2926
G. FORREST mTOODS AND HERMAN SANDERS [CONTRIBUTION FROM
THE
LABORATORIES O F THE
UNIVERSITY O F
Vol. 69
MARYLAND]
Some Reactions of 2,4-Pentadienal BY
G. FORREST n‘OODS
The preparation of 2,4-pentadienal, the aldehyde of butadiene, was reported by us in an earlier paper,‘ %‘e have continued the study of this substance and herein report on the further characterization of this compound, its utilization in the Diels-LUder reaction, and its reaction with I Iheny lmagnesium bromide. 2,4Pentaclienal is obtained by the following seciuence of reactions in which we have been unable to isolate the unsaturated aldehyde (111). b;e
,~
/CH::
CHz
&I
I
/H
cTEr
CH~
o\d’
OGHS
+
10’
‘OCzHh
I
HOCHz
I
CHO
+I1
L H \ H
I
CHz
CHO
IV
I11
wished to exclude the possibility that the product (IV) might be a cyclobutenal. It was found that 2,4-pentadienal was reduced, although sluggishly, a t room temperature with Raney nickel a t 2-3 atmospheres of hydrogen. Valeraldehyde and n-amyl alcohol were the products identified. These results would seem t o exclude a cyclobutenal since the cyclobutane ring is not opened under these mild conditions but requires a temperature considerably above those used here.* 2,4- Pentadienal can be considered as the aldehyde derivative of butadiene and as such it would be expected to enter into the Diels-Alder reaction with maleic anhydride as shown below CHO
CHO
I
I
RCH
0
CE[
I
CH \CHp IV
+
CH-d &H-C/ “ - A H O \
HzC=CH-CH
I1
+
OHC FH
CH2 \C-CH3
I
-----f
C-CH,i
,
CHz ’
IV
FH’\ C-CHI I/
C-CH,
VI
I1 d&:H%H
butadiene which leads to l-aldehyclo-j-viiili1-1,2dimethyl- A1-cyclohexene (1-1). This was accomplished by heating the reactants in a sealed tube at l t % O
OHC-CH \CH/
C “ 2
I
HERMAKS,!SDERS
HzC=CH-CH
C
