BRIEF COMMUNICATIONS

M E C H A N I S M F O R M E C H A N I C A L D E S T R U C T I O N

OF A M M O N I U M B R O M I D E S I N G L E C R Y S T A L S

F . K h . U r a k a e v , Y u , Pc S a v i n t s e v , O. F . P o z d n y a k o v , V . V . B o l d y r e v , a n d V . R . B e g e l '

UDC 541.124:542.92:546.39'141-162

A study of the m e c h a n i s m of mechanochemiea[ p r o c e s s e s is receiving constantly increas ing attention, par t ly due to the i r p rac t i ca l impor tance [1]. E i ther nonequil ibr ium vibra t ional ly excited pa r t i c les or unstable f ree rad ica l s a r e fo rmed in the f i r s t s tage of chemical des t ruct ion, init iated mechanica l ly i n i o n i c inorganic c ry s t a l s [2, 3].

In o rde r to obtain data for unequivocally choosing between these decomposi t ion m e c h a n i s m s we studied ~hose objec ts where the chemical consequences of the mechanica l action make it poss ib le to judge the e l e m e n t a r y mechano lys i s act . Th is condition i s sat isf ied by the NH4X compounds, where X = C I , Br , C104, etc. , which a re capable of decomposing in the following di rec t ions:

~ HBr + NH3 (1) NHaBr-- ' ~ Br + NH4 (NH3 + H) (2)

" ' Br + NH4 + ( in the lattice) ~2 e- (3)

React ion (1) is explained by the excitat ion of the v ibra t ional ly rotat ing levels of the ground state of the NH4 + cation, which i s completed by the t r a n s f e r of H + [4, 51. Reac t ions (2) and (3) a r e r ea l i zed only v ia e lec t ron ic p r o c e s s e s [6] and r equ i re much g r e a t e r ene rgy expendi tures than does (1).

E X P E R I M E N T A L

The t ime-o f - f l i gh t m a s s s p e c t r o m e t r y method [3] was used, which makes i t poss ib le to judge the degree to which reac t ions (1)-(3) p r o g r e s s f rom the ra t io of the in tensi t ies of the volat i le p roducts that a r e l ibera ted during the c leavage of NH4Br single c ry s t a l s , and consequently the mechan i sm for the mechanica l des t ruct ion of c r y s t a l s of the Ntt4X type, which is essen t ia l when studying t r anspo r t mechanochemica l reac t ions [7] where a m m o n i u m sa l t s a r e used as the t r a n s p o r t agents .

The N[I4Br single c ry s t a l s were grown f rom aqueous solutions a t 30-35~ by the method of lowering the t e m p e r a t u r e (cooling ra t e 0.05-0.1 deg/day) . The appara tus used to grow the c rys t a l s was hydrophobized in advance. The h e r m e t i c seal ing of the solution and r e v e r s e turning of the seed c rys t a l were done as descr ibed in [8]. Urea was added in o rde r to p reven t dendr i t ic growth in the solution. However , in this case the c rys t a l s had a brownish t inge, apparen t ly due to the format ion of smal l amounts of NH4Br 3 [9], s ince, based on the m a s s - s p e c t r o m e t r i c data, f ree Br 2 is absent in these c rys t a l s . Only the addition of aqueous NH 3 solu- tion to the c ry s t a l l i z e r made i t poss ib le to g row co lo r l e s s c ry s t a l s with a size of ~ 10 x 10 • 10 mm. The employed NHaBr single c rys ta l s were obtained f rom a solution with the composition: NH~Br-900 g / l i t e r , urea =300 g / l i t e r , and 10% NH 3 solut ion=440 m l / l i t e r .

The NH4Br single c rys t a l s a r e quite p las t ic at ~ 20 ~ and fail to undergo bri t t le dest ruct ion. The r emova l of occluded moi s tu re by heating the c rys t a l in the chamber of the m a s s ana lyze r proved imposs ib le due to the volatility- of the sample . Consequently, the method given in [3] was modified. Before and during the m e a s u r e - ments the c rys ta l was constantly cooled with the vapors of liquid N 2 (on the ave r age down to -70~ The expe r imen t s with the cooled c rys ta l s made i t poss ible , f i rs t , to achieve bri t t le des t ruct ion of the NH4Br single c rys ta l s , second, to f reeze out the mois tu re , which i n t e r f e r e s with the c o r r e c t running of the exper iment , and third, to exclude the sublimation of NH4Br. The vacuum p r io r to m e a s u r e m e n t was 5 �9 10 -7 to r r , while the sensi t iv i ty of the method toward the gas s t r e a m was ~ 10 ll m o l e c u l e s / s e c pe r m m of scale subdivision.

Inst i tute of Phys icochemica l P r inc ip le s of P r o c e s s i n g Mineral Ores , Siberian Branch of the Academy of Sciences of the USSR, Novosibirsk . A. F. Ioffe Physicotechnical Inst i tute, Academy of Sciences of the USSR, Leningrad. T rans la t ed f rom Izves t iya Akademii Nauk SSSR, Seriya Khimicheskaya , No. 4, pp. 924-926, Apri l , 1978. Original a r t i c l e submit ted March 2, 1977.

0568-5230/78/2704-0799507.50 �9 1978 Plenum Publishing Corporat ion 799

15-z7

r 18

#O-~i

28 323# #r 7,.0-82 ~/'E"

h8 # rn/e 80

i T i i

�9 # ~g f z,5 z 2,5 s

Fig. 1. Exper imenta l data on mechanical destruct ion of NH4Br c rys ta l s : a) m a s s spec t rum of volat i le products fo rmed in cleavage of single c rys ta l ; b) kinetic curve for in tensi ty of HBr l iberat ion (m/e 80), r eco rded on ribbon of beam osci l lograph during cleavage of single crys ta l .

A compar i son of the obtained m a s s spec t rum (Fig. la) with.the m a s s spec t r a of pure NH s and HBr [10] r evea l s that the volat i le products of the mechanical destruct ion of NH~Br a re NH s and HBr, which a r e l ibe r - ated in approx imate ly equal amounts (1014-10 is molecules /cm2) . I f water preva i led in the volat i le products obtained in the exper imen t s descr ibed in [3] on the destruct ion of the c rys ta l s at ~ 20 ~ then, as can be seen, the amount that is l ibera ted during the cleavage of the cooled c rys t a l s is slight. T r a c e s of a i r inclusions (m/e 28 and 32) and CI- , which cor responds to the l iberat ion of HC1, a r e also observed in some of the ex p e r i - ments in the NH4Br c rys ta l s .

The curve for the change in the intensi ty of HBr l iberat ion (m/e 80), r ecorded on the ribbon of a beam osci l lograph (the t ime constant of the scheme for record ing the kinetic curve is 0.01 sec), is not smooth (see Fig. lb) and apparent ly re f lec t s the complex sequence of the p roce s s for des t roying the sample and the subsequent re laxat ion of the mechanica l ly ac t ivated f resh ly formed sur faces .

The m a s s - s p e c t r o m e t r i c m e a s u r e m e n t s lack any indications that reac t ions of type (2) and (3) can be rea l ized during the cleavage of NH4Br single c rys ta l s . This gives reason to a s sume that the mechan i sm for the mechanical des t ruct ion of NH4Br c rys t a l s consis ts in the t r a n s f e r of H + f rom NH~ + to B r - , for example , due to excitat ion of the optical v ibra t ions of the lat t ice during the mechanical action [6]. Elec t ronic p r o c e s s e s , typical for the c h e m i s t r y of the cleavage of alkali halide c rys ta l s [6, 11], a r e not real ized, since a sufficiently efficient mechan i sm for absorpt ion of the mechanical energy ( t ransfer of H +) exis ts on a lower step of the energy scale .

CONCLUSIONS

It was shown by the time-of-flight mass spectrometry method that a proton is transferred from the cation to the anion during the mechanical destruction of ammonium bromide single crystals.

L I T E R A T U R E C I T E D

1. V . V . Boldyrev, A. S. Kolosov, M. V. Chaikina, and E. G. Avvakumov, Dokl. Akad. Nauk SSSR, 233, 892 (1977).

2. V.V. Boldyrev, Kinet. Katal., i__33, 1411 (1972). 3. F. Kh. Urakaev, V. V. Boldyrev, O. F. Pozdnyakov, and V. R. Rege1', Kinet., Katal., ~ 350 (1977). 4. E~ F. Khairetdinov and V. V. Boldyrev, J. Solid State Chem., 1_~i, 67 (1974). 5. E.F. Khairetdinov, V. V. Boldyrev, and A. I. Burstein, J. Solid State Chem., 10, 288 (1974). 6. L.M. Belyaev, Yu. N. Martyshev, and Yu. Ya. Yushin, Acta Phys. Acad. Set. Hung., 3_.33,307 (1973).

800

7. E . G . A w a k u m o v , V. V. Boldyrev, and I. D. Kosobudskii , Izv. Sibirsk. Otd. Akad. Naak SSSR, Set . Khim. Nauk, 1972, No. 9, I s sue 4, 45.

8. V. N~ Voitsekhovski i , Zap~ Vseso Mineralog. Obshch., 92, No. 5, 587 (1963). 9. W. Gabes and H. Gerding, J. MoI. Struct . , 14, 267 (1972).

10. A. Gornu and R. Massot , Compilat ion of Mass Spectral Data, Heyden and Son, London (1966). 11. T . E . Gallon, J. G. Higginbotham, M. Prutton, and H. Tokutaka, Surf: Sei., 2_~1, 224 (1970).

ALKYLATION OF 3-SUBSTITUTED CYCLOHEXANONE

ENAMINES

E. N. Aredova, P. A. Krasutskii, M. M. Krayushkin, S. S. Novikov, V. V. Sevost'yanova, and A. G. Yurchenko

UDC 66.095.253:547.594.3

The behavior of 4-subs t i tu ted cyclohexanone enamines when condensed with ac ry loy l chloride was descr ibed in a prev ious communicat ion [1]o The behavior of cyclohexanones that have a substi tuent in the 3 position was studied in the p resen t paper . In cont ras t to 4-benzoylcyelohexanone, 3-benzoylcyclohexanone (iiI) does not fo rm the enamine when reac ted with morphol ine. Ins tead the morpholine sal t of benzoic acid (IV) is fo rmed under a wide range of conditions.

o . o ( I ! II "N /

H (iv) OH 0COC6H5 OCOC~H~ C~HsC()OH

I lI III

In cont ras t to 1,4-cyclohexadione, 1 ,3-cyclohexadione (V) r eac t s with morphol ine to give only the monoenamine (VI).

H a " ~ t ' ~ Ha, l'I,,

o s~( 2 < . "~" "6.n ~ ~v) ti, ~,, L../6

{\l)

CH ~CIICOC[

0

" ~ ~ ( V l I ) 0

e

~162 ~ e OHalA)

d

In cont ras t to monoketone enamines , 1 -morphol inocyc lohexen-3-one (VI) is stable, which can be explained by the conjugation of the carbonyl group with the in t racyc l i c double bond. This apparent ly explains the fact that the a lkylat ion of enamine {VI) with ac ry loy l chloride leads to the monoalkylat ion product (VIII) and not the b icyel ic product (VII). Probably , due to conjugation with the carbonyl group, in (VI) the i somer iza t ion of the double bond in the 6 posit ion is made difficult and alkylat ion at this center fails to occur . Since in the l i t e r a - ture only the melt ing point i s given for (VIII), additional data was needed in o rde r to identify the compound obtained by us. The H A and H B protons have acid p roper t i e s , and acid (VIII) when t i t ra ted with 0.1 N alkali solution behaves like a dibasic acid (g-eq =92, which is half of the molecu la r weight). The NMR spec t ru m of (VIII) was taken in pyridine and is eas i ly in te rp re ted as being the spec t rum of the pyr id in ium salt: 12.97 = 2H a (region of acid protons that f o rm an H bond), 2.95 =2Hb, 2.86 =2He, 2.44=2He, 1.84=2Hd .

N. D. Zel inski i Inst i tute of Organic Chemis t ry , Academy of Sciences of the USSR, Moscow. Kiev Poly- technic Inst i tute. T rans la t ed f rom Izves t iya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 4, pp. 926-928, Apri l , 1978. Original a r t i c l e submit ted March 22, 1977.

0568-5230/78/2704- 0801 $07.50 �9 1978 Plenum Publishing Corpora t ion 801