The infrared spectra of spiropentane, methylenecyclobutane, and 2-methyl-1-butene were measured in the region from 3 to 14 microns with a rock salt prism spectrometer of medium dispersion. The pure samples were prepared at the NACA Cleveland Laboratory. The vapors of these three C5 hydrocarbons were investigated at room temperature and at pressures in the range from 80 to 300 millimeters of mercury absolute in a 10-centimeter cell. The spectra were compared with each other and with Ramon spectra for the same compounds

Cleaves, Alden P

Sherrick, Mildred E

English

NASA Technical Reports Server

NATIONAL ADVISORY COMMITTEE 
FOR AERONAUTICS 
TECHNICAL NOTE 
No. 1160 
THE INFRARED SPECTRA OF SPIROPENTANE 
METHYLENECYCLOBUTANE AND 
2-MIZTHYL-l-BUTENE 
By Alden P. Cleaves and Mildred E. Sherrick 
AircraSt Engine Research Laboratory 
Cleveland, Ohio 
Washington 
October 1946 
hnqley FieW VII. 
https://ntrs.nasa.gov/search.jsp?R=19930081858 2020-06-17T22:48:14+00:00Z
NATIONLL ADVISORY COMMDTEE FOR AERONACTICS 
TZHNICAL NOTE NO. 1160 
TZE IIURARDSPECTIWOP SP~OPM'TAii,MlDHYANE 
AlID Z-MZZCIHYL-l-BUTEXIZ 
By Alden P. Cleaves end Mildred E. Sherrick 
The infrared spectrs of apiropentans, methylenecyclobutane, and 
.2-methyl-l-butene were measured in the region from 3 to 14 microns 
wfth a rock-8&t prism spectrometer of medium dispersion. The pure 
eamplee were prepared at the KACA Cleveland laboratory. The vapors 
of these three C5 hydrocarbon8 were inveatlgated at room temperature 
and at pressures in the rage from 80 to 360 millimeters of mercury 
absolute in a lo-centimeter cell. !Zhe spectra were compared with 
each other and with Rm data for t&e same compounds. 
LNTROIXJCTION 
. 
Spiropantane was prepwed at the NACA Cleveland laboratory by 
the debromination of pentaerythritylbromide with zinc as described 
in reference 1. Three hydrocarbon products of this reaction have 
been studied elsewhere by electron diffraction and identffied as 
sp:ropentane, methylenecyclobutane, and 2-methyl-l-butene. (See 
references 2, 3, 4, and 5.) Raman frequencies for these three C5 
hydrocarbons, compiled from the results of several investigators, 
are listed in reference 2 but their infrared spectra are not avail- 
able. Apparently the molecule structurally most similar to epiro- 
pentane that has been investigated in the infrared is cyclopropene. 
(See reference 6.) The vibrational levels of' cyclopropane based on 
Reman end infrared data have been reported in reference 7. 
Infrared spectra furnish basic data essential for spectrophoto- 
metric analysis and for the detarmination of molecular vibrational 
levels. This report presents the infrared spectra of ssmples of 
epiropezltane, methylenecyclobutane, and 2-methyl-1-butene, isolated 
and purified at the NACA Cleveland laboratory. These spectra of the 
hydrocarbon vapors were measured at room ttznperature in the rock-salt 
region from 3 to 14 microns. 
2 NACA TH No. 1160 
Infrared spectrometers. - Two spectrometers were used in this 
invest;?gation. One of these a?ectrcmeters was adapted to record 
transzn~ttcd infrared radiation as a function of wavelength. This 
infrared spectrometer, described in detail in reference R, has a 
6Oo r:2ck-salt prim with faces 6 by 7.5 centimeters, a Globar aourcc, 
and a thom;.opile Peceiver. A high sensitivity galvanometer c~nnectod 
to the thermoyile as shown in figure 1 deflects only slightly. A beam 
pi" light reflected from the galvanamter mirror so illuminates twin 
photocells in an aplifier circuit adapted from reference 3 that a 
Leeds-IJorthru3 pen-recording E$eodomax traces the amplified thermopile 
output. This infrared spectrometer was used for rapid qGalltative 
exploration of the spectra. 
The second infrared spectraeter, which is described ii: refer- 
ence lO!hae a smaller 60' rock-salt prism (faces, 4 3y 6 cm>, a Ncrnat 
c;lower source, and a thermopile receiver. A micrmter scra7 attached 
:o the in&rument permitted manual adjustment of wave len&%l. Ratios 
of deflections of a high-sensitivity galvanometer when the irjlrared 
beam travoraed a lo-centimeter cell, empty and filled with hy-lrocarbon 
vapor, reepoctively, are the percentwe t:ansmissions plotted in the 
spectra. 
E;&rocarbons. - The purity of the hydrocarbons prepared and iso- 
lated by the Fuels Synthesis Section of t:ie NACA Clevelcand laboratory 
V&B estkmted on the basis of freezing-point data to be high, 7robabl.y 
&mre than S8 percent, The &ysfcal prop3rties of the three hydrocarbon 
smgi.es are reportsii in reference 1 as follnrs: 
--- 
Compound 
[Freezlw'Boiling 'Jkdex of 
1 I 
Density at 
point point at refraction 2Oo C 
("cl 76C m 
I co@ 
nzo hT=/d 
D 
S2iropontane 
I 
-107.05 39.03 1.41220 0.7551 
Motllylenocyclobi~tane -134.68 
f 
42.22 / 1.42087 .74X 
2-Meth.vl-l-b~ltene -137.50 31.12 1 1.37781 .6534 
REULTS 
. 
. 
The infrared spectra tn the region from 3 to 14 microns for 
s:)iro2entane, methylenecyclobutane, and Z-methyl-l-butene aro pre- 
sented in figcrea Z(a), 2(b), and 2(c), respectively. Ap:roximata 
effective slit w'_dtlls are indicated. The contours of peaks of the 
UACA TX No. 1160 3 
LCEI~ Intenca bands era ?lotted for two prassuras of the hydrocarbons 
$5 the call to verify the position and shape of each peak. Tlze 
X3-mlllimetar pressure used for spiropantane was lower than ait'a3r 
of the prasscras uead when determining the corngate spectra for the 
o-tLar tV0 compozn&3; bance, each mkimum where transmission 1s lass 
than 90 Tarcant probably represents an absorption band and soma vary 
weak bands may net apgaer. A surva3 with the recording spectrometer, 
hOJT3E?~, &m~ad no nalT bands when the Iressura of SpiroTentana FELS 
about 300 miilinatars of mercury absolute. 
T3a :,osLtions of all brat the we&a& band8 are listed in table I 
In units of mtcrons and fnvarea centimeters. 
POSitlOES varied from a3octf5 cm-l at 
The uncertainty of the 
for fraa_u3ncias above 2OOC cztwi. 
lower frequencies to f10 cm-1 
Raman freg.anciaa from rafarenca 2 
are included fcr the sake of ColXparison and completeness. Stillari- 
ties of the qectra ara aspaciaily evident but the differences, which 
ar3 an asaantlal basis for fnfrerad analysis of binary or ternary 
alxturas by the method of rafarance 10, may also be discerned and 
lntaqratad, A strong band at approx'%ataly lc) microns (where, 
aocording to reference 6, cyclopropana also absorbs) cha,rectarisas 
3~i3?OpWlt3XlC3j whereas strong ebaorption amaars st a;?>roxim&.aly 
6 microns only in the spectra of the other ~TO compounds, each of 
which col?tains a doubla bond. The rather intense band at 7.24 mTcrons 
in the spactrlz of 2-methyl-l-butane has no countai'part Fn the spectrum 
of spiropantane nor does mathylenecyclobutane havs a resolvable bend 
at tlnis wave iang+h. In the three spectra smell ralatFva shifts in 
the rJositlons of other bends are atidant. !&a outstsnding ti"ailari- 
tie3 are the strong bsr?ds et about 3.4 and 11.4 micro&ns that a?>ear 
in all thzae spectra. 
In general, a molecule 3ontstiing n aima has (3n-6) normal 
modes of vibration; acccrdkgly 53 such fur&mental's would be >ra- 
dictsd for t,jLe tire C5H6 isomers s.nd 2-mat%yl-l-3utane should have 39. 
Some of these vibrations will be infrared-aztiva, others ~111 be 
&Reman-active, en?. some will1 2ro3ably be active in both Ramsn and 
infrared spectra. S-try 'Ln a molacula is associated with cokci- 
dance or degeneracy of soma fondemantal frequencies, hence, probably 
fewer than 33 different bends WOUxk be detected in infrared e& 
Retman qactra for each molecule. ‘I!lce ii~ts of ep>roxlZmataly 20 dif- 
fc?ent frequaxlcs (not nacassar:ly all fundamentals) for each mol- 
acnla in tebla I ';robably include nearly al.1 resolvable ncrmel vibra- 
tions, and possibly a few overtones and combinations. Some intense 
bends may represent two or more ovarla~ping fundazentals. 
4 NACA TN No. 1160 
In the spectra of mathylanacyclobtdana and 2-methyl-1-butene, 
the bands at about 6 microns m&y be associated with vibrations of 
tha C=C bond. The l@-micron absorp%1on by spiropantana is chsractar- 
istic of a vibration in the cycl;c carbon skeleton of this molecule. 
Cyclopropana alao shows absorption in this region, although it does 
not hava a band at exactly 10 microns. (See reference 6.) Absorption 
of madium fntansfty at about 8.6 microns occurs in the spectra of both 
compounds that have closed rings but it is absent in the spectrum of 
2-methyl-l-butane. Absorption at approximately 3.4 microns in all 
three spactra is characteristic of C-H type vzbrations. The bands in 
tha vicinity of 880, 1170, 143C, 1670, and 296C cm-l are both infrared- 
and Ram&n-active in the mJlacules of which they are charasteristic. 
Aircraft Engfna Raaaarsh Laborstory, 
National Advisory Committee for Aeronautics, 
Cleveland, Ohio, June 25, 1946. 
1. Slabay, Vernon A.: The Synthesis of Mathylanacyclobutena, Spiro- 
pantane, -and 2-Methyl-l-butane from Pantaarythrityl Tatrabromide. 
NACA TN No. 1023, 1946. 
2. M.zray, M. J., and Stevenson, Eugene E.: The Debromfnation of 
Pentaarythrityl Bromide by Zinc. Isolation of Spiropantana. 
Jour. Pm. Cham. Sot., vol. 66, no. 5, May 1944, pp. 812-816. 
3. Donohua, Jerry, Humphrey, George L., end Schomakar, Varnar: The 
Structure of Spiropantane. Jour. Am. Cham. Sot., vol. 67, no. 2, 
Feb. 1945, pp. 332-335. 
4. Bauar, S. H., and Beach, J. Y,: The Structures of Mathylanesyclo- 
butane and Hexamathylathsna. Jour. Am. Cham. Sot., vol. 64, 
no. 5, May 1942, pp. 1142-1147. 
5. Shand, W., Schomakar, Varner, and Fischer, J. Rodney: Tha Struc- 
tures of Mathyianacyclobutana and of l-Mathylcyclobutane. Jour. 
Am. Cham. Sot., vol. 66, no. 4, April 1944, pp. 636-640. 
6. Bonnar, L. G.: The Infrared Absorption Spectra of Cyclopropsna 
and Ethylene Oxide. Jour. Cham. Phys., vol. 5, no. 9, Sept. 1937, 
pp. 704-706. 
NACA TN No. 1160 5 
7. King, Gilbert W., and Armstrong, Robert T.: The Vibrational 
Levels of Cyclopropane. Jour. Am. Chem. Sot., vol. 58, no. 9, 
Sept. 1936, pp. X80-1584. 
8. Barnes, R. Bowling, McDonald, Robert S., Williems, Van Zandt, 
and Kinnaird, Richard F.: Small Priem Infra-Red Spectrometry. 
Jour. Appl. Phys., vol. 16, no. 2, Feb. 1945, pp. 77-86. 
9. XcAlister, E. D., Matheson, G. L., and Sweeney, W. J.: A Large 
Recording Spectrograph for the Infra-Red to 1%. Rev. Sci. 
Instr., vol. 12, no. 6, June 1941, pp. 314-319. 
10. Cleaves, Alden P., and Sherrick, Mildred E.: Infrared- 
Spectrophotometric Analysis of Binary and Ternary Mixtures 
of Liquid Hydrocarbons. MACA ARR MO. E5F27, 1945. 
. 
NACA TN No. 1160 
VAT% Ll3JGPHS AND 'WAKE MUMBERS OF BAIDS IN lDFRK%D SPECTRA -AJJD 
WAVE I~ZJMEERS OF SlilJ?I'S IN R&MI? SPECTRA OF SPlROEi~Aii 
f:~ZWEIYIZIJECYCLC, AND 2-MXTBXL-l-BUTEIJE 
[Raman data taken from reference L.] 
i a, 
3.4G 2940 I 
I 2991 
13065 
6.S8 
5.95 
5.70 
4.75 
4.31 
3.33 
2320 
2a26 
2861 
2902 
2921 
2960 2952 
2886 
3072 
3.37 
2340 
2856 
2893 
2317 
2942 
2970 2971 
2964 
FTam-mxbsr values above 2OGO haTe only three significant 
f iguros. 
Iilr"ra 
microns 
Spiropentane 
red 
1 
pT&Lma~ 
I 
v 
I 613 
12.60 
71.46 
10.05 
9.49 
8.62 
7.46 
6.96 
5.68 
5.30 
4.E7 
4.40 
4.23 
I 7e1 77s 
273 872 I 995. I 
1054 1033 
1160 1150 
1337 1397 
1437,1426 
t 
17611 
15871 
L20501 
2270 
2330 
! 2836 2S9i 
4ethylenecyclobutane) 2-Methyl-1-butene I ~~ 
Lrs-rc: 
nicrons 
13.20 
11.38 
9.82 
9.32 
0.55 
8.00 
657 
758 
879 873 
1018 SO7 
s 5 7 
1073 
1170 1191 
1250 
1391 
12.75 
11.25 
9.95 
9.30 
252 
393 
433 
465 
530 
70s 
784 773 
889 EGO 
lG05 964 
1020 
1075 1091 
8.09 
7.24 
1433 1428 6.87 
1620 1679 6.05 
1755 5.60 
1236 
1381 1390 
1413 
1456 1433 
1653 1654 
1786 
"2x0 4.90 32040 
4.27 
Xational AdTrlsory Committee 
for Aeronautics 

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RAT IONAL AOV ISORY 
COUllTTEE FOR AEROMAUT KS 
onus 
A Trln photocells RCA 925 RI I 0, DO0 E Zero shiftar R3 
B Input for callbratlon emf RZ I.000 6 High-sens It lvlty galVanOmetar R4 
C Condanscr 0.05 q fd 
D Anpl If ler tube 6666 
R7 .75 T.P. High-ssnaltlvlty thsrmopils A5 
S Speodamax recorder 5 
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Figure I. - Circuit diagram of twin photocel I amplifier for recording output of thermo- 
Pi le in infrared spectrometer. 
Ial sp1mpentmr. 
,,gure 2. - Ir&nrn.3 0paDtl-a of rapDrl In 104sntlnetcr call. 
IWTIOMAL AWlSollY 
C[WIITTEE FOR AERUtAUTlCS 
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2 3 8 . 5 6 7 9 la ll 12 13 15 15 
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rmre length, mlcrrms 
coj &Mst&Tl-1-but*e. 
,lgrre 2. - aonclud6d. lnrnrod speocra or vapors in 1o-centLMtcP cell. 
NATlomL ADVISORY 
COUIlTEE FaR AERONAUTICS 
- c 
. . . 
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The infrared spectra of spiropentane methylenecyclobutane and 2-methyl-1-butene

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