Pentaerythritol is converted to its diformal, 2,4,8,10-tetroxaspirol5.5undecane, by heating it to a temperature within the range of about 110 to 150 C, for a period of up to 10 minutes, in the presence of a slight excess of paraformaldehyde and of a catalytic quantity of an acid catalyst such as sulfuric acid. The reaction may be carried out in two steps, by forming first the monoformal, then the diformal. In any case, total reaction time is about 10 minutes, and yield of diformal are greater than 90%. Previous processes require hours or days, and often, tedious operating procedures

Poshkus, A. C.

English

NASA Technical Reports Server

United States Patent [191 [ i l l  Patent Number: 4,528,386 
Poshkus [45] Date of Patent: Jul. 9, 1985 
SYNTHESIS OF 
Inventor: 
Assignee: 
2,4,8,10-TETROXASPIRO[5.5]UNDECANE 
Algirdas C. Poshkus, Lancaster, Pa. 
The United States of America as 
represented by the Administrator of 
the National Aeronautics and Space 
Administration, Washington, D.C. 
Appl. NO.: 183,707 
Filed: Sep. 3, 1980 
Related U.S. Application Data 
Continuation of Ser. No. 54,502, Jul. 3, 1979, aban- 
doned. 
Int. ( 3 . 3  ............................................ C07D 319/00 
us.  c1. .................................................... 549/335 
Field of Search ...................... 260/340.7; 549/335 
References Cited 
U.S. PATENT DOCUMENTS 
1,934,309 11/1933 Hoover ............................ 260/340.7 
2,775,622 12/1956 Snow ................................ 260/340.7 
2,915,530 12/1959 Kray et al. ....................... 260/340.7 
2,945,008 7/1960 Caldwell et al. ................. 260/340.7 
3,092,640 6/1963 Mantell et al. ................... 260/340.7 
4,076,727 2/1978 Rey et al. ..................... 260/340.9 R 
Primary Examiner-Ethel G. Love 
Attorney, Agent, or Firm-Darrell G. Brekke; John R. 
Manning; Robert D. Marchant 
P I  ABSTRACT 
Pentaerythritol can be converted to its diformal, 
2,4,8, IO-tetroxaspiro[5.5]undecane, by heating it to a 
temperature within the range of about 110" to 150" C. 
for a period of up to 10 minutes, in the presence of a 
slight excess of paraformaldehyde and of a catalytic 
quantity of an acid catalyst such as sulfuric acid. The 
reaction may be carried out in two steps, by forming 
first the monoformal, then the diformal. In any case, 
total reaction time is about 10 minutes and yield of 
diformal are greater than 90%. 
Previous processes require hours or days, and often, 
tedious operating procedures. 
6 Claims, No Drawings 
https://ntrs.nasa.gov/search.jsp?R=19850024874 2020-03-22T19:53:23+00:00Z
1 
4,528,3 8 6 
2 
In view of this situation, it is the principal object of 
this invention to provide a process which will be free of 
any and all of the art limitations just enumerated. 
SYNTHESIS OF 
2,4,8,10-TETROXASPIRO[5.5]UNDECANE 
ORIGIN OF THE INVENTION 
The invention described herein was made in the per- 
formance of work under a NASA contract and is sub- 
ject to the provisions of Section 305 of the National 
Aeronautics and Space Act of 1958, Public Law 85-568 
(72 Stat. 435; 42 U.S.C. 2457). 
This is a continuatioin of application Ser. No. 
054,502, filed July 3, 1979, now abandoned. 
BACKGROUND OF THE INVENTION , 
5 SUMMARY OF THE INVENTION 
It has now been discovered that pentaerythritol difor- 
mal can be prepared conveniently in high yield in less 
than 10 minutes, simply by heating a stirred mixture of 
pentaerythritol with paraformaldehyde in slight excess, 
at a temperature of up to about 120" C. in the presence 
of a catalytic quantity of acid, in the absence of any 
solvent except for a small quantity of water. 
DETAILED DESCRIPTION OF THE 
INVENTION 
Id 
1. Field of the Invention To obtain the desired cyclic diformal of pentaerythri- 
The present invention relates to 2,4,8, lO-tetroxas- to], a powdered mixture of the tetrahydroxy compound 
Piro[5.5l-undecane(PentaerYthritol diformal) and more and a slight excess of paraformaldehyde is heated rap- 
particularly to an improved method for its preparation. idly while stirring to a temperature above 100" C. and as 
2. Description of the Prior Art 20 high as 150" C., but preferably within the range of 
Pentaerythritol diformal is readily prepared, often in 1 1Oo-13O0 C. Total heating time lasts from about 5 to 10 
good yield, under acidic conditions from pentaerythri- minutes. During this heating, the mixture turns into a 
to1 and aqueous formaldehyde, trioxane, or paraformal- paste, progressively becoming more fluid as the temper- 
dehyde. Reaction times, however, are in the order of ature rises, and finally turning into a clear liquid at 
several hours or days, and operations for its isolation 25 about 110" C. Between about 105" and 115" C., the 
can be time-consuming. These conventional processes liquid boils as the water of reaction escapes, then it soon 
may be illustrated by that of A. Skrabal et a1 [Z. Physik. becomes quiescent. The clear odorless liquid crystal- 
Chem., 119,305 (1926)l which consists in heating penta- lizes into a solid mass of crystals on cooling. The prod- 
erythritol in trioxane, on a waterbath, for 4 hours in uct suPercools rapidly, evolving an appreciable quan- 
order to obtain a 75% yield of the spirocyclic formal. 30 tity of heat during solidification. It also melts within the 
Formation of the diformal from chloromethyl ethers of range of 35" to 48" C.-in the lower end of the range if 
pentaerythrito] and of 5,5-bis(hydroxymethyl)- 1,3-diox- Some monoformal is Present, and in the upper range, if 
ane has no practical synthetic value [J. Lichtenberger et the reaction has been properly carried Out to minimize 
al, Bull. Sot. Chim. France, 468 (1947)]. As to the reac- fomation of the monoformal. Recrystallization from 
tion of paraformaldehyde with paraldehyde to obtain 35 petroleum ether or distillation will yield the pure com- 
the diformal, it requires at least 30 hours for a 15% yield pound 
steps. First, the reagents are heated to a maximum tem- 
perature of about 120" for about 5 minutes to give the 1131 (1952)l. The more recent efforts in the preparation of various 40 monoformal. After cooling to about 70" and adding the acetals of pentaerythritol still offer no clues on the pos- second molar equivalent of paraformaldehyde, with 
about 1% excess, the mixture is heated again to about sible improvement of the conventional preparations of pentaerythritol diformal. Renner et a1 (US. Pat. No. 1200 for about minutes to convert the monoformal to 3,978,088), for instance, prepare diacetals with dimeric the difomal. In this manner, the total heating time is 
P-oH-pivaldehyde in acid by a 24 hour 45 still about 10 minutes, but formaldehyde losses are mini- 
reaction. Fruhstorfer et a1 (U.S. Pat. No. 3,621,034), on mized and conversion is improved, although yields are 
the other hand, boil pentaerythritol with dodecylthio- in exceSS of 
2,915,530) obtain their diacetals with e.g. acrolein after %, must be present. Examples of usable acids include 
a hour period in the presence Of o*l% phos- 50 hydrochloric, sulfuric, toluenesulfonic, and methanesul- 
phoric acid. fonic acids, as well as boron trifluoride etherate and 
Finally, Zey et a1 (U.S. Pat. NO. 4,076,727) most re- aluminum chloride. Hydrochloric acid is used advanta- 
cently disclosed the preparation of cyclic acetal from geously with zinc &loride, but this acid may be objec- 
Pob'olS, e*g+ trimethYlolProPane and an aldehyde such tionable because of possible formation of the carcino- 
as formaldehyde and butyraldehyde, by refluxing such 55 genic bis(chloromethy1)ether. Cadmium chloride, zinc 
chloride, or phosphoric acid in low concentrations are 
hours. The Possibility of higher temperatures, i.e.9 UP to ineffective; only resinous products or rubbery gels are 
150" c., iS mentioned, solvent permitting it iS assumed. formed from which no diformal can be isolated. How- 
In any event, ZeY et a1 appear to be committed to a ever, when a small quantity of water is used with zinc 
conventional process to obtain the acetals that they 60 chloride, moderate yields of the diformal are produced. 
need for the synthesis of acrylic esters. Although only clear resins or tough rubbery gels are 
In summary, the processes that have just been re- produced with small concentrations of phosphoric acid 
viewed, as well as several other existing approaches, ( < l o  mole %, based on pentaerythritol), with larger 
variously suffer from one or more of the following concentrations of the acid, the diformal is obtained in 
shortcomings, namely: long reaction times-hours or 65 increasingly better yields, e.g. SO% when an equimolar 
days; inferior yield of product; time-consuming proce- quantity of acid is present. 
dures for isolation; use of solvents; high expenditure of If anhydrous acids are used, a small quantity of water, 
energy; and inadaptability to continuous production. about 1% of the total weight of the reactants, is benefi- 
at 500 c. 
by tedious operations [H. J. Prins, Ret. Trav. Chim. 71, The reaction is carried Out in two 
in either case. 
propano1 for 31 hours, while Kray et a1 (u.s. pat. No. Catalytic quantities of acid, i.e. about 0.1 to 1.0 mole 
in, e& benzene for a Period of at least 
4,528,3 8 6 
3 4 
cia1 in that the reagents convert into an easily stirrable paraformaldehyde, 2.0 g, for 15 minutes to get another 
fluid much faster. Heat transfer is thus greatly im- crop of diformal, 6.5 g, mp 48"-50" C. 
EXAMPLE 5 proved. Aside from this convenience, water is not es- sential for good yield of product. 
Instead of paraformaldehyde, trioxane is considera- 5 p-Toluenesulfonic acid, 0.2 g, was mixed with pow- 
bly more expensive and, when the reaction is incom- dered pentaerythritol, 13.6 g, and paraformaldehyde, 
plete, difficult to separate from the diformal. Formalin, 6.2 g, and heated to 150" C. for a total time of 15 minutes 
Le. 40% aqueous formaldehyde, gives the diformal as to get the crude diformal, 15.5 g, mp 37"-42" C. 
the art shows, but the reaction takes longer due to EXAMPLE 6 longer boiling to remove water and some diformal is 10 
lost in the water vapor. Zinc chloride, 0.3 g, and water, 4 drops, were mixed 
The following examples will now illustrate the prac- with pentaerythritol, 13.6 g, and paraformaldehyde, 6.8 
tice of the invention in operational detail. In all the g. This reaction mixture was heated in 3 minutes to 90" 
preparations described, the reagents are of commercial C., when it became a putty-like mass, and then a paste at 
quality and are employed as received, except for occa- 15 loo" C. At 120"-125' C., the viscous bubbling paste 
sional powdering of solids, as necessary. turned into a clear liquid after 10 minutes. The tempera- 
ture was raised to 145" C. for 3 minutes, and the pale 
brown liquid cooled to a waxy solid, 14.8 g, mp 38"-43" 
A mixture of pentaerythritol, 40.8 g, paraformalde- C. The diformal, 10.4 g, mp 49"-50" C., was extracted 
hyde, 20 g, and sulfuric acid, 5 drops, was heated to 20 from this wax with petroleum ether. When water was 
145" C. in about 10 minutes and maintained at this tem- excluded from this reaction mixture, only 0.8 g of the 
perature until ebullition ceased, about 5 minutes. On diformal could be extracted from the viscous reaction 
cooling to room temperature, the clear liquid obtained product. 
EXAMPLE 7 solidified exothermally into a crystalline mass weighing 48.6 g. Extraction with boiling petroleum ether and 25 
distillation of the extracts left the diformal as white Pentaerythritol, 13.6 g, paraformaldehyde, 6.9 g, and 
needles, 33.5 g, mp 49"-50". The immiscible oil remain- 85% phosphoric acid, 11.0 g, were heated up to 150" C. 
ing was mixed with paraformaldehyde, 1.5 g, and for a total time of 10 minutes. The diformal was ex- 
heated rapidly to 150" C. for a total of 10 minutes. tracted from the resultant ether miscible viscous oil 
Work-up as before gave a second crop of diformal, 11.2 30 with methylene chloride for a yield of 12.5 g, mp 
g, mp 49"-50" C., for a total yield of 92% based on the 4e-48" C. 
EXAMPLE 1 
pentaerythritol. 
EXAMPLE 2 
A mixture of pentaerythritol, 13.0 g, paraformalde- 
hyde, 3.1 g, and 25% sulfuric acid, 2.0 g, was heated in 
1 minute to 105" C. The paste, initially formed at 65" C., 
became a thin slurry at 70" C. and a clear liquid at 105" 
C. After 2 minutes at 105"-1 10" C. and another 2 min- 
utes at 115"-120" C., the liquid was cooled to 80" C. and 
additional paraformaldehyde, 3.1 g, was added. Heating 
was continued as before, and the reaction mixture then 
cooled to get a crystalline white solid, 15.8 g, mp 
45O-48" C., which after extraction with petroleum ether 
gave 14.5 g of the diformal. 
EXAMPLE 3 
A mixture of paraformaldehyde, 7.0 g, pentaerythri- 
tol, 13.6 g, zinc chloride, 0.6 g, and concentrated hydro- 
chloric acid, 1.0 ml, was heated in 4 minutes to 100" C. 
to give a clear liquid which boiled at 114" C. for 2 min- 
utes and was quiescent at 120" C. for 2 minutes. On 
cooling, it solidified to a solid cake, 16.8 g, mp 42"-48" 
C. A solution of the product was treated with charcoal 
and sodium carbonate and filtered to remove the zinc 
chloride. Distillation of the solvent left the diformal, 
15.7 g, mp 46"-48" C. 
EXAMPLE 4 
A mixture of pentaerythritol, 27.2 g, paraformalde- 
hyde, 13.6 g, methanesulfonic acid, 5 drops, was heated 
to 150"-160" C. in 15 minutes and maintained at this 
temperature for a total heating time of 30 minutes. The 
liquid solidified to a white waxy solid, 28.0 g. Extrac- 
tion with petroleum ether and distillation of the extracts 
left the diformal, 22.9 g, mp 49"-50" C. The oily residue, 
immiscible in petroleum ether, was combined with the 
similar oil from an earlier run, 2.0 g, and heated with 
EXAMPLE 8 
Repeating the procedure of Example 7 with only 0.3 
35 g of the phosphoric acid and heating for a total time of 
12 minutes yielded a very viscous oil which on cooling 
became a tacky cololess resin, 15.6 g, insoluble in either 
methylene chloride or ether. No diformal was found. 
EXAMPLE 9 
A mixture of pentaerythritol, 13.6 g, paraformalde- 
hyde, 6.2 g, and boron trifluoride etherate, 4 drops, was 
heated in 4 minutes to 105" C. to give a clear liquid. At 
120" C., boiling occurred, which ceased in about 5 min- 
45 utes, after which the temperature was held at 130" C. 
for 3 minutes. When the liquid cooled, the oily crystal- 
line product was extracted with petroleum ether to 
yield the diformal, 9.1 g, mp 48"-49" C. 
EXAMPLE 10 
Pentaerythritol, 13.6 g, paraformaldehyde, 3.1 g, 
sulfuric acid, 0.5 g, and water, 1.5 g, were heated to- 
gether to form a paste in 0.5 minute at 65" C. and a thin 
slurry at 90" C. in 1 minute. At 100"-1 10" C., the slurry 
55 was converted into a clear liquid in 0.5 minute. Heating 
at 100"-110" C. was continued for 2 minutes and finally 
at 115"-120" C. for another 2 minutes. The liquid, 16.1 
g, was cooled to about 60" C. and paraformaldehyde, 
3.1 g, added. The slurry was heated at 1 10" C. to obtain 
60 a clear liquid and then for about 2 minutes at 115"-125" 
C., for a total heating time of 5 minutes. The liquid 
solidified to a white crystalline mass, 15.8 g, mp 45"-48" 
C. 
EXAMPLE 11 
A mixture of trioxane, 6.3 g, pentaerythritol, 13.6 g, 
and sulfuric acid, 4 drops, was heated rapidly to a thin 
slurry at 100" C. that clarified within 5 minutes at 110" 
40 
50 
65 
4,528,3 86 
5 6 
C. The temperature was raised to 150" C., during which to a temperature between about 105" and 150" C. 
time much boiling occurred but soon subsided, heating thereby causing the mixture to liquify and continuing 
was continued for 5 .minutes. The total heating time was such heating for a total period of about 3 to 20 minutes 
20 minutes. The diformd 5.7 g, mP 48O-50" c., was to cause and complete the reaction of pentaerythritol 
extracted with petroleum ether. The oil immiscible with 5 with paraformaldehyde to produce the diformal of pen- 
Petroleum ether* 8.6 g* was heated to 1550 c. taerythritol, and during such heating allowing the water 
with paraformaldehyde, 1.5 g, for a total heating time of resulting from the reaction to evaporate. 
weight of water is present in the reaction mixture. mp 48"-50" C. 
wherein about o.l to l.o 
mole %, based on the pentaerythritol of an acid catalyst advantages over the processes of the art in terms of 
shortened reaction times in the order of 3 to 20 minutes, is used, said acid catalyst being selected from the group yields greater than 90%, elimination of solvents, de- consisting of sulfuric acid, hydrochloric acid, methane- crease in labor and energy requirements, adaptability to sulfonic acid, p-toluenesulfonic acid, boron trifluoride continuous operations, and overall simplicity and con- 15 
venience, The product, of can be used for its etherate, zinc chloride, aluminum chloride, and mix- 
conventional purposes which, inter alia, include con- tures thereof. 
aphrogenic and pyrostatic phosphorylated derivatives, concentrated aqueous phosphoric acid present in a con- 
and the like. It is further contemplated that many varia- 20 centration greater than 10 mole % based on the Penta- 
tions can be carried out by the man skilled in the art 
without departing from the limits of the present inven- 5. The process of claim 1 wherein the reaction is 
tion as claimed. carried out in two stages, with about one-half of the 
What is claimed is: paraformaldehyde being added at each stage and heated 
1. A process for the preparation of the cyclic diformal 25 With the other components for a Period about half as 
10% as the total heating time. 
6. The process of claim 1 wherein the reaction is 
carried at a temperature within the range of about 110" 
to 130" C. for a period of up to 10 minutes. 
lo minutes to get a second crop Of the diformal, 6*7 g, 2. The process of claim 1 wherein up to about 1% by 
The improved process of the invention has several 10 3, The process of claim 
version into ethylenically unsaturated monomers, into 4* The process Of claim wherein the acid is 
of pentaerythritol, which comprises providing a mix- 
ture of pentaerythritol and paraformaldehyde in ap- 
proximately stoichiometric proportions, such mixture 
being substantially anhydrous and solvent-free, and 
heating such mixture in the presence of an acid catalyst 30 * * * * *  
35 
40 
45 
50 
55 
60 
65 


Synthesis of 2,4,8,10-tetroxaspiro5,5undecane

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