A Study of the Unsaturation of 2-Bromo Butane Citation Simpson, Thomas Patrick (1925) A Study of the Unsaturation of 2-Bromo Butane. Bachelor's thesis, California Institute of Technology. doi:10.7907/q12t-z316. https://resolver.caltech.edu/CaltechTHESIS:08082024-161604927 Abstract No abstract. Item Type: Thesis (Bachelor's thesis) Subject Keywords: (Chemical Engineering) Degree Grantor: California Institute of Technology Division: Chemistry and Chemical Engineering Major Option: Chemical Engineering Thesis Availability: Public (worldwide access) Research Advisor(s): Unknown, Unknown Thesis Committee: Unknown, Unknown Defense Date: 1924 Record Number: CaltechTHESIS:08082024-161604927 Persistent URL: https://resolver.caltech.edu/CaltechTHESIS:08082024-161604927 DOI: 10.7907/q12t-z316 Default Usage Policy: No commercial reproduction, distribution, display or performance rights in this work are provided. ID Code: 16621 Collection: CaltechTHESIS Deposited By: Benjamin Perez Deposited On: 09 Aug 2024 17:20 Last Modified: 09 Aug 2024 17:30 Thesis Files PDF - Final Version See Usage Policy. 7MB Repository Staff Only: item control page

A STUDY of the UUSA11URAI 1 I ON 03' 2-BR OMO BUTANE Thesis by Thomas p. Simpson In partial fulfillment of the requirements for the degree of Bachelor of Science in Chemical Eng ineering. CALTJ'ORNIA INS 1rI 'rUT E OF TECHNOLOGY Pasadena, California. I. INTRODUCTION Although the unsaturation of secondary butyl iodide has been mentioned in the literature { I) no details have been given about the method of procedure or the quantitative results. It therefore seems desireable to further study the unsaturation of secondary butyl halides, and in this particular case 2-butyl bromide.** When 2- butyl bromide is unsaturated two butenes may be obtained as is illustrated by the following reaction. The problem which concerns the author consists in dete~mining the relative proportions of these butenes formed. The unsaturation of 2-butanol offers the same p:g;s,sNi':ii]lti'es and a problem of similar nature. (2)' Evers has studied this problem, by unsaturating 2-butanol with phosphorus pentoxide and finds that 2-butene is obtained without even a trace of I-butene. **Note. 2-bromo butane is the correct nomenclature and is ±ntended wherever 2-butyl bromide occurs in this thesis. 2. OUTLINE OF PROCEDURE Inorder to determine the relative proportions of the I-butene and 2-butene obtained by the unsaturation of the 2-butyl bromide it was deemed advisable to add chlorine to them thus giving I,2-dichlor-butane and 2,3-dichlor-butane respectively. It is better to form the di-chlor rather than the di-brom compounds because they boil about 40• lower and can therefore be distilled with less danger of decomposition. In addition the chlor compounds are usually more stable than the brom. However the literature gives only meager and inconsistent data concerning the di-chlor compounds. It therefore seemed desireable to prepare them by synthesis and make a thorough investigation of their properties before proceeding with the unsaturation of the 2-butyl bromide. The first method decided upon to prepare the 2,3-dichlor-butane was to proceed through the following reactions. +C 2H5 Br CH 3 CH(ONa)COOC 2H5 + HCl ► CH CHC1CHC1CH 3 3 This method of attack was abandoned after two attempts to prepare the ethyl lactate by the method ( 3) of Gustrow failed to give satisfactory results. The next method of attack decided on was to bgo through the following set of reactions. +HOH CH3 CH(OMgCl)CH(OC 2 H5 )CH3 +HCl CH CHOHCHOHCH 3 3 +HI ► CH3 CHOHCH(OC 2 H5 )CH3 ~ This method was abandoned after two attempts to prepare chlor-ethyl ether by the method of Gauthier( 4 ) failed to give a suitable yield or a produet free from acid and water. The next method was ~o prepare 2,3-di-hydroxy butane by the method suggested by L.Meunier C5) using magnesium amalgam and acetaldehyde. When the first attempt failed to give the results predicted a second was about to be made when it was found that more recent 6 investigators( )had disproved the work of Meunier. This method was therefore abandoned. An attempt was then made to prepare I,~-di-chlor butane by unsaturating normal butyl bromide with alcoholic potassium hydroxide and then adding chlorine to the COW1fQOc.ff"ld butene thus obtained. However no di-chlorAwas obtained but a 63% yield of butyl ethyl ether was obtained. Finally it was decided to determihe the produits of unsaturation of the 2-butyl bromide by forming the di-brom rather than the di-chlor compounds. The properties of I,2 di-brom and 2,3 di-brom butanes are well established and since all investigators ( '7) seem to agree,it is justifiable to use their results without , further investigation. 1his method yielded satisfactory results. In addition one run was made adding chlorine to the products of unsaturation,and the results of this test checked those where bromine was added. OUTLINE 01P CNNCLUSIONS. By inspecting the results obtained in the fractionations as well as plots I and II made from them, it is evident that only the 2,3-dihalogen butanes are obtained by adding halogen to the products of unsaturation of the 2-butyl bromide. This implies that only 2-butene is formed in the unsaturation and completely eliminates the possibility of any appreciable amount of I-butene being produced. T!is is a just conclusion because throughout the entire procedure of fractionation there was never any indication of the presence of a compound having a boiling point corresponding to those of the I,2-dihalogen butanes. These results also establish the boiling point for the meso form of 2,3-di-chlor butane as " 0 at 745m.m.,and the racemic probably as II5.5-II6.5 0 • 0 II8.0-II9.0 at the same pressure. the results of Scheschukow ( 8) These figures check 0 0 who gives II5-IIO. for the boiling point of 2,3-di-chl~r butane. EXPERIMENTAL PART. The 2-butyl bromide was prepared by treating 2-butanol (obtained fro m the standard Oil company of New Jersey,)with hydrogen bromide. Hydrogen bromide prepared by treating sodium bromide with concentrated sulfuric acid,was passed into the 2-butanol until an excess of 251~ over the theoretical amount necessary to react with it had been added. This mixture was then 0 heated under pressure on a bath maintained at 65.-75. for about ten hours. The 2-butyl bromide thus prepared was washed several times with water and dilute alkali, and then dried. The crude dry product was then distilled. (I 0 The fraction distilling at 88.0-90.5(uncorrected) was used uclusively in all the succeeding experiments. The yield was 7C/fc of the ,theoretical. The apparatus used for the unsaturation of the 2-bu tyl bromide and for adding bromine to th e , . unsaturated compounds obtained,is shawm in Figurer. The butyl bromide is unsaturated by dropping it from the dropping funnel C through the dropping tube B into the reaction chamber A containing a strong alcoholic potassium hydroxide solution. The • chamber A has a volume of 300c.c. and is surrounded by 0 O an oil bath at I20.-I40 •• The butene generated by the reaction boils 0 • at tI to -5 and is therefore gaseous at room temperature,and passes through the condenser D surrounded by tap water,t;hen through the tube E into the tube F which contains a little water to wash out the aicohol. The gas then passes through the drying tube G containing calcium chloride,and then through the tube H surrounded by a bath I maintained at 0 0 2.5-5.0. The tube H serves to precool the gas and to condense out higher boiling:..~substances in it. '.Phe gas then passes into the chamber K containing bromine and here the butene reacts with the bromine to form the dibrom compounds. K is surrounded by a bath L maintained at 0 about -5.0 at the start of a run ,the temperature being gradually lowered as the amount of dibrom compound increases, until the minimum. -pessible temperature obtainable with a mixture of ice and sodium chloride is reached. Thus K serves as a reaction chamber,and a condenser for the butene. Bromine is introduced into/ K by means of the funnel J . Mis surrounded at all times by the bath N containing a mixture of ice and sodium chloride at the minimum possible temperature. M serves to condense out any butene that escapes reaction,and acts as a safety trap between Kand o. O contains carbon tetrachloride and acts as a pressure gauge to 4/so indicate how the apparatus is operating,-itAdissolves any bromine that comes over and prevents it from escaping into the room.Pis empty and is open to the atmosphere, it serves as a catch-all in case a sudden pressure increase should spurt some carbon tetrachloride out of o. In the case where chlorine is added to the butenes,the chamber K is replaced by a large u tube with arms about 40.cms. long and a bore about 4cms •. This is kept as cold as possible ,with an ice and sodium chloride freezing mixture ➔ throughout the entire procedure. After the reaction in A is complete air is drawn slowly into the apparatus by applying suction at P and openi~valves C and B. A little water is also introduced into A to reduce the solubility of the butene in the alcoholic potassium hydroxide. In this manner most of the butene is condensed into K or the large u tube as the case may be,and the losses are minimized. In the case where chlorine is added,after th J butene is all condensed the apparatus is separated ·oetwee.n G and H, and H is shut off from the a t mosphere. Dry chlorine is then introduced through one side arm of the large U tube containing the butene. The - chlorine is introduced at the rate of 40 to 60 c.f. per minute, but in any event :5fte it should not be introduced more rapidly than it will be absorbed. The reaction is complete when the liquid obtains a ye l low colori,and the flow of chlorine is then shut off. It takes about 3 hours for a run beginning with 50 grams of 2-butyl bromide when bromine is added and from 6 to 8 hours when chlorine is added. In either case the crude di-halogen butane is washed with I to 3 normal sodium hydroxide solution to remove excess halogen, and then with water. rt is then dried with calcium chloride and is ready for distillation. The distillation was made with an Eastman fractionati'ng column about 25 ems. high. That part of the liquid which could not be distilled with the cmlumn was removed to a small flask (about I5 c.c. in volume) and repeatedly fraction$4ed. Three runs were made adding bromine and one run addll.ng chlorine to the butenes obtained in the unsaturation. The results of the bromine runs are as follows: Ist run 2nd run Weight of 2-butyl bromide used /.37 50.0 50.0 " hydroxide used "lt potassium '/3 v'is"-.-''>\.,J ,,,.,\_"it, 60.0 60.0 80.0 " If crude,dry c H Br obtained 4 8 2 35.2 35.0 9I.3 Yield " " 44.'7% 44.5% 89.0% 'I " " If 3rd run *Note.The weights in the above table are in grams. The alcoholic potassium hydroxide consisted of 2 parts by weight,of potassium hydroxide, to 3 parts by weight of 96% ethyl alcohol. It will be noticed in the above table that for each mol of potassium hydroxide there are approximately two fifths of a mol of 2-butyl bromide. The yields are low in the first two runs because the apparatus had not been perfected and accidents occured which caused much of t he product to be lost. However the third run is representative and the apparatus used (Fig. I ) eliminates the possibility of the losses which occured in the first runs. !t l., ~ J~ 9 Wislicenus( ) gives the boiling point of 0 the meso form of 2,3-dibrom butane as I58 and that of 0 the racemic for rn as I6I. All authors agree with these figures,and none have been found at variance. Furthermore all authors ( '7 ) seem to agree on the boiling point of 0 O I,2-dibrom butane as I65.6 - I66.0 . rt is well t, to keep these figures in mind while inspecting the following tables. The products of the first two runs were combined and fractionally distilled. The fractionation was repeated about six times. ~he results of the first and last fractionations are as follows: First fractionation. Weight of fraction I56.0 - I5 '7. 5 corrected '746m.m. " " " I5'7. 5 I59.0 " " " " II I59 .O II I62.0 " I'75 Jlus residue II " 3.0 60.0 - I62.0 " " " " - I'75.0 " II " " II ?-0 " 58.0 4.0 r.o r.o Ba.st fractionation. Weight of fraction I56.0 - I5 '7. 5 " " " I5'7.5 I59.0 II " " I59.0 - I60.5 II II 0.6 " II " I60.5 I62.5 II 6.0 If II II I62.5 I'70.0 " " " " IT I! I'70 plus residue 0.4 ) 0.5 ._, -,I •. ·.:. \'~ /J. The product from the third run was fractionated the same as the first runs. the results of the first and last fractionations are as follows: First fractionation. Weight of fraction up to I56.0 " " " " " " " " " " " corrected '746m.m. " " " I56.0 - I57.9 " " r.o 4.3 75.2 I57 • 9 - I58. 9 " I58.9 - I60.5 " If " I60.5 - I65.0 n 2.0 ll I65.0 - I75.0 " " " 2.6 I.5 "residue Last fractionation. corrected 746m.m. Weight of fraction up to I57 .O r.o :'~ " " " " " " " " " "" I57.0 .; I57.9 I57. 9 - I58. " I58.9 I60.5 " " I60.5 - I6I.5 " II " " " " " " " residue " " II II I6 I.5 9 4.0 " i, (o " " i. " " 68.0 " 0.7 " Tl -~--- ~-- - -- ....·i- i- -=--0 , n 2.3 II " o.-6 " " 0.2 'i ~, :t, , - I63.5 'l <" • f ·' I63.5 - I65.0 . ) I65.0 - I6'7.0 " I67.0 I'75.0 " * NOte. The weights in all tables are in grams. 0.6 r.3 -------~ - - ·----· . ~ rt,t1 1, 0 I j ----- Iii/-. 1-1-J..l-illlJ_I- J tt t:i: l r n I :fl} .,. T -1- t .,. rH-t-t-t-t-t-i·H# /RAC 1l1 I ONA'f I ON j i .. -+i ' l tI I- t I ...t __ ttrn:ttffitl:ffitftif_lJt--lW.JrJ0Jffftffmf.t.ffiE=mt- l 11 j rr ·tI l l t- -ISfJ I ·t- f 11: I ,. 7 The results of the chlorine run are given in the tables below. The fractionation was made in the same manner as in the bromine runs,and about the same number of times. 27.0 Weight of 2-butyl bromide used " " Yield " " " potassium hydroxide used 34.0 crude,dry c H c1 obtained 4 8 2 20.0 n 80.5% " " " This yield is smaller than that obtained in the third run using bromine because the arn ount of substance used is much smaller an d the losses i n the apparatus produce a much greater effect. The results of the first and last fractiona.tions are as follows: First fractionation. Weight of fractio n rro.o - II5.5 corrected 745m.m. !.9 " " II5.5 - II'l.5 " " ro.o II'l.5 - II9.5 " 4.0 1f II9.5 - I24.0 " 124.0 - I50.0 " " " " " " " " " " " " " " " residue • r.o r.o r.o *Note. The boiliny goints of I,2 and 2,3-dichlor butanes are given as I25°. I ) and rrf 0 - I20~ 8 ) respectively. H -1 - H- f_ I -,-L 1-i + -Ht-t,l+H-1 H ' t -~ 1-~• :·. ' '"++f,+H-H-f-+++-Hf+ij+-f+++,+f++-L c · > 1i--1-f~--l--l--~J-1-1 J 2.0 -,. l-+++-tttttt·.::ttt + " + t hf--,- ·--::ttttttiit~.t=tttt1:1::t:1+mm i /.J -!",: ~~¥m#l:R=f:lm+~+ijtl1ll-+tt·e~ +m-+++1-l+H-!ft_+FFFffffl:t 1 rt-'f-l--l-l.-l-+l--1--1--1-1--1 • --H+H-H+++-H+++H,H-++++H-H+I-H--l-~>-,-,1- .. t ;- 1-- 1-t++l·Ht·H-l+·t+H 1 hj ! , f c:: -H±Jl-B+-H-H+H-f-H-f+mH=++.J+H-h:crl++mH--4-h-t+J:1 t+t+±l:n±H:H+ttH-Htl±l:Hff±" ..:. 1 1+1-Cr-W--,•• ,_,_ el-e-1-+-i~l--l-P-l -• i ; ~tt + -t ! I ,_ .,. ... H --1-<- !_ 1 ! ·- Last fractionation. Weight of fraction rro.o - II5. 5 • Actual values. Corrected values. r.s I.5 " " II II5.5 - II6.5 s.o I0.3 II II " II6.5 - II7.5 2.8 3.6 " " " II7.5 II8.5 r.4 r.s " II IIS.5 I22.5 r.o r.3 ,, " " I22.5 - !30.0 o.s 0.4 " residue o.s - ---~--- -- _____....,.,. " II r.o i ti' Cf *Note. All temperatures in the above table are corrected The column of corrected values is derived to 745m.m •. from the actual values by distributing the loss due to fractionation proportional to the size of each fraction. Plot IIis made from the corrected values. The results of the attempts to prepare the ethyl lactate are as follows: First batch. Weight of 90% lactic acid used " "96% ethyl alcohol used 220. gms. I60. Half of the alcohol was first saturated with hydrogen chloride and then the entire batch was mixed together. " Second batch. Weight of 90% lactic acid used " " 236. gms "96% ethyl alcohol used I70. " "Concentrated sulfuric acid used 80. " Both batches were allowed to stand for two days and were then refluxed for about ten hours on a water bath. The mixture was then distilled using a fractionating device until the temperature of the distillate coming over r~ached roo~ Then distillation was then continued under a pressure of 25m.m •• The major ~ 0 portmon of the distillate then came over between 35 and 45°and consisted almost entirely of alcohol and water. The residue remaining in the flask seemed to be a mixture of lactic and mineral acid and no evidence of ethyl lactate could be obtained. Further fraetionation of the lower boiling fractions did not yield any ethyl lactate. Although Gustrow( 3 ) claims to have obtained a good yield of ethyl lactate by treating lactic acid with ethyl alcohol in the presence of mineral acid, the author was unable to do so because Gustrow's outline of procedure is only general and lacks the experimental details necessary for successful execution. The results of one run in t the preparation of alpha-chlor ethyl ether by the method of Gauthier( 4 ) are as follows: Weight of paraldehyde used I06. gms. " " absolute ethyl alcohol used I04. " "hydrogen chloride used , IIO. " " The paraldehyde and alcohol were placed in a pressure bottle surrounded by a freezing mixture of ice and sodium chloride; the hydrogen chloride,generated by dropping concentrated hydrochloric acid into concentrated sulfuric acid, was then introduced. The bottle was then close d and allowed to stand for about two weeks. The mixture was then distilled using a Hempel fractionat i ng column about 35 ems. high. Ab0ut 30. grams 0 0 of distillate boiling at 95 - IOO was obtained, - this being the chlor ethyl ether which has a boiling point 0 about 98. This is a r5%yield. The product obtained could not be freed from hydrogen chloride,aldehyde or alcohol because it decomposes quite rapidly into these substances even in the cold. Consequently it could not be used in the subsequent procedur e . SUM.MARY I. 2-bromo butane was unsaturated by means of po;assium hydroxide. 2. Bromine was added to the unsaturated compound produced by the unsaturation in one c ase while chlorine was added in another. 3. Only 2,3-dihalogen butanes are obtained by this procedure, thus proving that only 2-butene is produced by the unsaturation of 2--bromo butane. 4. The boiling point of the meso form of 2,3-dichlor butane has been established as II5.5 • - II6.5 • corrected to 745 m.m. 5. A suitable apparatus has been described for unsaturating 2-bromo butane,and for adding halogen to the butene thus obtained. BIBLIOGP.APHY. (I). De Lynes. A. I29,200; I32,275. Lieben. A. I50,I08. ( 2). Evers. A. 390,238 . (!~i'),1 (3). Gustrow. (4). Gauthier. A.Ch. (8) I6,3II • (5). L.Meunier. c.r.d.l'Acad.des sciences I34,472. (6). Tischtschenko and Grigorjew. c. I906,II-470. " " c. I906,II-I556. woronkow. c. I906,II-I556. Kling and Roy. c.r. I44,IIII(I907) " " " • " (7). 1---Wurtz. A.I52,23; I44,236. ,>Linneman. A. I6I, I99 • ~Berzfelder. B. 26,I260. ')-ii.•·/: ( Reboul. Bl. (3) 7,I25, qO ~ - , i) Carius. A. I26,2I5. V.Meyer,M~ller. J.Pr. (2) 46,I8I il t~~) vFaworski. A. 354,372 ; C.I908,I-I04I. ( 8). Scheschukow. ·3 • I7 J I509 \/ /i/Y.~·; ' 111,,VY ., 0f)i,,1Nl-O, (!J~ t/ I / • · C'1.e,w o • ~.u-·0 , 'J V. Meyer,Muller. J.Pr. (2) 46,I86 ( 1iq ~) ( 9) • Wi .e ll ~enus,Talbot,Henze. C.I897,II-26I; A. 3I3,24I (IO). ( C.I9I2,II-I2I2 • ) *Note. Abbreviations correspond to those in Richter or Beilstein. t • .___.___,__,._,.eo'..J.__:_--1-_i--;....-+---+__l,_+--+.-:..-1----+------1---+--r-;-___,, ~ • l----l--~ ~~L--4------+--r--+--+----,1---+--------.--,---r---. --+----1 0 1---1-.-...:~--l----l-~ i!.O U-'-£.LI-~~..,~ - - ~ & ~ +---+--------i l-----t-~~---t---l---+-----1---l----+-~-,---:.--t---t--t----r---J 1 ] --1-----1------+-,----t-----1 ~) ---- + . ' ' I ,, J I t i I, ,l ri 11- I• ~ I .-. I -rioc11oncifV1st!/ofion ol ~1RBt; - r 1 I I - .' 7() . l . 0 ,_ ' i - . • ·- l I I - ~ • ' t + 1 - , . l . I ' I I' I I ' . I I ·- l I (,. I ; : .l - --+ j ,) I ' . it I I I I - .. ' • f: ~ .. ~ 1 ~ ,,~• '(.J I I t ' j '> i I I ,, I t I - ,.I , I . .,. •• I - . .6 ~ ~__.,~ :, - - -- - - - -- - - . -- - I I I I - ,7'(F'" - ~ l f . , __ ~ I I I ' I I . 11 I ~ I t T ,. . I I l ' 1 r ' f L ),, C 0 l!O r.; t ,-1. -e.. -·, J I 40 60 /00 8'{) !!J -.st .'rl/7d SeirOLZ._F rs -~ 0d J?rJ -0 T/;j - I ,tt194'r e r • I d_ +-- -" . ---- - I ' To ,ro/ v_;'rt:~m,c;- nr Di:~ lfil;ofe ~ :, I ' ,sn ~ ·- . t f t I ' - - I j -