The Senecio alkaloids. Part 2: hydrogenation, hydrolysis and structural results of isatidine

Unde-rstepoorL Joui'IUt! uf ~·eter£nary Sf'lenn; and A._n·£mal ind-ustry, Tlolwne 14, Numbers 1 and:!, lunuary and A7;ril, 1940.

Printed i" the l'n ion of Sou tit Africa by the (;01-ernmcnt Printe1·. Pretoria.

The Senecio Alkaloids. Part 2 : Hydrogena- tion, Hydrolysis and Structural Results of lsatidine.

By H. L. DE \\' AA L. Seetion of Ph a rlll<lt·olog-y a n<l 'l'oxico I ng·y, () 11 derstepoort.

Lx the first Jl<lpt•r of this ~erie:; (de \Yaal, 193f.l) the isolation a11d ehen1ieal propt·rtie:; as ~~-ell a,; the results of thP preliminar~- hy<lroly:ii,;

:uul u£ t lte hydrog-enation of the alka l oi<l i ,;;1 tid i ne

,,- t:.

r<> recorrlt>d.

'l'hi;; alk;tloid is the aeti,·e prin .. iple particularly of Sr,tu'Cto isatideus hut 11·a,; abo fo11111l to lw pre,;ent in Yery mu<;h lilllHll<-•r cptantit-ies in S. retrorws ]).C. [t '""s then fuun1l that wl11•n isaticline was hydro- g-ellated ill tl1P pre::;eJI(·e of platinum dioxide four molt·<·ulp,; of hydrogen \\'ere cousumed, ,,-bich at the time •·ould not })(' p:-;pbinrd. Continuo11:; •·fl'ort:i lwn-• :iincr !eel to the n·pe<t!t·cl and f:1ciliL-Ltt·<l isol.1tion of th .. rrdutTd. I'OillpOIIIHl in thP crystalline fonn, :llltl thi,;

as \Yell <IS son It' ut hrr ,;( rudural rP:itllts on i:i;t! itline <ll'l' I ^Ill\\' n·portPtl upon.

T/,p .\'ot·utP of the 1/ydrnuenniPrl ,..;ulJstmu·l'.

'l'he hydi·og-eJiatioJI of i:;at-itline (PtOJ in half-nm·mnl or nol·mnl- hyclrochloric :1eicl ~olution !t·acls to the coi1S1ll11ption of four molt•t·ull·:i of hydrogen flll' one molec·u le of tlw alb loicl. The n•,mlti ng h~·dro­

g·enated prorlud has hPf'll i,;o]ate<l hnth <IS the free hasc and as its hydrochloride. Both are laeYo-rotator_,-, n_,-:i(a]JinP _-;ub:-;tance:; ant!

the :malysis l'Pvealed a sh-iking- phPnOlliPnon. l,;atidinr, (',RI-l0,,KO, took up

+

moler·ules of !t_,·clro"·en. thPn SJJiit. nff ont- mnlecnle of

\\'::tter, so th;tt·. thr T'1'S11lt-ing- h:ISP has the fnnnula. C18IL"O.,K or

(\ 8li3,00X.Il('] for it~ h~·tlror·lilnridt·, thus: C18H25N07

+

^4Tf2

[C1^sfl,~3^~07^{] -} H ₂0

(Cisi-I:lal\'07] ClsH31~0G-

0ct-ahydro-a ^:1 h Hlro-is;u-id inc.

I I .11d ro 1.'1-' Is o j Octu /, yd m-nn/1 .IJd t·o-iso 1/rl i ¹¹ e.

\\/hen or:tahydro-anhyuro--isatidine was hydrolysed ~~-it!t barium- hydroxide, the split in the moleeule occmTed at the same place as is the case "i th i sa tidine, i.e. a basic fission product containing- 8 carbo 11

433

THE SENECIO AL 1\ALOIDS.

atoms was prouuced, vill. C8H,03K, a tetrahydro-deri1·ative of isatinecine (C8H1"03::\"). Barger and his associates (1932) hyd1·o- genated retrorsine (as it,; diacetyl clerinttive) and found that only two molecules of hydrogen ,,·ere u,;ed. They failE>cl to isolate the hydrogenated substance but isolnted hom the h~·drolysis mixture a base C8H",O'N (retronecine has the formula C,H",02X), ,,-hich the)·

nnmed rehone('anol. Our base, C8H1,03:1, conhilmtes ne11· infonna- tion to,,·ards the chemistry of the SenE>cio alka loi<ls. a hy<l rogenated base having been obtained "·ithout any loss of oxygen atoms. Tlw hydrogen has therefor!:' saturatecl mo,;t likely ethylE>nic or hen11yleni(:

double bonds onl:'i-and the possi hili ty of an enol i <·-CO-CH2-g·ronpi n g-

~~;; sngo·ested for retrorsine must lw ruled out for is<~tidine. ·

The F1tnction of the O:vygen Atoms 1:n lsatinecine, Isatinecir Acid and Isotidine.

It must be accepted meanwhile that isatinecine C'sH,303N, has three reactive hydrogen atoms although this could not he acetyla.ted or cletermined (ZereiYitinoff), in the latter case 1lue to its insolubility in Pitlter pyridine or anisole.

Isatineeic acid c,OI-IlGOB, is a dihydroxy, diearboxylic acid and the function of all its six oxygen atoms is therefore kno"·n.

Isati<line, c,SH25NO,, •tceorcling to Blad:ie (1907) may haYe three r-eadiYe hydrogen atoms (i.e. hydroxyl-groups), aml the J·etttaining- four oxygen atoms must then be contained either in b\·o ester•

linknges or in one ester-linkage and one lactone g-roup.

Isatineeic acid so reaclily forms a monolactone (see experimental part), that the slightest deviation from the optimum conditions for the formation of the dibasic acid results in the isolation of the monobasic monolactonic acid. 'l'he eqmdion for the h~·(lrolysis of the alkaloid may therefore be either:

I. C1sH25N07

+

2 H20 =

isatidine

or

II. C18H25N07

+

^H20 isatidine

CsH1303N isatinccinc

C8H1303N isatinecine

+

^CJOH1606

if\atinecic acid or the 'new' acid (sec p. 445).

+

^C\oHH05

isa.tinecic monolactone.

HeYersely the alkaloid can therefore either be constituted by the ('ombination of the diba.sic acid, C,0H, .. 06 , with the base isatinecine, C8H,303N, by two ester-linkages, e.g·.

(

CsHloN ...

~ -

^OH

^*

1 - 0

l -

0

*

HO

-l

*

HO - ~C6^H6.

CO

-J

^{(CH3 ) 2}

co -

434

*

3 react. H. atoms.

H. L. DE WAAL.

Or the alkaloid may be a combination by one ester-linhng of isatinecine with the monolactonic acid as follows:-

r

⁰

-l

1 -

^OH

^* I

C,H,N ...

t ^~·

^OH

^* *

HO

^{oc -}

-

¹

^IC6H6. (CH3)2

^*

^{3 react. H. atoms.}

0 -

co _{- J}

C₁₈H₁₅N0₇ (isatidine)-sce equation II.

The Nat~t?'e of the Natural and Hyclro[Jenated lsatinecic Acids.

As is described. in the experimental part isatidine yields two different acids on hydrolysis, depending upon the method used. vVith alcoholic KOH a dibasic acid, U, 0H'"06 , with melting-point 181·0° C.':' and dextro-rotatory is obtained (see de \Vaal, 1939);

this acid as has now· been found also forms monobasic monohctonic acid. Using Ba(OH)2 for the hydrolysis an isomeric dihy<hoxy- dibasic acid. is obtained, \Yith melting-point 148 ·5° C. and either inactive or dextro-rotatory. Its corresponding monolactone has now also been isolated for the first time with an [a

J if

=

+

108 · 8(H20) and a melting-point of 197-8°C. In a private communication to the author, Dr. J. J. Blackie of Edinburgh suggested the name

" isatineeic acid" to the Ba(OH)2 hydrolysis acid of m.p. 148·5° C.

which ''"e now will retain iu future, and the KOH-hy<lroly;;is aeid of melting-point 181· 5° C. will meanwhile be termed the " ne\Y "

acid. until its identification ba.· been completed and a suitable name, if necessary, suggested.

Both " isatinecic " acid and the " new " acid as well as their monolactones (which incidentally prove that in each case one hydroxyl-group must be situated in the y-position to one carboxyl- group) can be very readily hydrogenated in the presence of Pt0₂^• In each case 2 molecules of hydrogen are consumed for one molecule of the acid. As these hyrlrogenatecl acids persist to be of a syrupy nature it is hoped that it will he possible to isolate ester-derivatives in a crystalline form.

No"· octahydro-anhydro-isatidi ne, C 18H31 06N, on hydrolysis yields a basic fraction C₈H170₃N, thus aceounting for t\YO moleeules or four atoms of hydrogen. Again, octahydro-anhyclro-isatidine sho\\-s a nett increase of six hydrogen atoms only and a loss of one oxygen atom (although 8 atoms of hydrogen had been taken up during the hydrogenation). Therefore the loss of two h~7drogen atoms and one oxygen atom as one molec~tle of 1cnter must ha1.:e occvrred in the acidic moiety of the hydrogenated suhstanre, C,8H3100N. I£ such an intramolecular elimination of one molecule of water ha<l taken place in the acidic fraction of the molecule, then it is expected that the hydrolysis of ocbhyclro-anhydro-isatidine ''"ill lead to the isolation of a C10H2000 dibasic acid which had lost one molecule of water, i.e. a C,0H180_, dibasic acirl. Should the hydrolysis lead to the isolation of a monolactonic acid, then similarly its formula will be C,0H₁₀04

(i.e. C₁₀H,₈0,-H₂0).

---

* .·\II melting-points are corrected (Kotler micro-melting-point apparatus).

21 4;:35

THE SENECIO ALI{ALOIDS.

It is also perfectly clear from the two part formulae for isatidine (see page 434) that the loss of one molecule of water in the acidific moiety of the hydogenated substance cannot be due to a lactone formation in that part of the molecule. It can only be accounted for by the reaction o£ one hydroxyl-group _with one ?t~er hyd1:ogen atom to eliminate one molecule o£ water m the aCidiC fract10n of the molecule.

It is hoped that this obscure problem will be clarified in our next contribution on the subject after the number of the reactive H atoms in octahydro-anhydro-isatidine has been determined and the hydrogenated acidic fraction has been isolated. Similarly it will be interesting to know whether the same phenomenon of water elimi- nation takes place during the hydrogenation of isatinecic acid itself as well as its monolactone.

ExPERIMENTAL PART.

Catalytic Hyd1·ogenat1:on and Red1tction af Isatidine and the I solation of OctahyJ:ro-anhydro-isatidine.

10 Gms. Isatidine dissolved in 70 c.c. N hydrochloric acid was hydrogenated under continuous mechanical shaking (Gattennann and ,Wieland, 193G) using 200 mgm. platinum-dioxide as catalyst.

'l'he hydrogen consumption advanced as follows:-

The first molecule of hydrogen was taken up after 100 minutes, i.e. at the Tate of 420 c:.c. Hz per hour.

The second moleeule of hyLhogen 11·as taken up a:Eter a further 110 minutes, i.e. 390 c.c. Hz per hour.

The third molecule o£ hydrogen was ta ke11 up after a furthe1·

145 minutes, i.e. at about 290 c.c. H2 per hour.

The fourth molecule of hydrogen was taken up after approxi- mately 250 minutes, i.e. at about 170 c.c. per hour.

Various independent hydrogenations with 3 gms., 12 gms. ann 20 gms. of isatidine and 100 mgm., 200 mgm. and 500 mgm.

platinum-dioxide respectiYely in w::tter, half-normal and normal h:vdrochloric a!'icl solutions all proved that the first two molecules of hydrogenation were absorbed at practically the same rate but that the consumption of the third molecule of hydrogen \Yas much slower, whereas the fourth molecule of hydrogen was consumed at a still more reduced rate.

'fhe hydrogenated acid solution (above) of 10 gms. of isatidine 11·as very unstable to\\·ards acid or soda-alkaline pennang::mate solu- tions and gave strong precipitates with Mayer's, Wagner's and Dragendorf's reagents and with phospho-tungstic acid. Thorough shakings of this acid solution with ether or with chloroform removed nothing. 'l'he solution was then alkalinified with concentrated ammonium hydroxide (1 : 3H₂0), allowed to evaporate and finally dried in a vacuous olesiccator over concentrated sulphuric acid. The residue was then extracted first with acetone (twice) and then with chloroform followed by absolute alcohol.

436

11. L. DE \\"AAJ ..

The acetone solutiorr deposited a good c:rop of crystals (about :2 gms.) ~wd the chlorofOl'm solution on cYaporation left about 5 gms.

of an oiJ_v substauce.

The pm·if-ied n yst;1];; (sec l<'ig. 1) from the ac:eloue solution \l·as dissohed in a little ahc:olute al(·olwl from which it c:rysblli~~,ed in cluste1'S of nec<lles on tl1e addition of a small Yolume of d rv ether.

l<'1·om thr oih· residue of tlw ('hloroform extract the s;~me :-;;Ihstan<·e was isola!ed ·,d.ter repe::llcd he:1bncnt

or

the oil with acetone. The

;t('etoue 11·ashing'S deposited !he s<~me l>ase as 11·;u-; isolated above.

This base exhibited a double mcliir1g point. lt melted nt 115 to 120°, J'<•solidified :llld final\.1· mcHt·<l to ^a l'll·ar :.;olution a! 181 ^(o 1 8-~⁰ (;_

HrG. 1.

Oc;ta-ilydro-n n ilyclro-isa tidi llC x 3-5.

,1/ lcro-onalys£s.

0 -:3-1-i mgm. : ll<)(j,) mgm_ C02; -1- ·] 10 mgm. IT ₂U. :{-\-1--1- mgm.: O·J0-1- c.c. ::'\ :1t .22·!">° C. an(l 7GG m.m.

C'alr-11lall'd for C18H"10r.::'\:

found:

C=GO--:l-i-i p<'r c:ent.; l-I=~)·i-1- per cent.; N =;l-92 per cent.

C=59-01 Jler ec11t.; l-I=8·73 prr ('Cilt.; N =;l-85 per cent.

(SP(' r·onfi rm:d ion of this fonnu b from tlH· :111:ilysis of its hyrlro- chloride, p. 439).

'1'\w subsbwce hall :1 hitler L1ste; it n~aclily rlissoh·e<l in waLL'r, llll'thanol arHl acclil' al'i<l: it 11·aq solul1le in ethanol an(l chloroform;

it was sparing-ly soluble in fl('e(one, ben;,ol an(l rth~-1-al'dnte and 437

THE SE::\EClO ,\Ll\ALOlDS.

"·a,; insoluble in ether and petroleum-ether. A .-;ulutiou of octahydro- anhydro-isatidine iu twice-normal hydrochloric acid gave strong precipitates with phospho-tungstic a<·id and with l\Iayer's, \Vag-ner':-;

and Dragendorf"s alkaloidal reagents.

The formula cl8H3,0GX wa.-; definitely established by the prepa- ration of the hydrochloride from this base and the isolation of the hychoc:hloride hom the hydrogenated acid solution.

J solation of Octah.ydro-a1111 ydro-isatid in e-hydroch lor ide. This <'Om pound ''"a" Yery n·<1cli 1~- obtained \dtPn isalicline "·as

<·uta Jyh cally reduced in <I normal hyclroehlorie acid solution (see aboYe) nn<l the filtrate nftpr !he hy<lrogenation allo"·ed lo eYaporate in front of a fnn at rdOJll t<'mpnatun'. C'n·stuls rapi<lly bcg·an to

;;eparutl' in the fontl of stout prismatic l"Olum11s. ThP liquid was finally CYaporated to <lryne~s on a "·;J(er-bath. The n yslals '"ere dried, washed with acetone follo"·ecl b.Y ether <UHl recrystallized from hailing- ethanol. After t"·o n'cr:ysblliY-ations tlw hychochlori<le (see .Fig. 2) meltecl sharply nt 218° ,,·ith strong eYolution of g-as to n

l"leflr melt. ·

Octa-1'-'·dro-an !J_,·d ro-isat tel i ne-hyd roch Iori de x 3,3_

Optical Rotation.

\\.ht ....... .

\'ol ... . 8 .. ... .

50·0 mgm.

7 · 5 c.c. H₂0.

- 0·35.

- 0·3.') X 7·5 X 1,000 1 X 50

438

. II ino-uuulys1s:

5·107 mgm.: 10·875 mgm. C0₂^: 3·870 mgm. H₂0.

2 · 914 mgm. : 0 ·090 c.c. N at 23°C and 766 nun. Hg.

13·420 mgm.: 4·940 mgm. AgGI.

H. J,. DE WAAL .

Calculated for C₁₈H₃₁0₆ N.HCl C.

=

54· 88 per cent. : H = 8 · l 9 per cent.

N = 3 ·55 per cent. : Cl = 9 ·00 per cent.

Found.. .. . .. .. .. .. . .. .. . .. .. C. = 54· 87 per cent. : I-I = 8 · Ol per cent.

N. = 3 ·59 per cent. : Cl = 9 ·10 per cent.

Therefore. . . C₁₈H₃₁0₆N.NC1.

The substance was readily soluble in 11·ater, methanol and acetic acid; it was sparingly soluble in ethanol, ethyl-acetate and chloroform and it was insoluble in ether, acetone and petroleum ether.

PrezJamtion of OctahydTo-anhydro-isatidine (free base) j?·om the above hydrochloride.

'l'he pure hydrochloride (m.p.218°) was dissolved in a small volume of water and the solution made alkaline with a concentrated ammonium hydrate solution (1:3 H20). It "·as then allowed to evaporate in front of a fan. The residue, which had the consistency of a syrup, was stirred with dry acetone when it became crystalline.

Purification was effected by recrystallization from ethanol on the addition of a small volume of pure ether. The base had the same double melting-point and showed no depression when mixed with the free base directly isolated from the isatidine-hydrogenated solution (see page 43G).

Hydrolysis of Octahydro-anhyd1·o-isatidine and the 1 solation of Tetrahydro-isatinecine.

'l'he hydrolysis of Octahydro-anhydro-isatidine can be effected in t\VO ways: (1) immediately after the hydrogenation (Pt02 ) of isaticline was completed, i.e., with the base still in normal hydro- chloric acid solution, or (2) with the crystalline hydrochloride after its isolation. In the first case the filtrate, after 4 molecules of H2

had been taken up by the isatidine in N-HCl solution, was shaken with ether. 'fhe ether was removed and the acid solution neutralized with concentrated ammonium hydrate (1: 3 H20) and then 1· 2 mol.

of solicl barium hydrate were added. In the second casf' the (·rystalline tetrahydro-anhyc1ro-isatic1ine hydrochloride was dissolved in a small volume of water and a small excess of barium oxide-hydrate \Yas then added.

The solution (in either rase)with the barium hydrate was then re:fluxed for about one hour [e.g., 10 gms. octahydro-anhydro- isatidine and12 gms. of Ba(OH)2·8H20]. It was then filtered. The filtrate was titrated with concentrated sulphuric acid (l :4 H20) until just acid to phenolphthalein. The BaSO,, was centrifuged off. The clear supernatant was allo'll·ed to evaporate on a ·waterbath to dryness and the dry residue extracted with hot absolute alcohol. The alcoholic solution was then allowed to evaporate on a waterbath and the syrupy residue stirred with dry acetone. The base crystallized.

439

THE SEKECIO ALrUJ,OlllS.

'l'his substance was then Tepeatedly refluxed with acetone which removed the base and on the concentration of the acetone and the additioli of a small volume of e( her readily crystallized (see Fig. 3).

After one or two similar recryRtalliza tions this base tetrahydro- isatinecine, had a constant melting-point (sharp) of 174·5°. It is ve1-y hygroscopic.

FrG. 3.

Tehnh.Ydro-isatinc<.;ine, ^Jll.p. 175xl0.

Micro-analysis:

5·201 mgm.: 10·380 mgm.C02; 4·440 mgm. H₂0.

3·021 mgm.: 0·210 c.c.N at 25·5° C. and 754 m.m. Hg·.

Calculated for C8H1703N :

C=54·83 per cent.; H=9·78 per cent.; N =7·99 per cent.

found:

C=54·43 per cent.; H=9·55 per cent.; N =7·90 per cent.

Optical 1·otation .

The mean value of a solution of 50· 0 mgm. in 8 · 0 c.c. distilled H20 was found to be as follows : -

a= - 0·55°.

Therefore [ a

J ^~O

^{= - 88·0°.}

Chemical Properties :

This substance (tetrahydro-isatinecine) was easily soluble in cold water, ethanol, methanol and chloroform.

It readily dissolved in hot acetone; it was sparingly .solul,le jn ethyl-acetate and practically insoluble in ether and petroleum-ethel. A solution of tetrahydro-isahnecine in t\vo normal HCl gave strong· precipitates with phosphotungstic acid and with Wagner's,

-+4 ()

H. L. DE II".AAL.

Dragendori's and .Mayer's reagents. With :Mayer's reagent lemon- yellow crystalline flakes were obtained with a cruue melting-pomt o:£ 117°. 'l'etrabydro-isatinecine was unstable towards soda-alkaline potassium-pennanga.nate solution.

Bm·ium,-hydroo?:ide hydrolosis of Lsatidine. '' The 1·solation of ... isatinecine, isatinecic acid and isatinecic monolactonic acid.

To a solution of 20 gms. of isatidine in 200 c.c. of water was added 20 gms. of solid barium-oxide-hydrate (1·2 mol.) and was then refl.uxed for 40 minutes. 'l'he filtrate "·as titrated with concentrated sulphuric acid (1:4 H20) until just :1cid to phenolphthalein and the BaS0₄ precipitate centrifuged off. 'l'he supernatant was decanted and evaporated on a water bath under reduced pressure. The dry residue "·as then twice extracted with hot ethanol which readily removed the base isatinecine.

On concentration of the alcohol and the addition of acetone isatinecine crystallized out in a very good yield of about 8 gms.

Thus recrystallized the basic fission product (see Fig. 4) decomposed at 212-215°.

FIG. 4.

lsatinecine, m.p. 212-5°, XlO .

. 11 i c1·o-auolysis.

4 · 729 mgn1. dried at room temperature in high vacuum over P ₂0₅ lost 0 · 058 mgm. in weight.

(a) 4 · 671 mgm.: 9 · 655 mgm. C02 ; 3 ·160 mgm. H20.

• Ln a private communi<:ation Dr. J. J. Blnckie of Edinburgh suggested the

ilydroi~·,is 11·ith Ba(OH), for which 1re w1sh to express our si.ncere thanks . ..J.-1 L

THE SENECIO ALI{AJ,OIDS.

(b) 2·865 mgm.: 0·214 c.c. N at 25° C. and 764 m.m. Hg. found: C=56·41 per cent.; H=7·57 per cent.; N=8·6 per cent.

Calculated for C₈H,₃03N: C=56·12 per cent.; H=7·65 per cent.; N = 8 · 2 per cent.

(c) Active hydrogen could not be determined due to the insolu- bility of the substance in either pyridine or anisole.

(d) Negative for C-methy l groups.

(e) Negative for N-methyl groups.

Optical Rotation.

[a]

^{2DO = +22·4°} (50·0 mgm. w 8 c.e. H20J

Properties.

h ::rtinecine gave :;hong precipitates with phosphotungstic acid, Wagner's and Dragenrlorf's reagents, but nil "·ith Mayer's reagent.

It iR soluble in water, methanol, ethanol and acetic acid.

It is sparingly soluble in acetone and ethyl-acetone mul practi- cally insoluble i11 ether, petroleum-ether and chloroform.

isolation of I satinecic Acid and lscd1:necic M onolacton-ic Acid.

The residue after the extraction of the base with ethanol (above) was then dissolverl in a small volume of \Yater, titrated with concen- trated sulphuric acid (1 : 4H20) until the solution was this time just acid to congo red. The BaSO,, was again centrifuged off :mel the SUJlernatant evaporated to dryness as already stated for the base above. The dry resiclue "·as thE'n refluxed with ethyl-acetate fm two to three minutes which removed the acid, the ethyl-acetate solution was dried over exsic(:ated N a2SO_, and if necessary decolourised by the addition of a pinch of charcoal. On the addition o£ a little petro·

leum-ether to the filtrate isatinecic acid crystallized in needles. After a similar recrystallization the acid crystallized in fairly large beautiful colourless needles (see Fig. 5) with a clear constant melting- point of 148 ·5°.

When similar hydrolysis experiments of isatidine "·ith barium- hydroxide were carried out under slightly excessive heat, the hyclro- lysis invariably resulted in the isolation of the isatinecic monobctonic acid. This monolactonic monobasic acid readil.v crystallizes into beautiful brge crystals (see Fig. 6) from pure ethyl-acetate only. After the third recrystallization the substance was pure with a sharp melting-point at 197-8° C.

442

THE S:ENECIO ALfi:ALOJJlS.

iVIicro-analys1:s of Isatinecic Acid.

(a) l'he inactive acid and (b) the active acid. [ a _] ²⁰ D =

+

8G(H20) (a) 4·260 mgm.: 8·100 mgm. C0₂; 2·640 mgm. H₂0.

(b) 5·47{) mgm.: 10·410 mgm. C02 ; 3·410 mgm. H₂0.

found (a) : C =51· 88 per cent. ; H = 6 · 94 per cent.

found (b): C=51·87 per cent.; H= 6·97 per cent.

Ualculated for C,₀H,₆0₆: C=Gl ·72 per cent.; H=6·94 per cent.

(c) 0·20lmgm.in3·027mgm. camphor; 6 =11·2°. therefore mol. weight= 238.

cl O H, "o"

= 232 · 23.

(d) Active ll Deter1winat1:on (ZerettFitinoff).

(1) 6·210 mgm.: Vo=l-23 c.c. CH.,.

(2) G·301 mgm.: Vo= l ·25 c.c. CH.,.

found (1)=0·88 per cent. reactive H atoms.

found (2) = 0 · 88 per cent. reactive H atoms.

Calculated= 0 · 8G per cent. for bnJ reactive H atoms.

therefore2 - OH groups. (e) Micro-titration.

fJ4·0 mgm. of the dibasic acid dissolved m about 5 c.c. H20 required 4 · 60 e.c. N N aOH.

Now 23·2 mgm. (mol.wht.232) required 2·0 c.c.

N N aOH for 2-COOH.

Therefore 54 mgm. requirfld 4 · GG c.c. N aOH for 2- COOH.

'rherefore 2 carbo:s:yl-group:;.

K o lactonic groups were found to be present.

(j) Solubility.

Tsatinecic acid immediately dissolved in eold water, cold 1uethanol, cold ethanol, cold acetone and cold acetic acid. It was soluble in ethyl-acetate and practically insoluble in ether, petroleum-ether and chloroform.

Chemical Properties of lsatinec£c !lfonolactonic Acid.

l. Micm-analysis.

5 · 311 mgm.: 10 · 945 mgm. C02 ; 3 ·142 mgm. H20. found : C =~ GG · 22 per cent. ; H = G · 63 per cent.

Calculatecl for C,0H,40,: C=5Ei·08 per cent.: H= 6·59 per cent.

444

H. L. DE ""AAL.

(2) .1/ lcro-t/tuttion.

50·0 mgm. acid cl.issohecl in about 5 e.c. H20. required 2·30 c.l:. ~ NaOH.

:Xow 21·4 mgm. (mol.wht.214) required 1·0 c.c. N NaOH for 1-COOH.

Therefore 50·0 mgm. required 2·32 c.l:. NaOH for 1- COOH.

Therefore one carboxyl group.

(3) So7;onificat1:on.

(4)

-± r:.c. ~ :XaOH was added to the titrated solution (:G), and this solution then refluxed for 30 minutes.

Back titr:1tion required 1·85 c.c. ~ HCl.

'l'herefore difference=2·15 c.c. ~ NaOH.

Therefore monobasic-mon olactonic-acid.

'l'hPory for one lactone-group=2·32 NaOH.

Specific Rotation (mean of several determinations). Weight=50·0 mgm.

Volume=8·0 c.c. H20 U= +0·68°

+

^{0 · 68 X 1000 X 8}

1 X 50

= +108·8°.

(5) Sol'Ub1lity.

The isatinecil: monobctonic ar·id dissolved in cold water, cold methanol, cold ethanol and cold acetone, but not so readily as the clihyclroxy-dibasic isati11ecic acid. It dissolved in ethyl-acetate and acetic acid, but was practically insoluble

1n ether, petroleum-ether and chloroform.

Alcohohc KOH Hydroly:sls of lsatid,inP.

The lsolat'ion of the " lVew" Isomeric Acid, C10H1.,0.,. In the first paper of this series (de vVaal, 1939), the hydrolysis of isatidine with alcoholic potassium hydroxide had been recorded and the isolation of the arid fission product only had been descriher1.

The following improved hydrolysis led to the isolation of both the base and the acid.

To 10 gms. of isatidine clissohed in 80 c.c. ethanol was added 4 g-ms. of solid KOH (=1·~~ mol.) antl then boiled unrler a refiu:x condenser. (The addition at this stage in another experiment d 2 c.c. of "·ater ler1 to the same h.vtlrolyRis results.) vVithin G minutes crystals separated and after 10 minutes the contents of the flask was one mass of crystals. The hydrolysis was stopperl and the crystals

44f)

TI-lE SEC\ECJO ALl\.\ LOJ I >S.

were filtered oft, tlwroughly 11.:1:-;hetl IYi! II ethanol and dried. Til io;

~ubstanee ~~-a~ tiiP dil:nsic· potasoium ,.;alt of the inar-tin• aeid.

I

Front the alcoltolie filtrate:• i~atinecine 11as isol:tlecl adopting the santee proct>clure as dPSnilwcl ±nrtlwr a bon• for tlw B:1(CJII )" hydroly~is.]

Lsolutw11 of tlte • ..J.cul.

The ]JOtassi um n ysblline salt 11·as clis-;oln·d in a Lout :l(J c .c. u1 cold water nncl the wluiion tli1iclecl into [11·o Pllual portions. 'l'h<>

one por·hon \\·:1s neutr:tlizecl 11·ith t·onr-entr:ltecl sulphuric acid (I :4U20) until just ncid to eong-o red allll tht· other portion neuh:tlized \Yith c·onc·Ptltrated hythoddorit· ac-id (l:J H}J) ag-ain until ju-;t :H·icl to Cong-o 1·ed. ('L'llP oh.ic·d 11·:1s io test 11·ltptJter H2^~0, 11cruld lc::id to tit8 iwl:!tion of a clihasi<· :tcicl :lttd liT! to the i:iOiat ion of a munohnsic monol:tctonic acid.) From both filtrates on evaporatiu•1 c;ryst:tL; separated. The nYst:dliz:ttton 11·a:; ttwn: rapi<l anll contplete hum the H2SO, n8ut1alizecl ~olution. Jn both in:;b ttCl'S Ollt' and the sa tile clib:1sic acid c;r_ystn llized, identical 11·ith tlw clib:1;;ic· ar-id n l ready clc!scribed in the fir6t publit·ation (19:39). \\ith ~>Oli<l KOJl the iwlaiccl acid 11·as found to 1H' inacti,·e, 11·bereas fornwrly 11 iih t \\'It"<' normal alcoholic- potassium ltyclroxidP the opt icnlly :1diYe <lihasic·. acid ,,·as isola ted. 'l'lte melting of this a c:icl is lSl · ^fJ0 <:01TPd8cl ( nol 118-l 80° <IS ~~-<IS repode<l prcyiously).

Sr.IDL\1(\'.

J. The prinl'iple alk,1loicl of ,'-'enecio isotuleu., D.C. isatidit:c,

C,8^H~)'\07^, Olt h_,·drogenatiott in the presenc-e of platimun-dioxiclc·, took up S atoms of ltyrlrogen \Yith thP elilllinaiimt of <JllP molet:ltle of 1v:liPr. 'l'he fonnula is C,,H,,O"::'\, m.p. lS:l-18-!⁰ C'.

·> The hychog-Pnaterl cr.1·stallint> suh6Lutc-e, odnhyclro-aHhydTo-

isaticline, rpacli],· forms a h~·clrocltlorille ^111.p. 2L')° C., [a] i? ~ -fJ2 · '>(H"O), :1111l can easily he t·onH rte<l into thP free hase.

:;. Od :dtydro-:tJlhydro-isatidine or its hyclrodtloride _yields 011

hyclrol.v;;is IYith Jl:.(OH)" :1 Jll'll. basic· fission prodnd 11·it h the> formub CsH170_,N. lsatinecine has the fonnuln (\ IT",O,K. It ^lS thPrPfore a tc>hahy<lro-isat inPcine.

4. Tc-dTahvclro-is:ltiJtPf'ittt'. 111.p. 17~>⁰ ('. :1nd [a];~' = - 8W·'; 1~ unstable hn1·:ntlR pot:L'siunt-]ll'l'lllang·:ln:d<· :ntcl giYPS posihvP reactions with alk:doicl:ll l'P:l.!.!'Pilts.

:J. h:d·icline hydrolysed 11ith B:1(0HL ~·ields isatinecinc~ allll the diltldrox\·-rlihnsic i . ..;ahnf'c·ic ac-icl fornnd:1e C,H,_,Cl,X ancl (',.,1-f"Jl, l'P.'iJ;edi

Y ;'

J_v.

(i. \rVhen iB:tii<line i.~ ln·drol1·secl 11·it·h alcoholic: KOH the ;;ante h:1s8 isaiineci ne, ln1t a diff~Teni. dihasic nr·i<l is ohtainerl, isomPric·

with isatineeic acid. It has m.p. 181:5° C.

7. Is:ltinPcic· acicl n•:lflil_,. forms n tnonobasic· monolndonic aeid,

C",H"O" n1.p. Hll-8° nncl [a]i? ~+lOS 8° (H,O).

8. Both isati nec·ic· acid nncl iL " new " isomeri<: acid Paeh take up four :1 imns of h_nltog<'n on h~·rlrogenn t ion in the presence of PtO".

44G

H. J,. DE W.·LIJ..

\). Fron1 tl1e hydrolysis results 11·ith odali;ydro-anhydro-isatidine and the isolation of the basic fission proclu<.:t telrahydro-isatinec1ne, C,H, 0₃::'1, it is eonduclecl, thnt it must ill' the ac;idie had ion of the hydrogenated ll!oJeC"uJe \Yhich eliminates OJIC' moleeule of 11·atl'r <I~

follows:-

(', ,.'! 111;0" + 4FI2 = C\oH 200.,. c,,Ir".,(\ - H"O=

c,on ,s o,.

c.LI , 03::'1 C,oH,s05 = C,sH:Il(JU +

:n r"o.

LO. 'l'he work is being rontinuecl IYith the Yie11· to furnish u fudhl'l' cuntribulion lu11·:nd,; tlH· ,;lrul'iure of thr ~E'IIl'cio alkaloill.'.

'l'he mic·ro-:tn<ilyses (C- H, ::\, Cl, adi,·c· H, N- CII_{3 ,} C-CH_{3 )}

" ''IT t·:nried onL 0.1· IJ1· . .c\... ::-ll'l10eller, llerliu, <JlJ(l Dr. K. \Vallenfels, Jleidc•lherg. Gennany. The photographs 11·ere taken h,v }Jr. '1'. ~Ieyer.

()nderstc·poort. I 11'01lldlike to tlw11k till'se gentlenJE'Il since1·ely for their a. si . .;bnl'e.

A UTHOJ~ . s ::; ()'l'J;.

After this article had bern wbmittNl tu the l'ress it IYas dis- c·overed thnt isatineC"ir arid 1s a per acid, 1.e., has one

- H..CO.O.OH gToup and tl1at this is e;;lcr-JinkPd in i;;atidine.

'l'herefm·e both isahdinr ancl isatinpcil· acid h:J,·e Pach Ollt' pl'r-oxygrn

alom. accounting ·for oJJe excess h~·drop:eJJ molecule during thPir

hydrogen:Jtions above those required for the saturation of olefine clouble-honcls. (A more clrtailrcl artil·le 11·ill appear in :1 F;ubseqtH'nt is;:;ue of this jomnal.)

LITimATCHE.

HAHUIW, G .. SI•:SHADill. '1'. R .. WAT'I', II. 1•; .. Al'\n YABUTA. T. (U):l!i).

Alkaloids of SPllE'!'iO. Part .,. nctrorsinr' . .T. ^('//('Ill. Soc .. P:nt ]. pp. ll-lli.

BL . .\CKJE. J. J. (1037). Th<• alkaloids of th<• G<'nus Senec·io. Phr,·;ll . .Til/., pp. l-8.

JH; \VA A I,, H. 1.. (1 0:30). Tbe Senecio alkaloids. Part 1. The Isolation of Isati- dine fro1n 8. l'r'f,.,o·sus nnd S. isofir/PJIS. Ondel'sfP . .fill. Fet. 81'i. olld A11.

l nd .. Vol. ·12. No. ] . pp. 1:)!5-lG::J.