Lipschitz, A

Lucas, D

English

NASA Technical Reports Server

SYNTHESIS AND HYDROLYSIS-RATE STUDIES OF 
Lewis Flight Propulsion Laboratory 
Cleveland, Ohio 
FOR AERONAUTICS 
I 
WASHINGTON 
October 8, 1957, 
https://ntrs.nasa.gov/search.jsp?R=19930089870 2020-06-17T06:31:00+00:00Z
0 
m 
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NACA RM E57H07 
NATIONAL ADVISORY COMMITTEE F 9 R  AE3ONAUTICS 
RESEARCH MEMORANDUM 
SYNTHESIS AND HYDROLYSIS-RATE STUDIES OF DECABORANE DERIVATIVES 
By D. Lucas and A .  Lipsciiitz 
SUMMARY 
A s e r i e s  of experloents Ifivolving tkie reaczion of water with 
decaborane and " - 3 ,  a bOrGn f u e l  csns is t ing  mainly of ethyldecaborane, 
~ ' 3 s  performed. The r e s u l t s  show t h a t  t he  presence o f  one alkyl group on 
t h e  decaborane nucleus lnhibLts the hydrolysis reac t ion  s ign j f i can t ly  and 
t h a t  t h e  hydrolysis r a t e  can be increased by using an ac id i c  hydrolysis 
mixture. 
mediates i n  proposed dimethyldecaborane syntceses , and t h e i r  a e l t i n g  
points ,  molecular weights, and s o l u b i l i t i e s  i n  c e r t a i n  solvents  were 
determined. 
these  iodo isomers and methyl magnesium bromide, methyl l i thium, o r  methyl 
bromide. 
Two diiododecaborane isomers were prepared f o r  use as i n t e r -  
No dimethyldecaborane resu l ted  from the reac t ion  between 
INT!RODUCTION 
One of t he  problems i n  using boron-containing f u e l s  i s  that of s t o r -  
age and handling. Since most borori hjrdrides hydrolyze on exposure t o  
water, s p e c i f i c  knowledge of the hydrolysis reac t ion  of a boron-containing 
f u e l  is  des i rab le .  Therefore, a se r i e s  of hydrolysis experiments was 
performed a t  the  NACA Lewis laboratory on HEF-3, a high-energy f u e l  con- 
s i s t i n g  mostly of ethyldecaborane with some d i -  and trietby'decaborane. 
These experiments involved the  react ion of " - 3 ,  or decaborane, and water 
i n  e i t h e r  dioxane or e t h y l  alcohol and were var ied  by the  addi t ion  of 
sodium hydroxide and f e r r i c  ch lor ide .  
evolved with time w a s  measured. It was concluded t h a t  more information 
could be obtained by repeat ing the  hydrolysis with an a lkyla ted  decaborane 
i n  a more highly pu r i f i ed  form than tha t  of HEF-3. 
I n  a l l  cases,  t he  volume of gas 
The present  methods of preparing alkyldecaboranes a r e  such t h a t  the  
products a r e  mlxtures of mono-, di- ,  and triaikyldecaboranes with physical  
and chemical proper t ies  s i m i l a r  enough t o  make a complete separat ion d i f -  
f i c u l t .  This d i f f i c u l t y  possibly might be avoided by csing a halogenated 
decaborane as an intermediate.  A compound sucn as diiododecaborane could 
be puriyied by r e c r y s t a l l i z a t i o n  and then might r e a c t  with an a lky la t ing  
agent t h a t  would replace the  halogens on the  decaborane nucleus with a lky l  
groups. 
2 CONFIDENTIAL NACA RM E57H07 
Halogenated boranes have been known s ince  Alfred Stock 's  o r i g i n a l  
work on the boron hydrides i n  t he  1920's.  A diiododecaborane w a s  f i r s t  
prepared i n  1929 (ref.  1, p. 98) .  
by Gale and Wagner ( ref .  2 ) ,  and the  s t r u c t u r e  and t h e  melting poin t  of 
t he  diiododecaborane were determined. 
This preparat ion w a s  repeated i n  1955 
Since dimethyldecaborane is  of i n t e r e s t  not only f o r  i t s  hydrolysis  
r eac t ion  but  a l s o  as a poss ib le  high-energy f u e l ,  it was decided t o  attempt 
i t s  synthesis by us ing  diiododecaborane as an intermediate .  Because boron 
hydrides have c e r t a i n  similarities t o  organic compounds i n  t h e i r  r eac t ions ,  
t h e  organic methylating agents methyl magnesium bromide, methyl l i thium, 
and methyl bromide were se l ec t ed  as compounds t h a t  might be e f f e c t i v e  i n  
preparing dime thy lde  cabor ane . 
HYDROLYSIS OF DECBORANE DERIVATIVE3 
Apparatus and Procedure 
The apparatus used i n  a l l  t h e  hydrolysis  experiments i s  shown i n  
C .  The homogeneous hydrolyzing medium, which w a s  var ied  as shown i n  t a b l e  
I, w a s  introduced i n t o  t h e  r eac t ion  f l a s k ,  and 0.3 m i l l i l i t e r  of HEF-3 
(NACA f u e l  5528) w a s  added. In  one experiment, 0.1806 g r a m  of decaborane 
r e c r y s t a l l i z e d  from e t h y l  ace t a t e  w a s  used ins tead  of HEF-3. I f  HEF-3 i s  
assumed t o  be 100 percent ethyldecaborane, t h i s  i s  comparing t h e  r eac t ion  
of 1.64X10-3 moles of "-3 with 1.476X10-3 moles of decaborane. 
progress of t he  r eac t ion  w a s  observed by measuring t h e  volume of gas 
co l lec ted  i n  t h e  gas b u r e t t e  as a funct ion of time. Corrections were made 
f o r  t he  vapor pressure of the hydrolyzing mixture, and the  d a t a  were r e -  
duced t o  s tandard temperature and pressure .  
f i gu re  1. The constant-temperature water ba th  w a s  maintained at 3 5 . a o + 0 . 3 O  - 
4 
The 
Resul ts  and Discussion 
Table I l is ts  t h e  moles of gas per mole of boron hydride t h a t  were 
evolved i n  each of t he  hydrolysis  reac t ions  during running time and a l s o  
gives  a n  idea of the  completeness of t h e  r eac t ion  by comparing these  r e -  
s u l t s  with the  expected number of moles of gas. Analyses of t h e  gas 
evolved during t h e  hydrolyses of HEF-3 and decaborane have shown the  
presence of hydrogen only. The equation f o r  t he  complete hydrolysis  of 
decaborane may be w r i t t e n  as follows: 
B10H14 + 30 H20 -+ 10 B(OH)3 + 22 Hz 
If HJ3F-3 i s  assumed t o  be 100 percent ethyldecabdPane, a s i m i l a r  
equation may be wr i t t en  f o r  i t s  hydrolysis :  
NACA RM E57HO7 CONFIDENTIAL 3 
Y 
P 
s 
r 4  
8 
. 
The rate of t h e  hydrolysis  reac t ions  i s  shown by the s lopes of t he  
curves i n  figure 2 ( a ) ,  where t h e  volume of gas evolved is p l o t t e d  aga ins t  
t i m e .  
may be used more r ead i ly  t o  determine the  i n i t i a l  rates. It w i l l  be noted 
t h a t ,  i n  a l l  t h e  reac t ions ,  t h e  rate reaches a break point  after the first 
f e w  hours and then decreases t o  a more gradual rate. 
Figure 2(b) ,  which shows an expanded view of p a r t  of figure Z(a), 
Hydrolysis of boron hydr ides  has been described as the  addi t ion  of 
The present d a t a  show that t h e  rate of 
In f igu re  3, the  
the nucleophi l ic  por t ion  of t h e  water molecule t o  boron and t h e  subsequent 
release of a hydrogen (ref. 3 ) .  
hydrolysis  depends on the pH of t h e  hydrolyt ic  aedium. The pH of 
each of t h e  hydrolyt ic  so lu t ions  is given i n  t a b l e  I. 
l o g u i t h m s  of t h e  i n i t i a l  r a t e s ,  taken as t h e  i n i t i a l  slopes of t he  l i n e s  
of f i g u r e  2, are p l o t t e d  against  pH. This p l o t  may be expressed as 
Rate of hydroiysis (1) 
where the exponent k has a value of about 0.2.  
The i n i t i a l  hydrolysis  rate seems t o  be constant,  s ince gas i s  
evolved at a f a i r l y  constant rate during t h e  i n i t i a l  reac t ion .  
t h e  ra te  apparently i s  independent of €El?-3 concentration and, if the  
hydrogen ion takes  p a r t  only as a ca t a lys t ,  i t s  concentration does not 
change. This i n t e r p r e t a t i o n  may be used t o  explain the  occurrence of 
breaks i n  t h e  l i n e s  of f i g u r e  2; t he  hydrolysis continues at a constant 
r a t e  f i x e d  by the  hydrogen-ion concentration u n t i l  a l l  the  HEF-3 is  con- 
ve r t ed  t o  a l e s s  r eac t ive  form. The l e s s  r e a c t i v e  form may r e s u l t  from 
a t t a c k  and replacement a t  the s i n g l e  active-hydrogen s i t e  t h a t  probably 
remains i n  monoalkylated decaborane . 
ac t ive  hydrogens (ref. 4), one of which i s  probably replaced by the e t h y l  
group i n  etbyldecaborane . ) 
Therefore, 
(Decaborane i t s e l f  has two espec ia l ly  
The curve f o r  decaborane exh ib i t s  t w o  break points ,  one at about 2 
hours and the  other a t  about 7 l  hours ( f i g .  2(a) . Since t h e  decaborane 
molecule has two espec ia l ly  r eac t ive  hydrogens, t he  two break poin ts  may 
be due t o  t h e  replacement of one of these, followed by a t t ack  on the 
second a t  a reduced r a t e .  
z 
This explanation of HEF-3 hydrolysis, which pos tu la tes  t he  formation 
of a l e s s  r eac t ive  form of ethyldecaborane, a l s o  would seem t o  p red ic t  
that  equivalent amounts of gas woi.ld have evolved by t h e  t i m e  t h e  break 
poin t  i n  t h e  hydrolysis occurred; f igure 2 shows that  t h i s  i s  not t h e  
case.  However, it may be s i g n i f i c a n t  that t h e  ex ten t  of reac t ion ,  as 
shown i n  t a b l e  I, roughly follows the same order  of pH f o r  t h e  var ious 
hydro ly t ic  media used i n  HEF-3 hydrolysis.  It i s  evident tha t  more work 
is requi red  before the  hydrolysis  of decaborane der iva t ives  can be f u l l y  
under stood. 
4 C O N F I D r n L A L  NACA RM E57H07 
Since the  presence of one a l k y l  group on t h e  decaborane nucleus in-  
h i b i t s  the hydrolysis reac t ion ,  t he  prepara t ion  of a dialkyldecaborane . 
w a s  believed t o  be worthwhile i n  order t o  see if t h i s  r e s i s t ance  t o  
hydrolysis increased with the  number of a l k y l  groups. A pure a lkyla ted  
boron hydride was a l s o  desired f o r  such s tud ie s ,  inasmuch as t h e  e f f e c t s  
of impurit ies i n  HEF-3 on the  hydrolysis  rate were not  known. Attempts 
accordingly were made t o  prepare dimethyldecaborane, as described i n  the  
following sec t ion .  
BORON HYDRIDE SYNTHESIS 
Preparat ion of Diiododecaborane 
This synthes is  of diiododecaborane i s  a r e p e t i t i o n  of S tock ' s  o r ig -  
i n a l  preparation ( r e f .  1, p.  9E). A 2.1-gram (0.0171 mole) sample of 
decaborane w a s  heated i n  a sea led  500-mi l l i l i t e r  f l a s k  with 9 . 3  g r a m  
(0.0360 mole) of iodine f o r  19* hours a t  110' C u n t i l  only a s m a l l  amount 
of iodine vapor w a s  v i s i b l e  i n  t h e  f l a s k .  The f l a s k  w a s  opened, and t h e  
s o l i d  reac t ion  product w a s  ex t rac ted  with 200 m i l l i l i t e r s  of carbon d i -  
s u l f i d e ,  t r e a t e d  with mercury t o  remove any unreacted iodine,  and f i l t e r e d  
t o  remove insoluble  higher iodinat ion products.  The carbon d i su l€ ide  w a s  
removed under vacuum, and the  3.9 g r a m s  of yellow s o l i d  res idue was re- 
c r y s t a l l i z e d  from benzene t o  y i e l d  0.3 gram of a yellow c r y s t a l l i n e  mate- 
r i a l  tha t  melted at 234' t o  237' C .  n-Heptane w a s  added t o  the  benzene 
solut ion,  and 3.4 grams of yellow c r y s t a l s  melting a t  135' t o  140° C w a s  
obtained. Analysis of both samples f o r  percent iodine agreed with t h a t  
ca lcu la ted  f o r  diiododecaborane, as shown i n  t a b l e  11. Only t h e  higher 
melting-point isomer has been reported previously (refs. 1 (p.  98) and 2 ) .  
-. 
Reactions o f  Diiododecaborane Isomers 
With methyl magnesium bromide. - To a so lu t ion  containing 7 . 1  grams 
of diiododecaborane (0.0190 moles; m . p . ,  1 3 5 O  t o  1-40' C) i n  200 m i l l i -  
liters of anhydrous e t h y l  e the r ,  21 mili i l i ters  of an e the r  so lu t ion  of 
methyl magnesium bromide (0.0380 mole) were added gradually over a 1/2- 
hour period. During t h i s  t i m e ,  gas s t e a d i l y  evolved from t h e  so lu t ion .  
A t  f i r s t  a f i n e l y  divided white p r e c i p i t a t e  t h a t  s e t t l e d  t o  t h e  bottom of 
t h e  f l a s k  appeared, and the  yellow color  of t h e  so lu t ion  faded; a viscous 
yellow-brown mass gradually accumulated i n  t h e  bottom of the  f l a s k .  
t h e  end o f  1/2 hour, t h e  contents of t h e  f l a s k  were poured i n t o  a mixture 
of 100 m i l l i l i t e r s  of 6 N  HC1 and 50 grams of i ce ;  t h e  viscous yellow- 
brown mass dissolved a t  t h i s  po in t .  The e the r  layer ,  a s l i g h t l y  cloudy 
yellow-orange so lu t ion ,  w a s  separated and d r i ed  over anhydrous calcium 
s u l f a t e .  The e the r  w a s  evaporated under reduced pressure,  and a f laky 
yellow so l id  remained. A carbon t e t r a c h l o r i d e  ex t r ac t ion  of t h i s  s o l i d  
showed tha t  only a s m a l l  amount of t h e  s o l i d  w a s  so luble  i n  carbon 
t e t r ach lo r ide .  
A t  
NACA RM E57H07 C O N F I D r n U u ;  5 
This e-er b e n t  was repeated w i t h  2 .7  grams of diiododecaborane 
(0.0072 mole; m.p., 234' t o  237' C) and 8 m i l l i l i t e r s  of an e the r  so lu-  
t i o n  of methyl magnesium bromide (0.0152 mole). The reac t ion  and the  re- 
s u l t s  observed were the same as those described f o r  t he  low-melting-point 
isomer; only a yellow s o l i d  w a s  recovered from t h e  r eac t ion  mixture on 
evaporation of t h e  solvent .  
With methyl l i thium. - A so lu t ion  containing 5.5 grams of  diiodo- 
decaborane (0.0015 mole; m.p., 135' t o  140' C) i n  200 m i l l i l i t e r s  of 
anhydrous e t h y l  e t h e r  w a s  prepared, and an e the r  so lu t ion  of methyl l i th ium 
w a s  made from methyl bromide and l i thium according t o  t h e  method of Gilman 
and Jones ( r e f .  5, ch. 7 ) .  Then 22 .0  mil l i l i ters  of t h i s  methyl l i th ium 
so lu t ion  (0.00294 mole) were added t o  the diiododecaborane so lu t ion  over 
a per iod of 20 minutes, and the  resu l t ing  so lu t ion  w a s  ref luxed f o r  1 hour. 
A white p r e c i p i t a t e  formed during t h e  addi t ion of t h e  methyl l i th ium solu- 
t i o n ,  and gas evolved s t ead i ly .  The ether  w a s  d i s t i l l e d  off  under reduced 
pressure and a s o l i d  pa le  yellow residue w a s  l e f t .  
obtained. 
NG l i q u i d  product was 
This experiment w a s  repeated with 0.2 g r a m  of diiododecaborane 
(m.p., 234O t o  237O C) and 2 m i l l i l i t e r s  of the  methyl l i th ium so lu t ion .  
This reac t ion  followed the  same pa t t e rn  as t h a t  of t h e  low-melting-point 
isomer b u t  r e s u l t e d  i n  t h e  formation of a co lo r l e s s  r eac t ion  mixture and 
a white res idue .  
With methyl bromide. - No v i s i b l e  r eac t ion  occurred when 1.9 grams 
of diiododecaborane (0.00508 mole; m . p . ,  135' t o  140° C) and 1.5 g r a m s  
of methyl bromide (0.0158 mole) were heated i n  a 520-mi l l i l i t e r  f i a s k  a t  
110' C fo r  a t o t a l  time of 46 hours. 
Resul ts  and Discussion 
No d l f f i c u l t y  arose during t h e  preparat ion of diiododecaborane. The 
resu l t s  of t he  melting-point, molecular-weight, and percent-iodine de te r -  
minations made on t h e  two diiododecaborane isomers are given i n  t a b l e  11, 
and the  r e s u l t s  of c e r t a i n  s o l u b i l i t y  determinations are presented i n  
t a b l e  111. The lower melting-point isomer w a s  much more so luble  i n  a l l  
t h e  so lvents  t r i e d  than t h e  high melting-point isomer. 
Dimethyldecaborane is  a co lo r l e s s  l i q u i d  wi th  t h e  consistency of a 
l i g h t  o i l  at room temperature ( r e f .  6 ) .  No l i q u i d  product w a s  i s o l a t e d  i n  
any of t h e  r eac t ions  between t h e  diiododecaborane isomers and methyl mag- 
nesium bromide, methyl l i thium, o r  methyl bromide. Since t h e  synthes is  of 
dimethyldecaborane w a s  t he  p r inc ipa l  i n t e r e s t ,  no organized e f f o r t s  w e r e  
made t o  determine what t h e  s o l i d  reac t ion  products were. 
6 
CONCLUDING REMARKS 
NACA RM E57H07 
Hydrolysis-rate experiments conducted on decaborane and "-3 showed 
t h a t  the rate of HEF-3 hydrolysis  v a r i e s  wi th  t h e  pH of t h e  hydro ly t ic  
medium and i s  t h e  highest  i n  f e r r i c  ch lor ide  and water, somewhat less i n  
water, and least i n  a sodium hydroxide so lu t ion .  
Two diiododecaborane isomers a r e  formed when iodine and decaborane 
The higher melting-point isomer i s  the  only one previ -  
are reacted together ,  one melting at 135' t o  140° C ,  and the  o ther  at 
234' t o  237' C .  
ously reported.  
Under t h e  condi t ions used, dimethyldecaborane cannot be prepared by 
a reac t ion  between e i t h e r  of t h e  diiododecaborane isomers and methyl 
magnesium bromide, methyl l i thium, o r  methyl bromide. 
Lewis F l igh t  Propulsion Laboratory 
National Advisory Committee f o r  Aeronautics 
Cleveland, Ohio, August 8, 1957 
REFERENCES 
1. Stock, Alfred, und Pohland, Erich: Zur Kenntnis des BloH14. B e r .  D. 
Chem. Gesel lschaft ,  Jahrg.  62, N r .  1, Jan.  9, 1929, pp. 90-99. 
2 .  Gale, W. A . ,  and Wagner, R .  I.: Study of Reactions of Boron-Halogen 
Compounds with Organo-Metallic Compounds. Rep. No. CCC-1024-TR-108, 
P r o j .  Zip, Cal lery Chem. Co., May 5, 1955. (Navy Contract N O a ( s )  
52-1024-c.) 
3. Meeker, T.  R . :  A Kinet ic  Study of t he  Alcoholysis of Decaborane. 
Tech. Res. Rep. No. MCC-1023-TR-206, Univ. of Delaware, June 1956. 
4 .  Schaeffer, Riley: The Molecular S t ruc ture  of BloH1212. Jour .  Am. 
Chem. SOC., vol .  79, no. 11, June 5, 1957, pp. 2726-2728. 
5. Jones, Reuben G . ,  and Gilman, Henry: The Halogen-Metal Interconversion 
Reaction with Organolithium Compounds. Vol. V I  of Organic Reac- 
t ions ,  ch.  7, Roger Adams, e t  a l . ,  eds., John Wiley &Sons, Inc. ,  
1951, pp. 339-366. 
6 .  Garre t t ,  A. B . ,  and H a r r i s ,  Samuel: F r i ede l  - Crafts Synthesis of 
(Contract 
Methylpentaborane-9 and Dimethyldecaborane. Tech. R e s .  Rep. MCC- 
1023-TR-96, Olin Mathieson Chem. Corp., Nov. 8, 1954. 
NOa( s)  52-1023c, Bur .  Aero., Dept . Navy. ) 
CONFIDENTIAL 
. 
NACA RM E57H07 CONFIDENTIAL 
m 
o r l r l m  
L O C O O N  
N * d c t -  
H 
g 
d a 
r l r l r l r l  
E E B 6  
L D l n m m  
N N N N  
z 
rl 
E 
m 
0 
cu 
N 
7 
CONFIDENTIAL 
8 
Low-melting- High-melt ing- 
point point isomer 
comlDmIAL NACA RM E57H07 
- 
TABLE 11. - FROPERTIES OF DIIODODECABORANE ISOMERS 
Calculated 
value 
Property 
13So-14O0 C 
a305 
70.5 
Melt ing point 
Molecular w e i g h t  
Percent iodine 
234'-237' C 
3az 374.1 
68.5 67.8 
I I I 
aProbably low because of decomposition of sample. 
TABLE 111. - ORDER OF SOLUBILITY OF DIIODODECABORANE 
ISOMEFIS IN VARIOUS SOLVENTS 
Solvent 
Acetone 
95 Percent ethanol 
Benzene 
Ether 
Carbon disulf ide 
Chloroform 
Carbon te t rachlor ide 
n-Heptane - 
Remarks 
Soluble with decomposition 
Soluble with decomposition 
If 
C 
c 
C 
. c 
CONFIDENTIAL 
NACA RM ES’j’H07 
. 
CONFIDENTIAL 9 
Open- end 
manometer 
r 
To constant- 
temperature 
bath 
,- Gas bure t te  
1-mm Tubing 
Cent 
PmP 
Figure 1. - Hydrolysis apparatus. 
CONFIDENTIAL 
10 CONFIDENTIAL NACA RM E57H07 
. 
. 
. 
. 
NACA RM E57H07 
~~ 
CONFIDEMlIAL 11 
Figure  2. - Concluded. HEF-3 and decaborane hydrolys is .  
CONFIDENTIAL 
12 
loo I 
80 ~ 
CONFIDENTIAL NACA RM E57H07 
. -+ 
60 
40 
20 
10 
8 
6 
4 
2 
1 
\ 
\ 
4 2 
PK 
Figure 3. - Varia t ion  of rate of HEF-3 hydro lys is  wi th  pH. 
C O r n I D r n I A L  
NACA - Langley Field, VP. 


Synthesis and hydrolysis-rate studies of decaborane derivatives

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