-
-
1827
NWlB.8
mm.). Yicid WUI 171 r., 96%. Broaon' nportr a boilthat even boiling formic acid (K." 1.77 X lo-'; point d 111-112' (10 mm.): m% 1.Isg); a% K.* 1.55 x lO-')';ddSdirectly to I to produce ing 1.5010; d i e 1.113; M R D 48228. dicyclopentcnyl formate (IIa or b) in nearly A d . U c d . farCIIH1401: C, 7'2.4; fl, 7.9. Found: quantitative! yield, w b m s B m n states in his C,74.3; H, 7.7. example t&t the addition of formic acid is T h e f a m a t e WIU saponifmi by refiuxing with 1.5 cquivachieved in about 71y0 yield by catalysis with dents of ethandic: potassium h e o x i d e fa e h t h. 40"ro sulfuric acid. That our reaction likewise in- T h e sdvent waa then distilled OB, the residue taken u p benzene and +a~hcdwith water, w l o p c n t m d v o b an "endolxo-rearnngemet," was shown with (111) distilled at 83-86" (2 mm.), aS a dar, d a b s by saponification of I1 to dicyclopentenol (IIIa or li uid d bigti \risosity. It ertrts a s t m a & ursthtic b), identical with the product obtained by d b t e;fect on the human tongue' a".% 1.6#)6. Brosoa' reports n% 1.w.me denp~ureth~n of I I I melts hydration of I in the presene of sulfuric acid.' t 163' (Bnuon. l64-lSrr0~ and s h a no dcpasiori The reaction described here provides a most aupon admixture of the phenylurethan, prqm-4 from convenient route for the preparation of dicyclo- dicyclopentcnd arrording to literature.' Dih~dro++oprot~fi F m e . - T k f m t e (11) peutenol and its higher homologs. We have found, e. g., that tricyclopentadiene (IV) by the was mixed rnth an e q u a l vdumc of W% alcohol and hydroover R a c y nickel at rooui temperature ilnd same method gives a qunntitative yield of tricy- genated atmospheric pressure. The required amount of hydrogen clopmtenyl formate (Va or b). I n addition, we was absorbed during two h w n . Distillation gave a 02s; have been able to develop the uncdtalyned addi- yidd of a cdaln* dil, b. p. 137' (35 mm.), #'ID 1.4870. tion of formic acid into o. method for the quantiA d . CPlcd. for CIiH&: C,73.3; H,8.Q. Fmd: C, 73.1; H,9.0. tative determination of dicyclopcntadiene.' Tt-icydopenrcnp.1 formate ( V ) was prepared in the same before, by eight hours of reflux. I t boil.; ;it 1:No (0.2 mm.) and forms a cdorleo, virouri liquid: ntlfi 13352; dIe 1.162 MXD 66.40; yield was quaiit i b t ive . A d . C r r l ~ r for . CzJirU,: C, 78.7; €1, 8.2. Pound: C,i X . 6 ; I i , X.: . Spoonificatioii of I.as , d m i b e d above, gave a 957; yield d tricyrlopcntmd in an c x n l k n t state ol purity, 11. 11. lMo (0.4 mm.). The sutrJrtpan formed a hard, brittle glass, which after statidiiig for three monthr crista!lircd spontaiirously and then showed an m. p. of 115 , as cltrribnl hy Bruson and Hiener.' No indication of t h r prcscricc of ;in i w m a wtu found. way, as described
0
t
I
I)ASIEL SIKPPKnserum I ? ~ S ~ ~ T C T B ~ X l l O V O T l l . I'ALBSTISK
HKCBLYHD FBBRCARY 8 ,
1w7
.
IIIh
IIIa
A Parabolic &Won between Bond-Ordet m d Interatomic Distance BY J. L. KAVASAV
The author' has advanced an empirical relation betwten bond-order, N,and interatomic distance, D (in A.)
where nl arid nt are the prtricipal quaxiturn tiumbers of the valence electroris in the bonded atoms and a arid b are constants for the specific atom pair. m a i n ' has recently proposcd a generalized m cation of ( 1 ) to
1)
\'a 0
3
Vb
where Z is the s u m of the atomic numbers of the bonded atoms and K I and K , are constant for all atom pain having the same values for nl and Lagcmanri has shown an average per cent. deviation of only 1.:3yb between e x p w h e n t a l interatomic distance values anti those given by q u a tiori ( 1 ) for a nurriln~of first row linkages.
*.
11)
(2;
J I. Y.vmamu. J L k m I ' h y s . l a , 467 1 1 0 4 4 ) R T In#erman. i h d 14, 743 (1948)
Nom
1828
Vol. 69
The author' recently showed that for carbon- 1.53, respectively. Equation (6) leads to the carbon ban& the points of plot of E, the bond- values 1.670 and 1.522, whi& (1) yields the values energy in kcal., against the bondorder N lie on 1.668 a d 1.50s (D1.39 A., Docrp~u = 1.42 A,).] ~ h e s evalues agree clo~elywith the parabola those derived by C o b and evidently N of (1) (1 - N/4)' 1 - E/133 (3) and (6) may be interpreted 88 the bond-order as The fact that the number four appears as a con- defined by Coulson's molecular orbital treatment. stant associated with N may be of si@icance Using the valencebond rcswanc(t method, since t h i s is the theoretical maximum bondorder Penney' has calculated the values 1.623 and 1.45 for carbon-carbon bonds as well as being the
-
-
number of carbon valence electrons. By eliminating N from (1) and (3) we obtain the equation D =a
+b
(1
- N/4)'
-
(3)' (4)
where y = 4 - 4 dl - E/133, relating E and D for carbon-carbon bonds. The numerical values' of a, b and n are 1.015, 0.875 and 2, respectively. Inspection of the points of plot of E against D for C - C , C=C, and c-=C bonds (58.6,100,123 kca). and 1.54, 1.33, and 1.204 A,, rtqectively)'J shows that the relation is very nearly linear. Cherton' has given a simple linear expression relating these variables. If we assume that this relationship is actually linear, then by setting E = P ( f - D) (5) in (3) we derive a relation between N and D for carbon-carbon bonds of quite a Merent type from (1) which relates these Same variables. USing the known values of D for C - C , C=C and c--C bonds we find from (3) and (5) that' and
for tlpese same quantities. Taking the energy of the benzene bond to be l/, (&(Benzene)) 6Ec-a') = 85.9 k d . in (3) yielde N-e = 1.62. However, since the interatomic distance appear to be more accurately detennined than bondis indirectly determined energies, and E-. above, the former correspondence seems more significant.
= 1.488(D
- 1.162)
E = 197.9(1.834 - D)
Since thh note W'LU prepared for publication a paper by bauing upon this topic hse sppeprrd. By considerations of the form of equations (1) and (2) and a model f a multiple carbon-cnrbon bonds Bernstein has
Ban-'
been led to two essentially simplified equations of similar form which fit the known data remarkably well. (8) (8)
W.C. Penney, ibid.. l U A , 308 (1937). H. J. Bernstcin, J . C h m . Phyr., 16,
284 (1947).
Tbne
equations arb
for all wmmetrical linkaaes. and
-
-
(6)
fw rymmcttid linkngea of tHe 6rat r o w a t o m (2 ammic number, Lh single bond distanrr). By using the additivity rule the bond distance for unsymmetrical links m a y be calculotd
(7)
Lo9 ANCELES24, CALIFORNIARECBIVED MARCH3, 1947
UNMBXSITY OF CALIFORNIA
The curves represented by (1) (for carboncarbon bonds) and (6) correspoad very closely in
the range under consideration and for N = 1, 2, 3 the correspondence is exact. Two points are required to determine the two constants for both of these relatioas and in each case the curve determined by any two points passes through the third. Parabolic equations of the type (6) fit the nitrogen-nitrogen (q,s = 1.330, 1.047) bond values' to within 0.14% and when used with the carbon-nitiogen (q,s = 1.582, 1.114) and phosphorus-pbsphorus (4,s = 1.428, 1.816) single and triple bond values' lead to almost exactly the Same predictions for the double bond values as do (I)' and Pauling's' covalent radii development. Thus, (1) and (8) fit the known experhental data equally well. (1
- N/4)'
= q(D
- S)
(8)
By a treatment based upon the molecular orbital method, Couloon' has calculated the bondorders of benzene and graphite to be 1.667 and (8) J. L. Knvonnu. J . C k n . P h y r . , 16, 77 (1847). (4) R Chaton, Bull. roc. chin. &It.. 61,26 (1918). t o 4 digits i. rw mmpuative pur(5) ne dchtion d
POKI. (6) L. h d i o g , "The Nature of the Chemical Bond," Cornel U n i v d t y R@n, Itbro. New Y a k , 1840. (7) C. & Codeon, Proc. Roy. SOS. (Lodor), I6@& 413 (1838).
The Solubility of Sodium Sulfamate in Water BY STEPHEN H.LINING AND P.A. V A N DER MEULEN Sodium sulfamate was first isokted and analyzed by Berglund' in 1878. Its solubility in wat q has been reported2 to be 106 g. per 100 g. of water. Beck' reported its molal volume to be 53.7. No other data relating to the salt appear in the literature. As we wished to use this compound in a study to be reported later we prepared and purified the salt and determined its solubility in water. The density and characteristic X-ray reflection data were also determined. The results of this work are reported below. Experimental Our salt was prepared by starting with amnioriiuni sulfamate which had been purified by recrystallization four times from water. When drip the ammonium sulfamate had a melting point of 132.8 A weighed quantify of this salt was treated with the cal& upotity of standard sodium hydroxide solution. The sogution was evaporated undir reduced pressure at a temperature of 40 to 45' to remove the ammonia and to concentrate the
.
( 1 ) E. Berglund, Bull. roc. chim., [2] I#, 422 (1878). (2) M. E. Cupcry, I d . En#.C k n . , W , 627 (1938). (3) G. Beck, J . p r d r . C k n . , 166, 227 (1840).
