explanations. It is hoped that further work now in progress in this Laboratory will contribute toward the solution of this and several other related general problems pertaining to hyperconjugation. Experimental Kinetic Procedure .-The kinetic method, the analyses for bromide ion and for olefin have been tiescribcd previo1isly.~3 All bath temperatures were set by Beckninnn thermometers stantlardized in the baths a t the exact temprrature desired against the same platinum resistance thermometer and Mueller bridge arrangement, sensitive to a few thousandths of a degree. The temperature accuracy, not limited by the calibration standard should be of the order of 1 0 . 0 1 or less. For the isopropyl bromide kinetic runs the bromide ion was extracted in an aqueous solution and titrated with silver nitrate solution directly using a potentiometer :irrangemerit with a silver electrode as the indicator. Tlic details of this procedure will be published later. Preparation of Organic Compounds.-A sample of 62.5 g. (0.55 mole) of 4,4-dimetliyl-2-pentan0ne,'~ b.p. 124-125" (760 mm.), n z 51.4015, ~ was added slowly to a slurry of 7.6 g. (0.2 mole) of lithium aluminum hydride in 600 ml. of d r y ether under dry nitrogen. The excess hydride was decomposed with water and the mixture was poured on 500 ml. of ice-cold 10% sulfuric acid. The ether layer and the ether extracts of the water layer were combined, washed, dried with anhydrous potassium carbonate and distilled. 4,4-Dimethyl-2-pentano1, 40 g. (0.34 mole), was collected a t 137138' (751 mm.); n% 1.4168; yield 62%. 4,4-Dimethyl-2-bromopentane, 24.9 g. (0.14 mole), b .p. 59.3-59.8' (33 mm.), 1.4439, was prepared by the slow addition of excess gaseous hydrogen bromide to 42.5 g. (0.37 mole) of 4,4-dimethyl-2-pentanol a t about 60". 4-Methyl-2-pentano1, 41.2 g. (0.41 mole), b.p. 132", was prepared following the usual Grignard technique from 137 g. (1.0 mole) of isobutyl bromide and 50 g. (1.1 moles) of acetaldehyde, b.p. 20.5-21 '. 4-Methyl-2-bromopentane, 45 g. (0.27 mole), b.p. 33" (mm.), was prepared from 41 g. (0.41 mole) of the corresponding alcohol and gaseous hydrogen bromide. O
(13) V. J. Shiner, Jr., THISJ O U R X A L , 74, 5285 (1952). (14) W. A. Mosher and J . C . Cox, i b i d . , 72, 3701 (1950)
4,4-Dimethylpentene-l, 105 g. (1.07 mole), b.p. 71.071.8" (755 mm.), n 2 5 ~1.3902, was prepared by the addition of 5.0 moles of t-butylmagnesium chloride t o an ice-cold solution of 605 g. (5.0 moles) of allyl bromide in ether. This material was redistilled in a 75-plate It'heeler concentric tube column and separated into 14 fractions. T h e infrared spectra of fractions 6 to 12, recorded parallel t o one another on the same chart, using a Perkin-Elmer Model 21 infrared recording spectrophotometer, showed no differences between fractions. A cooling curve taken on a portion of the mixture of these fractions with a two-junction copper-constalltan thermocouple calibrated at four points s h o w d f .p (initial) -137.62", f.p. (half-frozen) -137.70'. 4,4-Dimethylpentene-2, b.p. 76.7-76.8", n Z k 1.3900, was prepared by the dehydration of 4,4-dimethyl-2-pentanol and was purified by distillation through the 75-plat? concentric tube column. The infrared spectra of successiv? fractions again showed a good "flat" and a cooling curve 011 the fraction used gave f . p . (initial) -118.88°; f.p. (halffrozen) -119.04O.4-Methylpentene-1 was prepared by the addition of isourouvlmamesium bromide t o allyl bromide and was purified by distillGion through a 40 X 0.9 cm. column packed with phosphorbronze screen helices and equipped with a partiai take-off head. All other organic compounds used, except solvents, were carefully purified by distillation through a 50 X 1.0 cm. vacuum-jacketed column packed with 3/12'' glass helices and equipped with a partial take-off head. Preparation of Kinetic Mixture of Olefins.-A sample of 9.7 g. (0.54 mole) of 4,4-dimethyl-2-bromopentane was thoroughly mixed with 100 ml. of about 1 N sodium ethoxide in absolute ethanol and allowed to react a t 45' for about ten half-lives. The contents were then mixed in a separatory funnel with 800 ml. of water and fifty ml. of fractionally distilled petroleum ether (b.p. 28'). The organic layer was separated and the aqueous layer was washed with two more portions of petroleum ether. The combined petroleum ether extracts were dried over anhydrous potassium carbonate and most of the petroleum ether was removed through a 40 X 0.9 cm. total reflux, partial take-off column packed with phosphorbronze screen helices. The residue was then distilled through a 20 X 0.6 cm. straight-tube column and 3.0 g. (0.031 mole) of olefin was collected, b . p . 69-78'. The olefin composition of this sample was determined by comparison of infrared spectrum with that of synthetic mixtures of known concentration. BLOOMINGTON, INDIANA
[ C O N T R I B U T I O N FROM TIIE DEPARTMENT OF CIIEMIS TRY, PURDIJE LTXIVERSITY]
The Reaction of Silver Nitrite with Secondary and Tertiary Alkyl Halides',' BY
NATITAN
KORNRLIJM, ROBERT-4. SMILEY, I ~ E R B E RE.T UNGNADE, *ALAN hf. AND STEPHEN A. HERBERT, JR.
i\rHITR, B E R N A R D
TAUB
RECEIVED MAY23, 195.5 Treatment of secondary halides with silver llitrite gives nitroparafins in cn. 15% yields. The reaction of tertiary halides with silver nitrite is even less useft11 as a rnealls of prt.paring rlitroparafiins (0 to 5% yields). T l ~ ecoinplex mixtures produced have been shown to contain, in addition to t l i ( 3 :dntiril)xi(~d Ilitrop:lrafins 311d nitrite esters, olefins, nitrate estrrs and adducts of olefins with oxi(1rs o f nitrogen.
I n the preceding paper3 i t was shown that the reaction of primary bromides and iodides with silver nitrite gives excellent yields of primary nitroparaffins. The present study is concerned with the utility of this reaction for the synthesis of secondary (1) Paper V I in t h e series "The Chemistry of Aliphatic and Alicvclic Nitro Compounds." (2) This research was supported by t h e United States Air I'orcc tinder Contract No. AI? 18(000)-310 rnoniti,red by the OHirt. ; 131 + A g S O J +i l g S + H S O n
1.1200; (b) reduction of 4-heptanonc (b.p. 1-13 , n Z o D 1.4070) with lithium aluminum hydride (60-75% yield); b.n. l 5 5 " , 84" (45 mm.). E ~ @ D1.4202; lit. valuesI3; b . p . li5-155.4', nZ0D1.4205. 2-Methyl-5-octanol was synthesized by treating 12butyraldehyde with isoamylmagnesium bromide; yield i 1 % , b.p. 72" (8 mm.), n2% 1.4262; lit. values'4: b . p . (CHj)BC-OH f HNOl (CHA)~C-OXO f H.0 89" (18 mm.), T Z ~ O D 1.426. T o test this possibility, 0.5 mole of t-butyl chloride Reduction of phenylacetone with lithium alurninuin hywas treated with 0.65 inole of silver nitrite in the dride gave 1-phenyl-2-propanol in 91% yield, b.p. 110" (20 n20~ 1.5210; lit. values: b.p. 116" ( 2 5 m m . ) , 1zZ5D presence of 100 g. of Drierite. The yield of /-butyl mm.), 1.5195IKa; N ~ O D 1.5190.16b nitrite was 63(,ij identical with the yield in the ab2-Methyl-2-octanol was obtained in 67y0 yield by action of n-hexylmagnesium bromide on acetone; b . p . A5 TABLE I1 (2 mm.), TZ~OJI 1.4280. KirrmannI6 reports b.p. 81" (13 ~ T H E KEACTIOS O F S I L V E R S I T R I T E ~VI'TII' h R T I A R ' i HALIDES mm.), n I 9 1.4299. Halides.-2-Chloropro~ane (b.p. 35", n Z o1~.:3776), 2ll~lroiiaraik, Halide ,I Nitrite ester, %, chlorobu2ane (b.p. 67.7 , ~ 2 1.3967), 0 ~ t-butyl cltoride (b.p. 51 , n Z o1.3856) ~ and t-amyl chloride (b.p. 85 , n Z o i ~ t-Butyl chloride 4-6 63-6ib 1.4054) were commercial samples which had been purified t-Butyl bromide 0" 63-64b carefully. 2-Chlorooctane was prepared from 2-octanol &Butyl iodide 0 0" (purified via the acid phthalate) by treatment with thionyl t-Amyl chloride 5-6 57-5gh chloride and pyridine, and then rectifying (b.13. 6 3 " (14 mm.), n Z 01.4259). ~ 0 50-60b &Amyl broniidc 2-Bromopropane (b.p. 59 ', % % O D 1.4246) and 2-broinobuc 19d 2-Me-2-chlorooc time tane (b.p. 90", n 2 @ D 1.4367) were obtained by washing coin0 33" 2-h~e-2-bronioocta11c mercial samples with concentrated hydrochloric acid, water, 10% aqueous sodium bisulfite, 10% aqueous sodium car111 a n early experinlent (by B. T.) an 8% yield of tiiittobutane \viis obtaincd, but this could not be repeated by bonate and then with water. After drying over sodium the bromides were rectified. t-Butyl hroinide ( b . p . R , A . S. 0 1)eterniined sricctronliotonietricallv iultravio- sulfate Ict I . A small \.ieiti ( s i i . :i"/c) df wh,tt :cppeaqs to be im- pure _"-metli?.l-2-nitrobctane obtainerl, d B 58 0 (11) Microanalyses b y Galhraith Lahoratorles. I i n n x v l l l e . 'l'?ntl (12) A I . Smith and H. Adkins, THISJ O t : R i i . 4 1 , 6 0 , 657 (19371. ( 3 mill,), n20D 1,1188, ( 4 ~ r i ~ l l %~Z O) D, 1.4189. r B , p , (13) M. I,. Sherrill, ibid., 52, 1982 (1030). 111 >tdditiotl,a 287, 1-ield of 3-methyl-3-octLt1101(n'% 1.4280) (14) M. T u o t , Conzpt. r e % d . ,202, 1330 (1936). \V:IC isolated.
(CH,)1CX
--+
til:
,,,,
10) I1 Raldock, N. L e v y and C. W. Scaife, J . Chetn. S O C . . 2627 ' l ~ 8 4 ! 1 1 , A . \ I i c h n r l a n d G. €1. Ciirlbou. J . O r e . C/zem., 6 , 1 (1940). i
(15) (a) H. H. Zeiss a n d M . Tsutsui, T a m J O U R N A L , 76, 898 (1953); (I,) R. H. Pickard and J. Kenyon, J . Chem. Soc., 106, 1115 (1914). (16) A . Kirrmann. Coiupl. cud., 184, 1163 (1927).
REACTION OF SILVER NITRATEWITH sec-
Nov. 5, 1955
AND
L-ALKYLHALIDES
553 1
TABLE I11 CONSTANTS AND ANALYSES OF ALKYLHALIDES B.P.,
Halide
O C .
Mm.
WzoD
Carbon, 70 Calcd. Found
Hydrogen, 70 Calcd. Found
11.77 11.54 66.44 66.72 86 27 1.1290 2-Me-2-chlorooctane 9.24 9.36 52.16 52.35 59 3 1.4533 2-Me-2-bromooctane 9.24 9.23 52.16 52.41 45 2 1.4528 2-Me-5-bromooctane 5.54 5.89 54.24 54.56 89 3 1.5436 1-Ph-2-bromopropane" 7.28 7 60 39.80 39.58 49 105 1.4406 &Amyl bromide 6.65 6.85 37.16 37.34 93 30 1.4920 4-Iodoheptane 7.48 7.08 42.52 -12.68 72 4 1.4871 2-Me-5-iodooctaneb 4.47 1.75 43.59 43.90 93 2 1.5850 1-Ph-2-iodopropaneC a Prepared by treating the tosylate of 1-phenyl-2-propanol with anhydrous lithium bromide in dry acetone at room tcmperature for two days. Anal. Found: Br, 40.20, 40.01; calcd. Br, 40.14. Prepared by G. E. Graham of this Laboratory. Prepared by treating the tosylate of 1-phenyl-2-propanol with sodium iodide in anhydrous acetone for t n o days a t room temperature.
7 3 " , nz0D 1.4276) was prepared from the alcohol by treatment with a mixture of 48yo aqueous hydrobromic acid and 96% sulfuric acid a t a temp. below 5". 2-Bromooctane (b.p. 60-61" ( 5 mm.), ZZoD 1.4502) and 4-bromoheptane (b.p. 72" (34 mm.), n Z o1.4498) ~ were obtained from the corresponding alcohols and phosphorus tribromide. Sherrill's reports b.p. 64' (16 mm.), nZoD1.4495 for 4-bromoheptane. 2-Iodopropane (Columbia) was washed with aqueous sodium bisulfite, with water, dried over anhydrous magnesium sulfate and then rectified (b.p. 88.9", 13% 1.4987). All the other secondary iodides used in this study (except 1-phenyl-2-iodopropane) were prepared by treating the alcohols with red phosphorus and iodine: 2-iodobutane (b.p. 118.2", nZoD1.4995), 2-iodooctane (b.p. 83' (10 mm.), n% 1.4886). t-Butyl iodide was prepared according to Norris"; the product after washing with aqueous sodium bisulfite was dried quickly over anhydrous sodium sulfate and distilled (b .p . 99 O , +D 1.4899). The remaining halides employed in this investigation are either new compounds or have been inadequately characterized heretofore. Their properties are given in Table 111. Alkyl Nitrites.-The secondary and tertiary nitrite esters needed as reference compounds were prepared from the corresponding alcohols; Table IV summarizes their properties. The following procedure18 exemplifies the method of synthesis employed, unless otherwise stated in Table IV.
TABLE IV CONSTANTS AND ANALYSES OF ALKYLNITRITES B.p., OC. Nitrogen, yo
Nitrite
(mm.)
X2"D
Calca.
Found
I ~ o p r o p y l ' ~ ~ 39.9-40 1.3520 1 5 . 7 1 4 , 9 2-Butyl 68.2-68.5 1.3712O 4 - H e ~ t y l ~ , ~ 71 (62) 1.4038 9.67 9.66 63 (16) 1.4090° 2-Octyl" 2-Me-5-octyl 63 (10) 1.4140 8.09 7.97 1.4892 8 . 4 8 8.84' 1-Ph-2-propyl" 57 (1) 2-Ph-1-propyl' 58 (2) 1.4946 8.48 8.3Y 1.3890h t-Amyl 69 (338) 2-Me-2-octyl 56 (3) 1.4186 8 . 0 9 8.18 a Obtained by treating the alcohol with nitrosyl chloride according to N. Kornblum and E. P. Oliveto (THISJOURNAL,69, 465 (1947)). * Obtained by treating the alcohol with sodium nitrite and sulfuric acid (W. A. Noyes, ibid., 5 5 , 3888 (1933)). N. Kornblum, J . T. Patton and 3. B. Sordmann (THIS JOURNAL,70, 749 (1948)) report b.p. 6S", n% 1.3710. d T h e procedure of ref. 18 gave 1-heptyl nitrite of nZoD 1.4041. e N. Kornblum and E. P. Oliveto (ref. a ) report n20D 1.4082. ' A n a l . Calcd. for CgH11N02:C, 65.45; H, 6.66. Found: C, 65.52; H , 6.51. Q A n a l . Calcd. for CgH11N02: C , 65.45; H, 6.66. Found: C, 65.20, 65.66; H , 6.98, 6.94. h L i t . value: b.p. 63" (345 mm.), nl'D 1.3904 ( S . D. Wilson and E. F. Yang, Chinese J . Plzysiol., 4, 391 (1930)). Preparation of 2-Methyl-2-octyl Nitrite.-In a threenecked flask fitted with a stirrer and dropping funnel were (17) J. F. Norris, A m . Chem. J . , 88, 640 (1907). (18) A. Chretien a n d Y . Longi, C o m p f . ~ c n d .210, , 746 (1945).
placed 43.2 g. (0.3 mole) of 2-niethyl-2-octanol and 41.4 g. (0.6 mole) of sodium nitrite dissolved in a minimum amount of water. The mixture was cooled to 0' and then, with continuous stirring, 71 g. (0.12 mole) of aluminum sulfate ( 18H20)dissolved in sufficient water to give a 40% solution was added over a period of one hour. After addition was complete, the reaction mixture was stirred a t ice temperatures for two more hours and poured into a separatory funnel; the aqueous layer was removed, and the yellow organic layer was washed three times with water and dried over anhydrous sodium sulfate. RectificationI2 gave 37.8 g. (72% yield) of 2-methyl-2-octyl nitrite having a constant b.p. and n% (cf. Table IV). The Reaction of 4-Bromoheptane with Silver Nitrite.With minor variations the following is typical of the experiments on which the data of Table I are based: In a 3-necked flask fitted with a stirrer, dropping funnel and reflux condenser protected with a drying tube were placed 116 g. (0.75 mole) of silver nitrite and 200 ml. of anhydrous ether. The mixture was cooled to 0" by an ice-bath and with continuous stirring (in the absence of light) 89.5 g. (0.5 mole) of 4-heptyl bromide dissolved in 50 ml. of ether was added over a period of two hours. After the addition was complete the mixture was stirred a t 0' for 24 hours and then allowed to come to room temperature and stirred for 22 hours more. At this time the supernatant ether solution gave a negative Beilstein test and no precipitate was obtained when a saturated solution of silver nitrate in acetonitrile was added to two drops of the ether solution which had been diluted with a n equal volume of methanol. The silver salts were removed by filtration and thoroughly washed with ether. The filtrate and extracts were combined and the ether was removed by pumping a t 55 mm. for three hours, a train of three traps cooled t o -80" (Dry Ice) being employed as receivers. Only the first trap had any contents (I). The material ivhich had not volatilized then was distilled under reduced pressure (first at 53 mm. and then, gradually down to 15 mm.). The distillate was divided into four portions: (a) the most volatile fraction which condensed in the Dry Ice trap interposed between the system and the pump. This was combined iql-ith I and from the resulting ethereal solution I1 3-heptcne was isolated as described below: ( b ) 20.9 g . of material boiling from 40" (53 mm.) to 70" (15 mm.); all these fractions were yellow and had nZoD1.4043-1.4145: (c) 14.1 g. of material b.p. 70-80' (15 mm.), n% 1.4189-1.4234; the first fractions were yellow, the last colorless: ( d ) 5.76 g. of b.p. 8082' (15 mm.), nZoD 1.4241-1.4310; the first part of this material was colorless, the last yellow. The residue from this distillation weighed 2.3 g. and was a deep yellow liquid. 3-Heptene .-When the ethereal solution I1 was dried over anhyd. magnesium sulfate and rectified, 6.2 g. (13% yield) of 3-heptene was isolated, b.p. 95-96", n% 1.4049; lit. valueIg: b.p. 94", n Z o D 1.4049. Anal. Calcd. for C7Hlr: C, 85.63; H, 14.37. Found: C, 55.53, 85.86; H, 14.15, 14.29. The olefin decolorized bromine in carbon tetrachloride solution and reacted instantaneously with potassium permanganate. ' 4-Heptyl Nitrite.-Upon rectification the 20.9 g. of (b) gave 15.2 g. (22% yield) of 4-heptyl nitrite, b.p. 67' a t 50 mm., nzoD1.4041 (cf. Table 1 1 7 ) . (10) V. Ipatieff and A. Grosse, THISJ O U R N A L . 57, 1616 ( 1 0 3 3 ) .
5532
Vol. 77 TABLE
v
CONSTANTS A N D ANALYSES OF
SITROPAKAPFINS
Analyses,
r
Corn p o 11 t i d
n.p., @ C (. I r l m . )
Calcd. H
c
u%
2-Nitrobutane 4-Kitrolieptane
78 (100) 86 (20)
1,4043 1.4240
2 - S i troiietiuie 2-~~e-5-iiitroiictaiie
66 ( 2 j 75 (8j
1.4280
1.4320
02.YS
(Jn(2J 125-127 78 (65)
1.3131) 1,4022 1.4142
63
1-Pli-2-nitropropaiie 2-Ble-2-iiitropropaiie 2-Me-2-nitrobutane
46.23
57.03
4-Heptyl Nitrate.-The 14.1 g. of ( c ) W E sliakcii with four 10-id. portions of 10% sulfuric acid for a few iuiiiutcs and then overnight with 32 ml. of 10% aq. sodium hydroxide. Ten nil. remained undissolved and furthcr shaking wit11 aqueous alkali caused no furthcr volume change. T h c combined aqueous alkaline solutions were washed with petroleum ether (b.p. 35-37'), the petroleum ether phase was added to the alkali-insoluble layer, washed with water and dried over anhyd. magnesium sulfate. The petroleum ether solution (100 ml.) then was passed through a column of 50 g. of activated alumina and the column then was eluted with 500 ml. of petroleum ether. Distillation gave 6.3 g. (8% yield) of colorless 4-heptyl nitrate, b.p. 85' (25 m m . ) , n Z o 1.4207. ~ Anal. Calcd. for Ci.Hl6s03: C, 52.15; H , 9.38; N, 8.69. Found: C, 52.32, 52.41; H, 9.40, 9.53; X, 8.87, 8.72. Infrared analysis showed the complete absence of -OH (2.68-2.84) and the characteristic covalent nitrate bands were present a t 6.15, 7.85 and 11.5 p . 4-Nitroheptane.-The aqueous alkaline solution obtained in the isolation of 4-heptyl nitrate was acidified rvith an icecold saturated water solution of hydroxylamine hydrochloride arid allowed t o stand at 0' overnight. After extracting with petroleum ether and drying over magnesium sulfate thc 4-nitroheptane was isolated by distillation; yield 5.4 g . (7%), b.p. 07" (7 mm.), %'OD 1.4247. Anal. Calcd. for C7HijKO2: C, 57.93; H, 10.4; X, 0.65. Foulid: C. 57.95, 58.15; H, 10.44, 10.32; X, 9.46, 0.68. Infrared analysis showed the typical nitro bands at 6.45 and 7.37 I.(. The 5.76 g. of material labeled ( d ) , b.p. 80-82' (15 mm.), probably contained considerable 4-nittoheptane since 75% of it dissolves in aqueous alkali. I n some runs appreciable amounts of alcohols are obtained. These presumably arise from the hydrolysis of nitrite esters. Olefin-Oxide of Nitrogen Adducts. (a) From the Reaction of I-Phenyl-2-iodopropae with Silver Nitrite.-After conducting the reaction in the usual way the silver salts were removed by filtration and the ether solution of products !vas placed in a refrigerator. After two days a small amount of white crystals had appeared. These were recrystallized from acetone; m.p. 130-133" dec. These crystals arc insoluble in ethanol and in water. Their acetone solution is hlue. Anal. Calcd. for C Q H T ~ O S ~ C,O ~55.60; : H, 5.lO5;N, 11.43. Found: C, 55.70, 55.73; H, 5.31, 5.09; S , 14.39. The ether solution from which the white crystals had separated T\ as pumped at 0 ' until most of the ether had been removed and then the residual material was distilled a t 3 mm. Soon after the distillation was started, it was noted that blue liquid and blue solid were condensing in the Dry Ice trap maintained between the still and the vacuum pump. After the distillation was complete the trap was allowed to come to room temperature; i t !vas found to contain about 1 ml. of water, 2 ml. of yellow liquid and about 0.5 g. of white crystals. After filtration and drying, these crystals melted a t 141-143' to a blue niclt with decomposition. Ann%. Calcd. for (C9HloA-203)2:C , 33.60; 13, 5.15; N, 14.43. F O U I I C, ~ : 55.85, 55.73; 13, 5.11, 2.2:); N, 13.91, 13.88. These two crystalline coinpounds are, presuinably, tlie diastereoisomeric nitroso nitro compounds produced by adding hT203 to 1-phenyl-1-propene but, of course, this has not been established.za The isomeric 1-phenyl-2-nitroso(20) A Referee kindly has pointed oiit t h a t one of theqe l i 2 O z adducts m a y tie the nitrosite of a-methylTtyrene.
S , 79
56
~
I'oiind 1%
N
c
l:;, 58
46.73 57.76 57.52
S . 83 10.25 10.28
(i2.ii3
11.11
10.4
0.65
1I.O.i
8.80 8.09
11 ,Wi
~.
N 13.5I 9.87
9.5k s.7:3 8.10
12.01
2-11itropropane ( l - ~ ~ l i c ~ ~ ~pscucloiiitrolc) l - ~ - ~ ~ r otnclts ~ ~ ~a t~ ~ X9-90" (uide injra). (b) From the Reaction of 2-Iodobutane with Silver Nitrite.-The reaction \vas conducted as usual and then tlic silver silts were rcinoved by filtration. The ether solutioii of products, after standing overnight in a refrigcrator, dcposited 0.21 g . of white crystals which consisted of iiccdlei (m.p. 127-129') arid plates (m.p. 131-134'). Both melt to blue liquids. The higher melting form wis analyzed. Anal. Calcd. for (C4H8N203)2:C, 36.37; 13, 6.10; S, 21.21. Found: C , 36.96; H , 6.14; N , 21.3.5. It is noteworthy that 2-nitroso-2-nitrobutanc has m . p . 58-59'.'' In the 2-propyl and the 2-butyl series the nitrite esters and nitroparaffins were removed from high boiling materials by high-vacuum distillation at temps. below 30". I t was found repeatedly t h a t the residual liquids spontaneously decompose on standing at room temperature for a few hours; brown fumes are evolved and dark colored liquids arc produced. Such instability is characteristic of olefin-P\'203 adducts. 22 The Reaction of &Butyl Chloride with Silver Nitrite.115th the small variations the following is rcprcsentative of the experiments employing tertiary halides. Furthcriiiorc, it provides an example of the ultraviolet spectroscopic procedures used to determine the yields of nitrite estcrs (bot11 sccondary and tertiary) which cannot be separated quantitatively from the diethyl ether used as a reaction solvent. The ultraviolet spectrum of t-butyl nitrite in dicthyl ether solution between 300-400 m p is a series of well-dcfinctl absorption maxima. Furthermore, in this region ahsorption is so intense t h a t using a Cary recording spectrophotometer, readings can be made only with colorless solutions of the yellow t-butyl nitrite. However, nitrogen dioxide, nitrogen trioxide and the compounds formed by addition of these oxides to isobutene, all show absorption in this region and conceivably might have interfered with the determinatioii of t-butyl nitrite. Clean separation of t-butyl nitrite from the relatively non-volatile isobutene-oxide of nitrogen adduets was achieved readily at room temperature and a vacuum of 10 m m . But nitrogen trioxide i ~ n diiitrogcii tctroxide cannot be removed from ail ether solution of I butyl nitrite in this way. l~ortunately,a mixture of nitrogen trioxide :tnd nitrogen tetroxide gives ii yellow solution in diethyl ether whose ultraviolet spectrum has absorptioti peaks at 388, 373 arid 360 m p , wave lengths which arc ahsorption minima for t-butyl nitrite. When this yellow solution is diluted until colorless, it has no absorption at 395 tnp, a principal peak for t-butyl nitrite, and there is ncgligiblc adsorption a t the other t-butyl nitrite maxima employed (379 and 365 m p ) . As a further precaution against thc possibility of interfereme, plots of absorbance us. concentration were made for diethyl ether solutions of pure t-butyl nitrite using the absorption maxima a t 365, 379 and 395 m y . Since in subsequent determinations of t-butyl nitrite in rcaction products tlie concentrations givcri by using t h , w tlirce plots wcrc the same, it is cxcerdingly unlikely t11at tliere was any interferencc. In the cvcnt of interfcreiicr the three peaks would likely have been displaced by differrnt amounts, and thus readings at the three different wave lengths would have given three different concentrations. ._
( 2 1 ) E . Piloty, Bo.., 3 5 , 309.5 (1902). (22) N. Levy and C. \V. Scaife, .I. Cheiii. .Soc., 109% (1946); hlirhael a n d G , H. Carlsnn, J . Ovg. C h e m . , 5 , 1 (1940).
A.
REACTIONS OF ALKYLIODIDES WITH HALOGENS
Nov. 5, 1955
A slurry of 100 g. of silver nitrite and 250 ml. of anhydrous ether in a 500-ml. three-necked flask fitted with a drying tube, dropping funnel and glass paddle stirrer was cooled in a salt-ice-bath and 46.25 g. (0.5 mole) of t-butyl chloride was added dropwise over a period of an hour. After stirring a t ice temperature for a total of 28 hours, the silver salts were removed by filtration, washed with ether and the washings were added to the green filtrate. The ether solution of products was placed in a flask fitted to a 4-ft. glass helix packed column, the column head being cooled by circulating brine and set for total reflux. Two Dry Ice traps were placed between the head of the column and the vacuum pump. Without application of heat, the pressure was reduced to 200 mm., then to 50 mm. and finally to 10 mm. and distillate was collected until it started to freeze in the first trap as it came over. (The material which had not distilled amounted to 10.53 g. of a blue liquid; it was treated as described below.) The distillate, consisting of ether and nitrite, was diluted to 500 ml. with ether and one ml. of this was further diluted to 50 ml. From the absorbance at 365, 379 and 395 mp it was found that 32.7 g. of t-butyl nitrite (64% yield) had been produced. Rectification of the diethyl ether-t-butyl nitrite solulioiis manifestly failed to give complete separation. The ether distilling off was yellow and i t had a distinct odor of t-butyl nitrite. Despite this, there was obtained 20.8 g. (40% yield) of t-butyl nitrite, b.p. 63", n z o D 1.3687.
[CONTRIBUTION FROM
THE
5533
The 10.53 g. of blue liquid left after t-butyl nitrite and diethyl ether were removed from the reaction product (see above) was diluted with an equal volume of 35-37' petroleum ether, washed with water, then with 10% sodium hydroxide until the aqueous layer remained colorless, then with 85% phosphoric acid, and finally with water. After drying over anhydrous magnesium sulfate, the petroleum ether solution was distilled. This gave 2.2 g. (4% yield) of t-nitrobutane, b.p. 125-127', T Z ~ O D 1.4022; lit. valuesz3: X ~ 1.4015, D b.p. 126". Duplication of this experiment, except for the addition of 100 g. of Drierite to the reaction mixture, gave a 63% yield of I-butyl nitrite and a 5% yield of t-nitrobutane. I-Phenyl-2-nitro-2-nitrosopropane ( I-Phenyl-2-propyl Pseudonitrole).-An aqueous alkaline solution of l-phenyl2-nitropropane containing sodium nitrite was acidified with hydrochloric acid. The product was taken up in diethyl ether, the blue solution was washed with water, dried over anhydrous magnesium sulfate and placed in a refrigerator. The white crystals obtained were recrystallized from a mixture of acetone and ether; m.p. 89-90' (to a blue liquid). Anal. Calcd. for CsH10N203: C, 55.60; H, 5.15; N, 14.43. Found: C, 55.81, 55.6s; H , 5.26, 5.33; N, 14.65, 14.28. LAFAYETTE, INDIANA (23) R . H . Wiswalland C. P. Smyth, J . Cizem. P h y s . , 9 , 3 5 6 (1941).
DEPARTMENT O F CHEMISTRY OF THE
POLYTECHNIC
INSTITUTE
OF
BROOKLYN]
The Reactions of Alkyl Iodides with Halogens1 B Y F.
hfARSL4LL
BERINGERAND HERMAN s. ~ C H U L T Z
RECEIVED APRIL 7, 1955 Optically active 2-iodooctane reacted with chlorine or with bromine in a cold inert solvent to give as a main product 2chlorooctane or 2-bromooctane of predominantly inverted configuration. Similar reaction with iodine monochloride yielded predominantly inverted 2-chlorooctane, optically inactive 2,3-dichlorooctane and an optically inactive iodochlorooctane.2 Under similar conditions neopentyl iodide reacted with chlorine and bromine to give I-amyl halides and the halogen adducts of trimethylethylene. Possible mechanisms for these reactions are discussed.
Introduction peratures6 and which exist in appreciable amount Currently it appears that there are three mech- a t room temperature.8 anisms by which alkyl halides can exchange with TABLE I free halogens. First, exchange may be initiated REACTIONS O F OPTICALLY ACTIVE2-IODOOCTANE: R = 2by iodine atoms produced thermally or by photolyOCTYL s k 3 With allyl iodide another mechanism is apReaction Conditions RI RXa ki/krb parently operating, namely, coordination of molecR I + Clz 1:l HCClsd4 1.3164 (26') 0.8663 (26") 6.0 ular iodine with the olefinic bond followed by loss pet. ether, of a different pair of adjacent iodine atoms.4 70.67, -78', 1.5 ? Z D 1.4877 (22O) 1.4251 (24') hr.; Oo, 1.5 hr. Finally there seems to be a third, non-radical path [a10 +46.33 (26') -24.93 (26') available for exchange with chlorine, bromine or RCI $. IC1 h.p. 94O (16 mm.) 61' (14 mm.) iodine mon~chloride.~-~ I t has been suggested' X D 1 4782 ( 2 6 O ) 1.4224 (23') 2.1 that these last exchanges proceed through the for- R I + IC1 CCla, 2 5 O , 74 hr. mation and breakdown of alkyl iodide-halogen 1 33.4S7oe [ a ] D -45.47 (28") f 1 2 . 4 (24") complexes, which may be precipitated a t low tem- RCI + 11 b.p. 93 O(16 mm.) 6 4 O (16 mm.) (1) This paper is taken from the Ph.D. dissertation of Herman S. Schultz, June, 1956. The reaction of optically active 2-iodooctane with chlorine t o give 2-chlorooctane of inverted configuration was reported earlier in the B.S. thesis of David Goland, June, 1951. (2) The conversion of optically active 2-iodooctane t o Z-chlorooctane of inverted configuration has been independently confirmed recently: E. J. Corey and W. J. Wechter, THISJOURNAL, 76, 6040 ( 1954).
(3) For leading papers see R. M. Noyes and D. J. Sihbett, ibid., 76, 761, 761 (19,531. (4) D. J . Sihbett and R . hl. Noyes, ibid.. 76,763 (1953). ( 5 ) A. Geuther, A n n . , 123, 124 (1862); C. Friedel, ibid.,136, 206 (1865); F. Viebock and A. Schwappach, Ber., 63B,2818 (1930). (6) J. Thiele and W. Peters, ibid., 38, 3842 (1905); A n n . , 369, 149 (1909). (7) R . hl. Keefer and L. J. Andrews, THISJ O U R N A L , 75, 543 (1953); 76, 253 (le%).
RI
4
+ BrP
Pet. ether,
85%d
-78', 2
RBr
+ IBr
R I f Bri 55%d RBr IBr
4
+
"4
XD
1.3157 (27O) 1.4864 ( 2 5 ' )
1.1010 (26') 1.4485 (26")
3 5
hr. O o , 1 hr.
P e t . ether, 2 5 O , 5 hr.
[ a ] D +45.0 (27') b.p. 9 5 O (17 mm.) nn 1.4857 ( 2 6 O )
[ a ]f 4 ~5 . 7 (25O)
b.p. 72' (5 mm.)
-21.0
(26')
79' (17 mm.) 1.4492 ( 2 5 ' ) -15.4 (25') 71' (16 mm.)
2.3
X = CI in reactions with Clz, ICl; X = Br in reactions with Br2. bSee definition and discussions in footnotes 9 and 10. For other products see Experimental section. Yield was obtained with dl-2-iodooctane.
A t the inception of this work in 1950, i t was felt that useful information might be obtained concern(8) R. M. Keefer and L. J. Andrews. THISJ O U R N A L , 74, 1891 (1952).
