ETHOXYAND BUTOXY-ACETYLENE
Feb., 1942
Summary 1. CHorogenin has been converted to tigogenin without altering the C-3 hy&oxyl group. This proves that the C-3 hydroxyl has the 0configuration.
[CONTRIBUTION FROM
THE
223
2. epi-Chlorogenin has been prepared. 3. Chlorogenin and its epimer are analogous to other do-steroid carbinols epimeric a t C-3 in behavior toward digitonin and sodium amylate. STATECOLLEGE, PENNA. RECEIVED DECEMBER 26, 1941
CHEMICAL LABORATORIES OF THE UNIVERSITY OF CALIFORNIA AT Los ANGELES AND HARVARD UNIVERSITY ]
OF
Acetylenic Ethers. 11. Ethoxy- and Butoxy-acetylene BY THOMAS L. JACOBS, RICHARD CRAMER~ AND JOHN E. HANSON I n the first paper of this series,2 the synthesis and properties of phenoxyacetylene and substituted phenoxyacetylenes were described. It seemed likely that simple alkoxyacetylenes would show quite different properties. The following reactions have been employed to synthesize two such compounds
from saturated ethers and l-alkynese4 Chalmerss found that the molecular refractions of aliphatic vinyl ethers were also normal. While phenoxyacetylene gave a white silver salt which was sufficiently stable to permit analysis, the alkoxyacetylenes gave only black precipitates probably containing metallic silver. These burned Zn with a puff when dry,but showed no tendency to CHZBrCH(0R)z +CHBr2CH(OR)2-----+ explode. When the freshly precipitated derivaCzHbOH tive was treated with dilute nitric or sulfuric acid, KOH BrCH=CHOR dH-CEC-OR the odor of ethyl or butyl acetate was a t once apBromoalkoxyethylenes were prepared by the parent, and these esters could be isolated in low action of zinc and alcohol on dibromoacetals in yield. Ethoxyacetylene gave a white mercury the same way that alkenes are obtained from P- derivative which rapidly turned brown. While bromoether~.~When the starting material was no attempt has yet been made to synthesize such the dibutyl acetal, a mixed acetal of monobromo- substituted acetylenic ethers as RCECO-Alkyl acetaldehyde, BrCH2CH(OC2Hb)OC4H9, was ob- by the use of sodium or bromomagnesium derivatained as a by-product, apparently by the addi- tives of alkoxyacetylenes, ethoxyacetylene gave tion of a molecule of alcohol to bromobutoxy- one mole of methane in the Grignard “ m a ~ h i n e ” ~ ethylene. When a large run was attempted this and none of the reagent was used in other ways. mixed acetal was the principal product. No diAlthough ethoxy- and butoxy-acetylene polyethyl acetal was isolated in the preparation of merize much less rapidly than phenoxyacetylene, bromoethoxyethylene, where the reaction with they remained completely colorless only when zinc was more rapid. The elimination of hy- sealed in glass and stored a t minus eighty degrees. drogen bromide from the bromoalkoxyethylene by A yellow color developed in a few days a t zero distillation from powdered potassium hydroxide degrees or in a few hours a t room temperature. corresponds to the final step in the synthesis of When tubes containing the most carefully purified phenoxyacetylene. samples were opened a t room temperature a yellow Ethoxy- and butoxy-acetylene are colorless, color appeared in a few minutes. As in the case of mobile, evil-smelling liquids which must be dis- phenoxyacetylene, the moderately rapid heating tilled under reduced pressure. Their structures of a small sample in a sealed tube to around 100’ were proved by analysis, molecular weight deter- resulted in an explosion with the production of a minations and hydrogenation to the carresponding black solid. saturated ethers. The observed molecular refrac(4) Eisenlohr values of the atomic refractivities from Landolttions showed only slight exaltations as compared Bornstein, “Physikalische Tabellen,” 5th ed., Vol. 11, 985. The reconstant for the triple bond was used, ibid., Supp. Vol. IIIb, with the values calculated from constants derived vised 1696. (1) Present address, E. I. Du Pout de Nemours and Company, Wilmington, Delaware. (2) Jacobs, Cramer and Waiss, THISJOURNAL, 62, 1849 (1940). (3) Dykstra, Lewis and Boord, ibid., 62, 3401 (1930).
(5) Chalmers, Can. J . Research, 1, 464 (1932). (6) Slimmer, Bey., 36, 289 (1909). (7) Kohler, Stone and Fuson, THIS JOURNAL, 49, 3181 (1927): Kohler and Richtmyer, ibid., 52, 3736 (1930).
"4
RICHARD CRAMERAND JOHK E. HANSOW
~'HOMAR 1,. JACOBS,
Considerable interest attaches to the possibility of comparing more closely the carbon-carbou double and triple bonds in analogous, highly re
actix-e molecules. I t is well known that the presence of oxygen 011 a doubk bond increases its reactivity' and tile siiiie appeari to be true for the triple bond The rapid h j drolysis of viiiyi ethers in dilute acid wlutions has been followed quantitatively by a clilaronietric niethod.J At the same temperature (2e>')arid acid concentration (0.03AI) the hydrolysis of ethoxyacetylene to ethyl acetate was too rapid to measure. Butoxyacetylene was hydrolyzed rapidly by dilute acids and was coinpletely converted to butyl acetate arid polymer by refluxing ncath distilled water. The hydrolysis with distilled walcr at rooin temperature was slow. IithoxyacetJ-lei1e (lid not react with ethyl alcohol under simple refluxing, but at in the presence 01 the boron trlfluiJride-iriercuric oxide catalyst developed by Sieuwlaitd arid his co-worltersiOthe products were ethyl acetate and diethyl ether. Lndcr sinitlar coiiditions ethyl orthoacetate yielded the sa:rie products. The reactioii may therefore be formulated as the addition of alcohol to etliosyacetvlexic
CHsCOlC2Hs
T
(ClH,),O
The intermediate ketene diethylacetal" 1s known to add either water or alcoliol spontaneously with the evolution oi heat. ITith respect to these addition reactions the relative reactivity is IIiCzCHOCPI-I,
z-butyl bromide in boiling alcohol requires from three to four hours lor completion, while the corresponding reactions of sodium thiophenolate and sodium n-butyl mercaptide are. essentially complete i n a few seconds. 'There appears to be no previous quantitative m-ork on these reactions, although similar reactions have been extensively studied The reaction between methyl iodide and sodiun; ethylate was studied by Ilecht, Conracl aad BrLrIiner4 mho observed that the bimolecular rate constant is decreased by increasing iniiial c'once:~ trations of reactants. Seg:~llcr~~ made an extenrlc.r! study o€ the reactions of a scries t i f riciriiinl m J branched-chain alkyl iodides with late and observeil th? effects o f ten ( i ) T h e authors wish t o express their gratitude Reid, research consultant t o t h e d e r u r t m e n t . Fr problem and for his co,uti,uec? i n t e w - t i n t i z i 4 d n t tion. (3) Abstracted from it thesis sbl>r:iitted by G . I,.wl I i o y a ! ~til tli.: Graduate Faculty o f Emory C;niver,ity in partid fulfilllrirtrt rif t l l . requirements for t h e dcgree of .\faster of Science.
~ ~ i i t r a t i o raii d solvent on the bimolecular rate constants. The rate constants were found to decrease n ith increasing initial concentrations of reactants, ani1 no correlation was observed beLwccn rthactivity and dielectric constant of the 5 0 ! 3 ent It was concluded that the reactions are 'iiot icxic ' Ihe work of Hecht, Conrad and Hruchiier and that of Segaller on the reaction of propyl iodide with sodium phenolate was repeated by Schroeder and Acree6 as a test of their 'tliial hypothesis," according to which both ionic a i d iriolecular reactions proceed simultaneously aiic! i~idepcndentlv. The observed concentration explained by this hypothesis. Lauer 1 2 ~h a w receiitly studied the kinetics of 1 hc t-i licrification reaction of allyl bromide with iodiuiii phcnolatt with particular interest in conwiitrLiiion aiitl soli ent effects and conclude that ?hr redctioii i q entirely ionic. Concentration effect iy cyhincci a5 due to a \raving degree of solva' i o i i o f the phenolate ion. d>ject of this investigation was to deter>
L~(hroedcrand Acree, i h d , 106, 2682 (1914), and previoii,
