E X P E R I M E N T A L
3
-Cyclohexyl-4-chlorotetrahydropyran.
Into a mixture of 420 g (3.38 moles) of allylcyclohexane and
2
70 g (9 moles) of paraformaldehyde with agitation and cooling to --65 to --70~C was passed a r a p i d stream of
HCI for 4 h. Later the temperature was gradually increased to ~20°C while absorbing the HCI given off with
water. The reaction product was washed with an NaCI solution then with an Na2CO3 solution, dried over Na2-
SO4, and vacuum distilled. The fraction (390 g) with a bp of 105-110°C (4 ram) was 3-cyclohexyl-4-chloro-
tetrabydropyran (Table 1).
Dehydrochlorination of 3-Cyclohexyl-4-chlorotetrahydropyran. In a stainless-steel autoclave was heated
378 g (1.87 moles) of 3-cyclohexyl-4-chlorotetrahydropyran with a solution of 210 g of KOH in 500 ml of
ethanol for 1.5 h at 140~C. After cooling the mixture was poured into water, the organic layer was separated,
the aqueous alcohol layer was extracted with hexane, and the residue was added to the main product. After
vacuum distillation 282 g (91%) of 3-cyclohexyldihydropyran was obtained (see Table 1).
Hydrogenation of 3-Cyc!ohexyldihydropyran. Into a 3800 ml rotating stainless-steel autoclave was
placed 274 g (1.648 moles) of 3-cyclohexyldihydropyran, 150 m[ of ethanol, and 20 ml of an alcoholic Raney
N1 p a s t e . The autoclave was purged with nitrogen and Hz was pumped in to 24 arm. The hydrogenation took
place with slight evolution of heat and basically ended within 1 h. The residual hydrogen p r e s s u r e (13.4 atm)
was released, the autoclave was purged twice with nitrogen (to 5 atm), opened, the contents were drawn off
with a tube connected to a Bunsen bottle while washing off the wall of the autoclave with a mixture of alcohol
and solid CO2 to avoid the evolution of heat from the pyrophoric catalyst. The catalyst was filtered off, the
alcohol was evaporated from the filtrate, and the residue distilled. 3-Cyclohexyltetrahydropyran, 261 g (95%),
was obtained.
2
-Cyclohexyl-l,5-dibromopentane.
Into 251 g (1A9 moles) of 3-cyclohexyltetrahydropyran was quickly
poured with agitation 100 ml (1.05 moles) of PBr3, the mixture was heated to 145-15(rC, and at this tempera-
lure was added 55 ml of 48% HBr within 2.5 h. Then another 10 ml of HBr was added immediately, the mix-
ture was cooled to ~20°C, and 80 ml of benzene was added. The lower acid layer was discarded and the upper
one was neutralized by adding excess solid NazCO3. After filtering through a paper filter* 10 mr- thick and
vacuum distilling off the benzene (100"C, 4 ram), 473 g (95%) of a colorless oil was obtained.
3
-C)rclohexTlthiac~/clohexane. t A t o t a l of 650 ml of an aqueous alcoholic solution of Na2S (from 480 g of
NazS
•
9H20 in 500 ml of H20 and 450 ml of alcohol) and 428 g of unpurffied 2-cyclohexyl-l,5-dtbromope-tane
were added simultaneously over a 40 minute period to a flask containing the remaining I~S~ solution while
mixing and heating, after which the mixture was boiled another 3 h. Upon cooling the upper layer was s e p a -
rated out and the lower aqueous alcoholic layer was extracted with 5 ml of hexane. The hexane extract was
combined with the main product, dried with Na~O4, and fractionally distilled (15 t h e o r , plates).
A t o t a l of 170 g (~70%) of the impure sulfide, bp 64-85°C (2 ram), which was purified by heating with
Na (100"C, 3 h) after which it was filtered and fractionally distilled (15 t h e o r , plates), was obtained.
3
-Cyclohexylthiacyclohexane-l-oxide.
The oxidation of 3-cyclohexylthiacyclohexane was carried out by
the method in [10] with NaIO4 in an aqueous alcoholic solution at 0°C for 5 h. The sulfoxide was recrystallized
from a hexane -- benzene mixture.
3
-Cyclohexylthiacyclohexane-l,l-dioxide.
The oxidation of 3-cyclohexylthiacyclohexane was carried out
by the method in [11] with HzO2 in AcOH (1000C, 1 h). A f t e r neutralization with an alkali the product was ex-
tracted with a benzene -- ether mixture and recrystallized from a benzene -- pentane mixLure.
C O N C L U S I O N S
1
.
A four-step preparative method of preparing 3-alkyl (cycloalkyl)-substltuted thiacyclohexanes
s t a r t i n g from ~-oleflns is proposed.
2
.
An effective method of splitting the cyclic e t he rs and converting them into the dibromides has been
developed.
*
P a p e r filters of any thickness are convenier*ly prepared as follows: Filter paper is soaked in water, ground,
the pulp obtained is transferred to a Buchner funnel or to a sintered glass funnel, the water is sucked off, and
the compact p a p e r filter that is formed is washed with acetone, then with any suitable solvent.
tCarried out by the method in [1].
2147
Volynskii et al.
