in a mixture of 75 ml of absolute ether and 35 ml of benzene, and the solution was cooled to o ° and 4 ml (0.056 mole) of thionyl chloride was added. The solution was heht at 1::~° for 40 rain and then at 16-19 ° for a further 1 hour. Working u]> similar to that described for dicyclohexyl sulphoxide (see " a " ) yielded 1.5 g of diphenyl sulphide (b.p. 120-125°/3'5 ram, n~ ~ 1.632), and 7-4 g of unchanged dipheny] sulphoxide (b.p. 170°/3.5mm; after washing with heptane, the material had m.p. 67.5-70.5: m.p. of a mixed sample with pure dil)henyl sulphoxide 68.5-71.5°). SUMMARY

l. The action of thionyl chloride on organomagnesium compounds has heen studied, the reaction conditions have been refined, and the applicability of this reaction to the production of a number of difficulty available sulphides, in particular dicyelohexyl sulphide, by omitting the stage of the formation of mercaptans, has been shown. 2. It has been shown t h a t the sulphoxides first produced are reduced to sulphides by the thionyl chloride and not by the organomagnesinm compounds. 3. The preparation of didecyl, dicyclohexyl, deeyl cyelohexyl, phenyl a-naphthyl, and eyelohexyl ~-naphthyl sulphides by the action of thionyl chloride on organomagnesium compounds has been carried out for the first time. Tra~.slated by B. J. H~AZZAR.t)

S y n t h e s i s of sulphidos a n d s u l p h o x i d e s

379

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