S Y N T H E S I S OF ) ' - D I K E T O N E S BY THE M E T H O D

OF C O N J U G A T E D H Y D R O G E N O L Y S I S

(UDC 542.97)

N. I . S h u i k i n , I . F. B e l ' s k i i , R. A. K a r a k h a n o v , a n d A. A. N a z a r y a n

N. D. Zelinskii Institute of Organic Chemistry, Academy of Sciences, USSR Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 4, pp. 750-751, April, 1964

Original a r t i c le submitted August 12, 1963

As was shown in our previous works [1, 2], 7-d ike tones (III) are formed together with tetrahydrofurans (IV) in the hydrogenation of 7-furyla lkanols (I) in the vapor phase

H~ , Pt~-C - - C - - c - - - - C - - C - - - - R :"- C ' - - C - - C - - C - - C - - c - - C - - R

c-c- -R ~ z o . L oH OH .J "2 II II OH 0 0

(I) (it) ~-H2o (m:~

f ly ) c - - c - - c R

Since there is a reversible process (II) ~(I I I ) in the react ion zone, which is substantially influenced by the t empera - ture, obviously, the condition promoting the formation of ?~-diketones is increased temperature. Actual ly, at 200- 230 ~ diketones are prac t ica l ly not formed, while tetrahydrofurans are obtained in high yields 70-90%)[1]. Al -

though increasing the temperature promotes the formation of diketones, however, it is impossible to signif icantly increase their y ie ld in this way, in view of the reversibi l i ty of the reaction (II) ~ ( I I I ) and the i rreversibi l i ty of the react ion ( I I )~ ( IV) . The average yie ld of 7-diketones on P t - C at 300 ~ is only 30-35% As for the structure of the 7 -diketones formed, hydrogenolysis of the furan ring in (I) at the C - O bond away from the substituent leads to di- ketones containing the n-propyl and alkyl (R) radicals outside the dicarbonyl group.

This work established the possibil i ty of synthesizing 7-diketones by the method of conjugated hydrogenolysis, consequently of more var ied structure, since in this case methyl , ethyl, and n-propyl groups are formed from the carbon atoms of the furan ring

t

Ni - -A I , H 2 ~ 240"

-s-X;'2/~-C--C--~ - R - Bond c l e a v a g e OH

R : C H a , C2H s

1,5 C--C--C--C--C--C--C--R

O , 5 - 4 , s C--C--C--C--C--C--R

1 I 0 0

O . O

Conjugated hydrogenolysis occurs in the case of hydrogenation in the vapor phase on a skeletal Ni--A1 catalyst . How- ever, h'ere too the summary yield of a l l three diketones does not exceed 30-35%. The bulk of the ca ta lyza te is made up of homologs of furan and tetrahydrofuran [3].

EX P E R I M E N T A L

1-Furylalkanols-3 were produced by hydrogenation of furfurylidenemethyl alkyl ketones in an autoclave at 120-130 ~ on a skeletal C u - A 1 catalyst [4]. The preparation of the skeletal N i - A 1 catalyst was described ear l ier[5] .

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Yield and Properties of 7/-Diketones

7 -Dike- tones

Hexane-

d i o n e - 2 , 5

Heptane- dione-2,5

Octane- dione-2,5

Octane- dione-3,6

Nonane- dione-3,6

lqeld, %

12

10--t~

t3

7

13

B.p., ~ mm of mercury)

20 nD

20 d 4

t 194--t95(76t)/t, 4472 O, 999~

/ 76--77(tl) ~ ] 83--84(tt) 11,446610,932~

86--87(tt) 1t,442510, 9652

9 2 - - 9 3 ( I I ) , / - - I -

MR

Foun+a lc ,

Found, % Calc., %

C H O II

M.p. of crys- talline der- ivatives, ~

30,5129,9263,t8 8,7263, t3 8,83

34,6334,5465,67 9,41 65,591 9,47

,3o,7o,7,,,, / t

Disemi- carbazone 222-223

Oisemi- carbazone 175 -176 Dioxime 167 -168

Conjugated Hydrogenolysis of 7"Furylalkanols. The initial ?/-furylalkanols- l-furylbutanol-3 and 1-furyl- pentanol-3, in amounts of 2000 g, were delivered to the skeletal Ni-A1 catalyst from an automatic burette with a space velocity of 0.1 h -1 at 240 ~ After separation from water and drying with calcium chloride, the catalyzates were distilled on a column with an efficiency of 40 theoretical plates. The fractions corresponding to the homologs of furan and tetrahydrofuran were subjected to hydrogenation on palladium-plated charcoal in the vapor phase at 150 ~ After distillation on the column, 2,5-dimethyl- , 2-methyl -5-e thyl - , and 2-methyl-5-n-propyltetrahydro- furans were isolated from the catalyzate of 1-furylbutanol-3 in a total yield of 65-70% while 2-methyl -5-e thyl - , 2,5-diethyl-, and 2-ethyl-g-n-propyhetrahydrofurans, the properties of which were published earlier by one of he authors [3], were isolated from the catalyzate of 1-furylpentanol-3 in the same yield.

The fractions with boiling points above 190 ~ (30~ contained mixtures of three ),-diketones: hexanedione-2,5, heptanedione-2,5, and octanedione-2,5 from (1-furylbutanol-3), and heptanedione-2,5, octanedione-3,6 and non- anedione-3,6 from (1-furylpentanol-3). The diketones were isolated in the pure form by fractionation on an effi- cient column under reduced pressure. Their yields and properties are cited in the table.

S U M M A R Y

lrFurylbutanol-3 and 1-furylpentanol-3 undergo conversions as the result of conjugated hydrogenolysis with hydrogenation in the vapor phase on skeletal Ni-A1 at 240~ former to hexanedione-2,5, heptanedione-2,5, and octanedione-2,5 in a total yield of 30%, the latter to heptanedione-2,5, octanedione-3,6 and nonanedione-3,6, in the same total yield.

L I T E R A T U R E C I T E D

1. I .F . Bel'skii and N. I. Shuikin, Dokl. AN SSSR 128, 945 (1959). 2. I .F . Bel'skii and R. A. Karakhanov, Izv. AN SSSR, Otd. Khim. N. 1962, 907. 3. I .F . Bel'skii, Izv. AN SSSR, Otd. Khim. N. 1962, 142. 4. N . I . Shuikin and I, F. Bel'skii, Dokl. AN SSSR, 131, 109 (1960). 5. N . I . Shuikin and I. F. Bel'skii, Dokl. AN SSSR 115, 330 (1957).

All abbreviations of periodicals in the above bibliography are letter-by-letter transliter-

ations of the abbreviations as given in the original Russian journal. Some or all of this peri-

odical literature may well be available in English translation. A complete list of the cover-to-

cover English translations appears at the back of this issue.

698