Air Entrainment in Gas Burners G . l o \ ELBE % \ D J. GRCMER Crntrcil E . ~ p e r i m e n Stution, t
t . S . Bicreazc of Wines, Pittsburgh, l'u.
Air entrainment in burners with ctlindrical tubes can be calculated on the basis that part of the stredin nionientum is transformed into static pressure corresponding to the flow resistance imposed bj friction, buolancj, and flame thrust. Satisfactor? agreement is found with experimental data. When the flame is to be distributed over a number of port oljenings, Tenturi ducts are required. The energy loss in a l enturi duct has been studied by separate11 measuring the potential energ?, the kinetic energ? corresponding to abetage Telocitj, and the kinetic energj contributed b> the telocity profile. I t has been concliided that hetween theTenturi throat and the burner head, the latter contribution is lost in the form of eddy motions.
T
IIE problem of priniary air ciitraiiinieiit ill atinospheric gas hurners has been treated in many publications oi the S a ti(iii!al Bureau of Standards and the dmerican Gas .issociatioti 'J'ttiting Laboratories (2, 5, 5-7, 11 ). The factors of the burnei tlwigii 11-hich have been studied comprise: the slope, length, atid t h a t tliaineter of the Venturi tube, shape of the Venturi inlet, hend. in the Venturi tube, tlie total port area, the geometrical tlesiyii of the burner hcad, the size and depth of the portholes, i t i t w i d surface conditions, primary air inlets, orifice position, and f fuel gas that have been studied comprise: q w i f i c gravity, licstiiig value, pressure, and burner temperature. Tht' air entrainment has been represented in general hy a n cquati1111of tiic form ,Stream momentum at orifice = k
x stream nioinentuiii a t port
ILerctiie coefficient f; is empiricallj- cleteriiiiuetl a' a function of t h e :xhove variables. The hasic units of mass and velocity are customarily converted t o units of gas pre;sut'e, heating value, :iieiific gravity, and burncr temperature to meet tlie needs of the gac eiigineer. The validity of these relations is necessarily reh t i , i ( , t i d and it is desirable t o obtain a closer theoretical insight i t i t o t 1 i o process of air entrainment. IIorcover, it appeal's that .teiii:itic data on air entrainment are available only for burners I t \-enturi ducts and tliat, escept for data on flash tube perfiirtixtnw (4) which are not applicable here, n3 systematic data 011 ryliiidrical burner tubes are available. Ttii. paper deals n.ith burners consisting of a free gas jet in air aii(1 vitlier a cylindrical burner tube or a 1-enturi duct ivhicli lead. t o :i iiianifold of sinall flame ports. C Y L I S D R I C i L BGRSER TUBES
1 illustrates the theory for burners of this type; similar tions apply t o air injection ventilators (16, 13). The m forms n free jet betneen tlie plane. 0, of the orifice an( mine plane, .c, antl the stream cross section espands due t o air. enti:iinnient fl,om -1, at tlie orifice to -1,in planes. that ttic niisirig pmccss is completed in plane z and teiiipcuture docs i i ~ tchange appreciably along the duct, then, liecausc, ilie gas ma>- lie treated as an incompressible fluid, the density. p , and tile volumetric flon., i-, of tlie gas-air mixture rtwiaii; constant ironi plane x on t o tlie end o i the burner tube. Tlie static pressure :vitliin the free jet is the same as that of the surrountling atI11oslllicr but doi\-ii3tremi iroin plane x tlie static prei,ure must i n utiril it is sufficiently come the n-all fi.ictioii tube aud the back p flame. This can only rixiie about hy a decrcaze o a i d correjlioiidiiigl!-, the strc:m cross section crpands bctrreeri plane TC and some 1'1 tit from -1, to tlie full CI'OSS section, 1, o f thc. tube with a rease ot tilt. average gas velocity from 1123
17/Azto T.,'.t. In other words, bet~r.i.etiplants s aiid )ti the g;tx velocity profile is redistributed o ~ e the r arm, A. In this p r i m v sonic stream energy i.; lost i n the form of orldics ( 9 ) . m attains the m~iximuixis:atic prwaurc / J , ~ Tlir force ncliiig iictn-ceii planes I I I arid c. ~ C S S U ~.1i 1E plane .zis evidently atmosptiwic . This force is c,:lunl to the l o ~ of s monit~iitun1 per unit timc hrtn-cen x and u-tlitit is, A p , = I , I deIi(Jtrimental gas percentages coincide in the laniinar flon- range and almost coincide in thv turbulent, range as predicted by Equation 3 and the friction 1;yuations 5 and sa. When the burner posiiiori is changed or when the burrier is lighted, the difference of the t u t x arcas comes into effect ncmrding to €;quation 3 and the flame pr ure and buoyancy equations, 7 and 8, and the calculated cur! arid espcrimental points diverge (Figure 6). For the curves of Figure 4, 1, \vas chosen as 1 and t o as 0.83 for the smaller and 0.93 for :he larger orifice. These values do not allow a good representation of rlie data for the shortest burner tube (curves A-3 and B-3). ,4close fit for all three burner lengths can be obtained by lorvering the value of b o for each orifice and asuniing large values of L , ~for short tubes and small values for long tubes. For example, by using t o = 0.86 for the larger orifice and t m = 1 for the short burner tube the curves B-3 become curves B-4 which fit the experimental data closely. For the longer tubes and the same orifice, the values t o = 0.86 and im = 0.85 yield well fit,ting curves similar t,o curves B-1 and €3-2. The 1.580em. burner in Figure 5 seems t o require a large value of L , ~ namely, for i n = 0.86. tm = 1-particularly in the t,urbulent region. This may be attributable t o more uniform velocity distribution in turbulent streams. I n short and wide tubes jet turbulence persists more than in long and narroTv tubes, so that the assumption of large values of trn for the former may have some physical meaning. The effect of lighting a burner consists in decreasing the air entrainment, corresponding to the magnitude of the flame pressure (Figure 2). This is illustrated in Figure 7. The diagrams also s h o r the range of stable flame bounded by regions of flash back
Figurc 4 sho\vs calculated curves and esperiniental data for unlighted burners in various positions. The flon- through the h r r i e r tube is generally considerably bclo\T the critical Reynolds riunibcr and p , is tlicwforc calculated for laminar flow. This assumption is not strictly valid because some jet turbulence persists for an appreciable di3tance down the tube, particularly in short tubes and at high gas velocities. On the other hand, this is somewhat compeiisatttl by the fact that under such Upright position , Dohnrigit po!!tjon' Burrer not ltghted Burner lighted ' ' c~~nditions the contrihutioii of friction is smallest. The curves 14 f i ~ rupright burners pass through a niasinium l w a u s e of the opposing effects of buoyancy and friction. In tlonnriglit tiurners buoyancy and friction augment each other: this 8 12 rmults in lower air entraiument-that is, in highel, pa? pcrvi W centages-than for horizontal burners n-hert only friction is -I acting.. K i t h increasing gas flow, the .wcontl tern1 oi Equad 10 3 tion 3 vanishes for the laminar case but not (Equation 5a) z z for the turbulent case. Correyxmdingly: for flows near the 8 critical Reynolds number of 2200. t h e (~spc~riniental gas pcrctntages are higher than the tlicorrticnl. particularly for long tubes v,-here friction matters nioit. T h a t this may be 0 20 40 0 20 40 0 20 40 60 attributed t o the transition from prcdoniinant1)- laminar t o NATURAL GAS FLOW CUBIC CENTIMETERS PER SECOND turbulmt flow is further slion-n in Figure 5 hy the manner in Figure 6 . Effect of Nonhoriaontal Position and Flame which the experimental points follow or d w i a t e from the curves calculatcd for tlic laminar ant1 the, turbulent c a w Same burners as in Figure 5 . ('alculated c u n c s and expenmental points ~
&I
1126
21 0
INDUSTRIAL AND ENGINEERING CHEMISTRY
'
I
I
,
I
I
I
1
1
40 0 20 40 0 20 NATURAL GAS FLOW CUBIC C E W M E T E R S PER SECOYD
20
Figure 7.
40
60
Effect of Ignition on Air Entrainment
Calculated curves and experimental points
and blo\voff (fi]. In the case of upright position and 68.1 cm. burner length, a part of the entrainiiient curve for tlic uiiignited burner lies within the flash-back region. The flanie pressure shifts the entraininent, curve out of this region. Hexicr, if an attempt is made to light the burner at a flovi 11-ithin the fl region, flash back results; on the other hand, n-hen die burner has been lighted at some higher flow i t can be throttled to the same loivc~rf l o ~without flashing back. 1 1 1 exaniplc of particularly untavorable burner characteristics is shon-ii in I.'igure 8. The st,ahle-fiaine region is so narron- that in practice it i l not possible t o light the ljurner-that is, the flame either fla.;hcs back or b l o w oft'. I n principle, it ~ o u l dappear pos%ble to ni~ititaiiiz 10
Vol. 40, No. 6
The latter fluctuations merit additional discussion. Cotioitlc,r that in an upright lighted burner the air entrainment nioni('titarily drops beloiv the normal average. Then the buo'~-anc~v increases, friction decreases, and if the mixture conipo3itioii is thereby shifted into the rich range-that is, past the maxiiiium (11 Figure 2-the flame pressure also decreases. During the interval of these conditions in the burner tube the static pressure, P,,~, remains belov normal; as a consequence, the air entrainment increases above normal until the burner tube is purged of the overrich mixture. The trend is non- reversed: The air excess decreases the buoyancy; it increases the friction [due t o the iricreased floiv, V (Equation s)]and also the flame pressure because the mixture composition is shifted back t o m r d the stoichillmetric. Hence p , increases above normal, and the cycle repeats itself. Such fluctuations are readily observable, particularly on long burners with appreciable purging periods. The flame colic i i i ~ ~ . clongate periodically and turn green as the mixture sliif'is to t l i ~ rich side and contract and turn blue as tlie tienil is i ( L-ndcr appropriate conditions the shift toiwrd stoicliiometiic. composition niay bring the flame monientady into the fla.li-liairk region; it then travels don.n the tube unril it is niet by (lie iticoming over-rich mixture and s w p t back to the tube rim. Sonietimes the incoming mixture is so over-rich that the flame is extinguished. I t niay be noted that flash tuljes-c>-liridrical burners operating in the flash-hack range-used for lighting a burner from a distant pilot flame, have vents or exparision c h a n bers to release the pressure, pm, and thus operate x i t h constant air entrailmelit. Fluctuations of the dcscribetl type arc not confinctl to upriglit burners but also occur in horizontal and even don-nriglit buriicis; the dependence of friction on mixture floiv alone suffices to 1)i'ocluce them. Iiomver, the)- arc less strongly developecl in the latter cases. BURNERS W T I I VEVTCRI DUCTS
\\-lien tlie flame is to be d i s t r i h u t d over a number of 11ot.t ry to tran4orm the x h o k strenni iiionicnc pressure. OtIic~i~\\-is~, I, the flames i v o u l ~ li ~ c the flame distribution unruly due t o turbule occur iii the port manifold; this ~ o u l dreduce the air ciitluitii i i v n t . The jet stream, therefore, enters a Venturi duct \ \ - l l ~ i~t u ~ v\-pnnda gradually before pa,sing through the ports. -4s < 1 1 ( t i \ I I
a
rn U
3 4 r 3
z
AX=At
2
0
20 40 0 20 40 60 NATURAL GAS FLOW, CUBIC CEkTiMETERS PER SECOND
Figure 8. Burner Operating within Flame Instability Calculated curves and experimental points
stable flame betneen gas flo~v-sof about 8 cc. per second to 14 cc. Honever, thelimits of flash back and blowoff shown here are accurate only for laminar flow free of fluctuations of velorit! 01 mixture composition. In the case shonn in Figure 8, the limits are actually drawn together by the residual turbulence of the jet and bp fluctuations of the mixture composition inherent in the entrainment process. pel second.
Figure 9. Scheme of Pressure Changes i n Yenturi Duct
iii Figure 9, plane m noli- lie3 in the burner liend lieliind the ports ant1 plane x lies in or near the throat,, depending on \rhetlier or not area A, is equal t o the throat area, .I,. The size of -1, is evidently limited by the f l o ~of entrainccl air that can be puslied through tlic burner, and if the total port area, .A, is suificiently small, A , becomes smaller than .II. I n this case the stream expands from -1, to .dt with eddy losses in the manner described in the previous section, and the Venturi duct is effective only during the cipaniioii fIo111 .4t t o , ! 9 n , The initial cx-
INDUSTRIAL AND ENGINEERING CHEMISTRY
June 1948
psrision from A, to A , increases tlie static pressure iii the throat above atmospheric. -1s total port area, .A. i! increased, a point is rcacliccl where -1, = A i t ,and the stnti tlie throat becomes atmosplieric. Further in -4, > .I', ivliich need n o t entail an 2pp1 if tlie duct eiitr:mce f o r m a graduall>- co1 this case the otreani coiitt:acts from A i zt o -1: irith iiicrease of vclocity and corresponding decrease (if z t n t i c pressure in the throat heloiv atmospheric (16, 1 9 ) . If the assumption. of Bernoulli's tlieoretii-frictionlcjs Aoiv and iiniforni velocitJ- o w r the stream cro.ss sectioii--n-ere valid in the T-enturi duct and the ports, one could w i t e for tlie case .lZ>-4(, and for negligible hack pressure oi the flame (p- flux, q, in the t l i i o n t ant1 t h e head of n test l i t ~ i ~ ~ i e r .
;
pli'
t
p?i?
0
Figure 10. Static Pressures, p , a t Throat for \ arioiic Port ireas
I = Io
=
04
PORT AREA
((1
'I)
-
+p
I)
6
In the calculation of
= il?cl?,'
L
= il;rt?/E ((32rt1,, the errors canrcl out
JI"
u22t(!r, arid
to somi: cytctit.
Hoivever, in Equation 11 the more nrcuratC values of ti iili~tiiiied froin the g:is-anily~icnlvalues of 1' liiivc h w n used. The iliita are sunitnariaid in Table I. .Utiiougli I I O gI.c:at n c i ~ r a c > can . be claiinetl, the energy flus i n the h u r ~ i e rl i i w l is c.11iisistc~iit1y found t o be sninllcr than in tlie iliroat 1 ) ~ an - :iiniiunt. louglily correspoiiiling to tht, contributioii of the velocity p ~ ) i i l e . It appears that this part of t h e eiie~,gyflux i, lost ant1 t1i:lt t h e
(11)
-.
1lie first term is contiiliuted h>- the kinetic energy corre5Ii~)iidingto tile average velocity, V; = T*,/*lu, the second term by r l w velocity profile, arid the third term liy the potential energy; p i. i h e differwire h c u \ v w n t i ~ .ztntic c and t h e atmosplie~~ic pre,ssure.
Thc 1-enturi duct tis cut into a lilocl; of iiiaple ivood according Tlie throat dianito tliiiicniioiis suggc;tctl by anothcr n.0~1; ;:I, eier n-ns 5 / . inch. The inlet profile h:td a curvuture of 3-inch radins. Tlie duet espanderl a t an angle of 2' to a diaiiicter of 13/15 inch. Then follo~~-ed a reiiiov:ible perforated st tion.;: consisted of I,'\-in sampling tube iras attach n1nde :it thc head nr1d T W ' ~ ; cnre n - n s taken to ayiriil ail)- ridge3 protruding into the atrl>:31n. Thc gngcj were of tile -lope t y t and filled TI-it11water to \r-hich :t wetting agent e11a&jc(l. Readings n-ere made by 1llc':iIls oi n telc5copc. coult1 &o lie l l l e a u r e d bv means of si .ileiitler tube i\-hic lirrocjucetl tlirougli the port to any ( i c ~ i i ~ cpoint ~ t l n-ithin tl , A ~ f ; cclosing r the end and cutting -i(lcx Iiolw it1 the tube, it served. nlternat as a Pitot tulle and a .static tuba. The accuracy oi the pre readings \vas about) -0.05 111111. of water. Tile g;i? orifice \\ giietl {vith the axis of
Tahle I.
Decrease of Energ? Flux along n \ e n t i i r i l h c t cui
> I
1
0 64 0.25
1.0 0 01
0 00 0.24
0.14
0.2i
0.39
0.00 0 "I) 0.21
0.5.7
1.0
0.21
0.01
0.18 0.00 0 40
(1.00
0 13
0 18
0 15
0.14
1128
INDUSTRIAL AND ENGINEERING CHEMISTRY
stream in tlitb duct behaves as if the velocity in the throat plant, \\.ere uniforni. It follo\rs t h a t at zero throat pressure, ratiil A t / A (throat area to port area) must equal the port dischargca coefficient. This c,oefficient is defined by the equation, p , = 21 pT'?/a'A?; 01? is equal t>o E if the only loss occurring in t l i t ' efflux process is a change of the velocity profile b y contraction ani1 frict ional retardation a t the stream boundary. From the foregoirig, liolvever, p,,
=
21
p~
z/'t;
as the 1;inctic cnri'gy ill
tIith
hurner head is very sinall; iietice, AJLt = a . \.slues o f (lischar.g~coefficients are usuall>- found t o be betivc.cn 0.6 U I ~ I 0.7 which appears sufficiently consistent with the oJ)srrvc'iI r dt1.4 -0.7 at zpro thront pressure.
Vol. 40, No. 6
valid rvlatiuns gnverning the entraiiimetit process. It is coliceivable t h t problems of this kind may ultimately he solvid b y tlieory, but in the absence of a theoretical treatment satisfactory nnhivers may pos,jibly he found by further psperiments. SU;\I\I.ARE
. i n experiment a1 antl tlieiiretical stuilj- has hecn ri~iitlei r t I lie air entrainment in gas burners coiisistiiig of a f r w j(,t of fuel gas in air and either a cylindrical burner tube or a Venturi duct which leatls t o a manifold of small Hame ports. For cyliutlrical burner tubcs a i equation oi the air entrainment has b(y:ii derived o n the that part of the stream nionientum is traii.;fornicd into static ure corresponding to the flox resistanre inipwivl I)>- I riction, buoyancy, and the back thrust of the flame. T h c air i,nti,airinlent c3alculntedf r o m this equation as a function of burilc,r dini?ii+ i r i s , burner positioii, anti gas flon- agrees \vel1 with t l i c b c,.;p\i'imentul tlnta. Fluctuations of the air entrainment in cyliritlrii.al burners [ire found t o be inlierent in the cntrainmcnt pro Hurners ir-it11 Venturi ducts are required ~ d i e nthe flanies is to he (listi,ib -cr a number of port olwnings brcause in this ii is i i i . to traniform the stream inomrntuni as c c i r i i p l e ~ i ~ l ~ ~ as possible into static pressure. I n so far as the assuiuptions of 13ernoulli's theorem are valid for tlie f l o in ~ t,he Venturi duct, an equation of the air entrainment can be readily derived. AS a mitriliution to the study of the lionideal conditions n.liic.11 c z i ~ w the actual entrainment t o be lon-c,r than predivtcd, an e y w i niental energy balance of the flow lias been made tjctwlen the, throat and the head of, a test huriicr. For this purpose thr. potential energy, the kinetic energy corresponding t o average: velocity, antl the kinetic onergy contributed liy the Tolocity profile have been separatply measured. From tlie data it \vas coiicluilcd that tlit latter contrihution i c limt hetn.ecn throat and ;ieatl in tho iorrii of c,tlllv tiiotions. cui18
B $
9
5
*3 6 x
N N
NO\I E h C L -YrCR :E
i 400
200
0
w
r
=
d i ~ t a n i ~from c axis of burner tube,
C'IL
u = velocity in it ('rob ectional elelniltit d.1, cm. ional area of the gas stream, square c m .
K
DISTANCE I FROM THROAT AXIS
INCH
CM
DISTANCE r FROM THROAT AXIS
Figure 11. Pitot Tube Jleasurements ant1 Derived Functions across Throat of Ventriri
Burner Throat 6 / 1 8 inch = 0.794 cm; orifice area = 5.26 X 10-8 sq. om.; throat-to-port ratio = 0.675; g a ~ flow = 26.5 cc./eec.i V/Ve = 14.9 p = 1.1 X 10-3 g . 1 0 ~
The loss of the energy atoreci in iionutiiforni vcloclt> dlstllbution becomes understandable if one considers that the E t ictiirr~ at the jet boundary which supports the velocity profile dc~cleasc. rapidly as the stream enters the expanding duct. The T elocit \ profile thus becomes unstable and breaks up into eddies l n u e l i ~ t i the manner of a stream entering a suddcnlv enlarged duct The problem remains of establishing the eneigy b a l a i i e betneen the plane 2 and t h e throat in the iange of laigc ricgativi and positive throat preswres. and thus t o arrive at pc,uriall\
kinetir energy crossing it plane per unit time. c'rgs per acrond I = nionientuni crosbing :I p1:tniI prr unit time, grani r n i . 'per square swund I, = length of burnc,r tuho, m i . T' = rate of flon- of g treani. cr. per necoiill u = pnrt diuchargc: coefficient = kinrtic energy coefficient, dcpendt'iit on the degrcte of uniformity of the distribution of velocity over thc strcani cross section = nioment8um coeficicnt, dependent on the degree of uniformity of the ilistriliution of velocity ovrr t h r strram crow .wction 9 = viscosity, poise p = density, grains per w , Su = hurning \-i,loc.ity. cni. per second =
Subscript 5 h = burned gas t)? = plane of maximum static pressure a-iti~iritrurrier tube none = planr of burner ports o = planc of fuel gas orifice t = plano of throat, of T-enturi durt G = plane n-here entrainment of air w a w I/ = any plane of burner tube
e
INDUSTRIAL AND ENGINEERING CHEMISTRY
June 1948 =
01
refer5 to effect of friction at t h e tube XTalls
,8 = refers to effect of the thrust of the burned gaq y = refers t o effect of the buoyancy of the gah stream LITERATURE CITED
(1;
"Combustion," 3rd e d . . p. 110. T.;astun, h\lnr-k Printine Co.. 1932. (2) I b i d . , p. l i 7 . (3) - h i . G a s . L o r . Testing Lab. Bull. 10 (3Inwli 1940). (4) I h i d . , 17 (August 1943). (5) Ihid.,26 (May 1944). (6) Ihid.,37 (September 1045). ( 7 1 Berri-. JY. > I . , Brumhaugli, I. Y,, Moultoii. G .I:., a n d Siiawn. G . E . , .\-nfZ. Bur. Standards, Tech. PiLpcr 193 (September 1921). ( 8 ; F:wald. P. P., PSsclil, Th., atid Prandtl, L., "Plij-sic,>of Solids mid Fluids." 2nd cd., p. 251, London, Blacliie and Son, I9:W. (9) I h x . , p . 226. .hi.
Gas Ssaoc.. I~
1129
(10) I t i d . , p. 277. i, l l .) Komalke. 0. L.. nnd C'eaelske. X , 1 1 . . ..lni. Gua .4880c. /'roc.. 662-86 (1929). (12) Landolt-Bornstein, "Physikalisch-rhemische Tabellen," Pup. Yol. 1, p. 143; S u p . V&. 2, p. 137, Berlin, J. Springer. (13, Lewis, B., and von ],:]be, G., "Conihustioti, Flames a ~ l dExp10iioiii of Ga.;eh," 13. 203, C*aiiihridpe. (":itiibri(lgc T-iiivcrSity Press, 1988. I
.
(14)I h i d . , p. 342. (151 Lewis, B . , and von Elhe, (;,, J . Chem. Ph,gs., 11, i.5 (lCI1:3',
Properties and Uses of Alkanesulfonic Acids 1lie alliane~iilfotiicacitls ((:,'II:*~ - ,SO,II) ~ i u \ -beeti e Imowri for m a t i > > e a r s ; tbeir prrparation arid some of t h e properties of various nierrilmrs o f the series have been clescrilJd in t h e literature from time to time. . i n excellent re\iew o f prel-ioits work on the clieinistr>-of these acids is g i v e n I): Suter (8). -ilthoirgh a few of t h e alkanesulfonic acids of highrr nioleciilar weight ha\-e heen produced for s o m e t i t n r o n a coritniercial scale for t i w a e surface active
agents, allcauesulfonic acids of lower molecular weight have remained laboratory curiosities. Recetitl) this laboratory developed a catalytic process for large scale production of either individual or mixed alkanesulfonic acid*. This paper describes t h e preparation of the C to C, acids, summarizes published inforniation on their pli? sical and chemical properties, records new information conrernirip these properties. and siiggestb potential uses.
TH"
until the transform:ttion to sulfoiiic~:~i*ids is vir.tu:illy c o t u 1 j I ~ , t ~ ~ . Few side reactioii.r occur, a d yiclds of tc~hnic.:al sult'otiic acitls approaching the theoretical are obtsiiiccl. The process was applicd to the preparat,ion i l f nict1iaiic:- :tiid etlianesulfiinic acid$, b u t the chief eidphueis was 011 synthesizing a niixtui.c~of acids. Crude alkyl disulfidcs, averaging approximately two carbon atoms per alkyl group, and consisting chiefii. of symmetric:il mid unsymmetrical methyl, ethyl, and propyl disulfid(,s i n all possiblc combinations, viet'c oviclized to yii,lrl :L mixture of niet hane-, et harie-. propaw-. and prolmhl>- wm(' hnt R nesulfonic acids.
, 7
catalytic riictliod dewloped for the synthesis of these acids is relatively >iiiiple. By use of this process primary and -icinil:iry niercnptans, or the corre.3ponding :~Ikyldisulfides, have I , t x t i osiclizcd to all~anr~ulfonic acids of 90 t o loo('; strength. Tlii, i ~r-i.i.-:ill tjiluatioii* are :
sm1-r + 3 0 , +2~s0,1i 21j-S-S-R -+ 502 + 2EI2O +4IISOSH
m y SIC 4 L A N D CII E ~ I I C A L PHOPERTIES iti
t h c i liic
ixtiii~c~,
alkj-1 disulfides are eruploj-ed as the starting iiiaterials cnre is talien t o csclude water from the svstcm. alkanesulfonic ~ihvtlridescan lie obtsined. \\.lic,ii
Thc loiver all~tnesulfonicacids arc strong, nonoxidizing m%k. \\.it11 the ewcption of incthaucsrilfonic :tcid n-hich mc>lts at
~ i i d
:I
Laboratory oxidation of dinietlij.1 arid diethyl disulfides has ?-ielded products containing u p to 8OrC of the corresponding suli i Itiic aiih>-dride.s. The osidarion of alkyl disulfides t o alkaiiesulfotiic acids is now being csrried out successfully on a pilot plant xcnle, and it.. ti,ari;latiori to coniniercial scalt' is c>spwted in the 11c~arfuture. In the operation a mixture of thv aIl.lt l i d f i d e s a ~ i dthe :ippropii:tte aniciuiit C J ~Tv:itilr are o s i d i z i d i n tile pi
c 0 1'11 1 ( i l l I l l 1
B.P.
;c. ~~~
. 11111.
iJ.r', c'.
SI,.I ; I . . 2io/4O0
C'.
1.0 1 2 0 (1 1.4844 i n 17 0 1 3341 1 0 +7 i I 2516 1 0 -~1,5 2 I ii106 CHaCHrCH:CHrS03H 147 0 3 a Boiling points o b t a i n e d in thl, l a b o r a t o r y . T h e value for C'I13CH!SOsH)C,Hz (synthesized i n this l a b o r a t o r y ) is a p p r o u i i n a t e , i i n c e soinc decompo-ition occrlrred a t t h a t teriiperatlire a.nrl r ~ r e * ~ i r e .
CHsS03H CI13CHzSOIH
122" 123" 13R 123"
~ ~ $ : ~ ~ ~ o " , 2 ~ ~ ~ ~ I b
