the synthetic use of metals in organic chemistry

THE student of Organic Chemistry will probably be impressed at an early stage with the importance of metallic sodium and its compounds in syntheticwork, and will subsequently mark the va

IN CHicariaTRy AT THK crrY AND aviu)H TKOiiwroA.L

COLLKGK, l^INHBUltY, LONDON

LONDON

J & A C H U R C H I L L

7, aREA.T MARLBOKOUO-H STEEET

l-0 5V

LIBRARY

THE student of Organic Chemistry will probably

be impressed at an early stage with the importance

of metallic sodium and its compounds in syntheticwork, and will subsequently mark the value of suchsubstances as acetoacetic-, malonic-, and cyanacetic-ester and their sodium compounds

He will notice the use of aluminium chloride inthe preparation of various aromatic compounds, willhear the story of the discovery of the zinc alkyls,and will possibly be attracted by those interestingbodies, the organo-rnetals

Various metals arid metallic, derivatives have beenutilised in the development of Organic Chemistry,and during recent years, much attention has beengiven to the use of magnesium in the Grrignardreaction and to the value of the carbides in thefixation of atmospheric nitrogen, while the reductionand synthesis of organic compounds in tlio presence

of reduced nickel and other metals has, by ment, led to the discovery of numerous catalyticchanges in the presence of certain metallic oxides

develop-VI PREFACE

In this volume an attempt has been made topresent an account of the uses to which the metalsand certain of their compounds have Tbeen put, andthe work is based upon a course of lectures, on thissubject, recently given by the author to the advancedstudents of Finsbury Technical College

Each chapter is supplemented by an appendix ofpractical work exemplifying the methods mentioned

in the text

Most of the preparations have been carried out inthe College laboratories, and in connection with fthispart of the work the author desires to acknowledgethe valuable assistance of two advanced students,Messrs T McLachlan and E Mendoza He is alsoindebted to Mr F W Streatfeild, F.LC., SeniorDemonstrator, for help during the reading of theproofs

A J H

LONDON;

February, 1914.

CHAPTER I.

SODIUM AND POTASSIUM.

Synthetic Use of t h e Metals—Sodium ethylate—Sodamide

—Sodium hydroxide—Potassium cyanide—Potassium

"bisulphate—Potassium hydroxide —Potassium n i t r a t e

—Potassium and sodium disulphates 1

C H A P T E R I I

COPPER AND SILVHXt.

Use of the Metals—Copper acetylene derivatives—Silver cyanide—Silver hydroxide 35

CHAPTER III.

MAG-NESIUM, CALCIUM AND BARIUM.

Applications of the Grignard reagent—Carbides of Calcium and Barium—Nitrogen fixation—Calcium and Mag- nesium nitrides—Hydroxides of the metals 42

CHAPTER IV.

ZINO AND MERCURY.

Metallic Zinc—Zinc chloride—Mercuric oxide—Metallic

mercury ^

Vanadium pentoxidc 11

CHAPTER VI.

IRON, NICKEL AND PLATINUM.

Ferrous sulphate—Ferrous potassium oxalate—Iron and ferric chloride—Reduction by reduced iron, nickel or cobalt 88

APPENDIX I.

PRACTICAL WORK: SODIUM—POTASSIUM.

Ethyl benzene—Anisole—Benzoic lene—Trimethylene dicarboxylic acid—Chlorof ormic ester—Carbonyl chloride—• Ethyl benzoate—Toluic ethyl ester—Aeetoacetic ester—Ethyl acetoacotic ethyl ester

anhydride—Hexamethy-—Aceto-succinic ester—Malonic ester—Ethyl malonic ester—Diaceto-succinic ester—Ethane tetra-carboxylic ester — Acetyl-acetoacetic ester—Antipy rine—Methyl succinic ester—Succino-succinic ester—Tin tetraphenyl

—Lead tetraphenyl—Mercury diphenyl—Silicon phenyl—Oxalyl-acetic ester—Hydroxy-methylene cam- phor—Acetyl-acetophenone—Ethyl acetophenone—Fur- furol acrolein—Cinnamyl-vinyl-methyl ketone—Acetic anhydride — Benzoin — Desyl-acetophenone — Phonan- throxylene-acetoacetic ester 104

APPENDIX IV.

PRACTICAL WORK : ZINC—MERCURY.

Citric acid—Use of Zinc alkyl quinoline—ITuorescein—Malachite green—Acridine— a-Methyl-indole—Propyl chloride—a-Ethoxy-quinoline

iodide—Naphthalene—Iso-—Phthalic acid 144

APPENDIX V.

PRACTICAL W O R K : A L U M I N I U M — T I N — L E A D

Dimethyl-aniline-phosphor-chloride — jp-Tolxiic-aldehyde — Diphenyl-methane—a-Hydrindone—Triphenyl-methane

—Acetophenone—o-Benzoyl-benzoic none — Hydrolysis of anisole—Toluene—Diphenyl— Oxalic acid 153

ABBREVIATIONS USED IN THE

J Am Chem Soc ~

J Soc Chem Ind =

Zeit ang-ew Chem =

Zeit phys Chem »

Liebig*s Annalen der Chemie.

Annales de Chimie et de Physique Berichte der deutsohen chemischen G-esellschaft.

Bulletin de la Soci6t6 chimique de Paris Chemisches Centralblatt.

Journal fur praktische Chemie.

Monatshefte fur Chemie.

Philosophical Transactions.

Proceedings of the Chemical Sooiety Recueil des travaux chimiques des Payw- Bas.

Transactions of the Chemical Society Zeitschrift fur angewandte Chemie Zeitschrift fur physikalische Cheniie.

THE SYNTHETIC USE OF METALS

IN ORGANIC CHEMISTRY

CHAPTER* I

SODIUM AND POTASSIUM

ALMOST the first metal to Tbe used for organicsynthesis, sodium continues to hold a foremost posi-tion among all the metals utilised as synthetic agents

in organic chemistry Although potassium was thefirst used, being applied by Frankland and Kolbe

in 1848 to the preparation of hydrocarbons by ing the metal with alkyl nitriles^ yet sodium hasalways received a far wider application Twenty-three parts by weight of sodium suffice to bringabout a chemical change which would require thouse of thirty-nine parts of potassium^ and thin fact,together with the lower price of sodium, gives thometal an economic advantage

heat-Another reason for the priority of tins metal is that

in many cases the more electro-positive and morochemically active potassium proves to be too violent

in its action, and renders the control of the reactiondifficult.

After the investigation of Frankland and Kolbementioned above, Frankland in the following yearheated metallic zinc with alkyl iodides, and besidespreparing paraffin hydrocarbons in this way, healso discovered the zinc alkyl s, the first of theorgano-metallic compounds.1

In 1850, Williamson prepared certain ethers by

the interaction of alkyl iodides and sodium ethoxide,

a method of preparation which rendered evident theconstitution of these bodies :

C 2 H 5 I + C 2 H 6 O]Sra = ]STaI + C 2 H 5 O.C 2 H 5

In 1855, Wurtz emphasised the importance ofsodium for preparing the paraffin hydrocarbons, andprepared di-isobutyl, by the action of the metalupon isobutyl iodide3:

2(CH a ) 2 CH.CH 2 I + 2Na - (CH 3 ) 2 CH.CHo.CH 2 CH(CH 3 ) 3 + 2NaI.

A few years later, Fittig applied this reaction tothe synthesis of aromatic hydrocarbons by condensingaryl and alkyl radicles The following reactionswill indicate the usefulness of this method8 :

C 6 H 6 Br + CH 3 Br + 2Na = C 6 H B *CH 3 + 2NaBr Brombenzene Methyl Methyl benzene

After 1850, various compounds were prepared by

SODIUM AND POTARBIUM 3

the agency of sodium and potassium, and tin* ing are examples of some of the bent known reactioiiH

follow-of this class:

Phenol and other formation :

CflHftONn + Oir,I « (yr fi O.0H 3 + Nal Sodium phonate, AtitHolo

(methyl phonyl othor).

The samo exchango is offoctod by lining an alkylsulphate or an alkyl liydrogon nulphato :

CaH 4 OK + O a ir B nS0 4 - CaUft.O.O.jlT, + KHHO, Ethyl hydrogon

sulphate.

2C 2 II 5 OK + (Cir8),so4 « 2cyr&.o.air3 + Kaso4

Methyl Htilphato Ethyl mothyl othor.

The following aro chai*actoriHtic roacjtionn ofalkyl potassium sulphates:

When hoatod alone tht^y yield OI

Cari6KSO4 « iUU

When boiled with water tjuvy yit^ld alcohols:

O a II ft KS() 4 •»• II a O ' cyiftOH -i- KUBO 4

When treated with KI, KCJN, K2H, KHH, thisy

yield alkyl iodidos, nitriloH, thio-others and captans respectively:

mor-RKSO 4 + icr ^ m + Kaso4

RKHO4 + KXIN * IU1N i K S() 4

2KKS<) 4 + IC,8 ™ K.H.R + ak 3 HO 4

KKBO 4 + KSII « K.H.II + K 9 H() 4

When heated with the alkali salfcH of organic ncidH,esters are obtained ;

RKSO 4 + OH 8 OO()K s Cir s COOR + K.HO,

KKSO 4 + OflllflCOO^a - € fl ir *

Sodium bonzoato.

4 SYNTHETIC USB OF METALS

Acid anhydrides are produced by distilling amixture of the acid chloride with an alkali salt ofthe acid :

CH 3 COC1 + CH 3 COONa = (CH 3 CO)X> + NaCl Acetyl chloride Acetic anhydride.

C 6 H 5 COC1 + C 6 H 5 COOK - (C C H 5 CO) 2 O + KC1 Benzoyl chloride Benzoic anhydride.

Numerous hydrocarbons can be prepared by theaction of sodium upon halogen substitution products

In addition to those already mentioned, saturated hydrocarbons can.be synthesised in thisway:

un-2CH 2 : CH.CH 2 I + 2Na « C H 2 : CH.CH 2 CH 2 CH: CH 2 + 2NaI Allyl iodide Diallyl.

2CH 2 : CHBr + 2Na = C H - : CH.CH: OIL + 2NaBr Vinyl bromide Divinyl.

Sodium has played an important role in the

pre-paration of many polymethylene hydrocarbons andtheir derivatives

The first member of this series of hydrocarbonswas prepared by Freund (1882), by allowing sodium

to act upon trimethylene bromide4 :

SODIUM AND POTASSIUM 0

Triinetliylene dicarboxylic oatoir.

The condensation product when hydrolysod givonthe corresponding acid and the latter on heating,passes to a monocarboxyl compound :

CHo\ yCOOH Heat CPL>\

| " N C X -> | " N CH.CO0H -i- COo.

C H 2 / \COOH C I L /

Similar compounds are formed by using lene dibromide and pentamethyleiio dibromido.0Numerous acids may bo prepared by tlio action ofcarbon dioxido upon aromatic halogen compounds, inthe presence of sodium

triinothy-This method was first used by Kekule iu 186(3 forpreparing benzoic and toluic acids from brombonzouoand bromtoluene:

CoHfiBr + CO 3 + 2Na == C (5 H ft COONa + NaBr

U S E S OF ACETO-ACETIC E S T E B

This useful r e a g e n t was discovered b y G-euther in

1863, who pi*epared i t b y t h e action of sodium upon ethyl acetate.

About t h e same time F r a n k l a n d a n d D u p p a , u s i n g

t h e same reaction, discovered t h a t t h e h y d r o g e n atoms of t h e r a e t h y l e n e g r o u p a r e replaceable b y sodium and various organic radicles.

G-euther r e p r e s e n t e d t h e s u b s t a n c e as O H 3 C ( O H ) : CH.COOC 2 H 6 , t h a t is /3-hydroxycrotonic ester, b u t

F r a n k l a n d a n d D u p p a p r e f e r r e d t h e k e t o formula OHg.CO.OHg.OOOOgHg, a n d r e p r e s e n t e d it as a c e t o - acetic ester 7

The formation of t h e substance m a y b e r e p r e s e n t e d

t h u s :

CH 3 COOC 2 H 5 + CH 3 COOC 2 H 5 = CH 3 CO.CH 2 COOC 3 H 6 + OftOH.a Wislicenus h a d b y 1877, i n v e s t i g a t e d t h e s u b s t a n c e and shown t h a t o t h e r substances c o n t a i n e d m e t h y - lene groups, t h e h y d r o g e n of w h i c h c o u l d b e r e p l a c e d

by sodium 9

A few years l a t e r , C o n r a d showed t h a t a n alcoholic solution of sodium e t h o x i d e would suffice, i n place of metallic sodium or t h e d r y ethoxide, for t h i s t y p e of reaction; he a p p l i e d his m e t h o d in p a r t i c u l a r to t h e preparation of a l k y l malonic esters 1 0

Not only does condensation t a k e p l a c e b e t w e e n two molecules of a n ester s u c h as acetic ester, b u t also b e - tween an ester a n d a k e t o n e A c e t y l acetone can b e prepared, for e x a m p l e , from acetic ester a n d acetone :

OH 3 COOC 2 H 5 + CH 3 CO.CH 3 « CH 3 CO.CH 2 CO.CH 3 + C 2 H 5 OH Propionic a n d b u t y r i c esters u n d e r g o t h e same type of c o n d e n s a t i o n :

SODIUM AND POTASSIUM 7

Iii both cases the carboxyl group of one molecule

of the ester attaches itself to the a-carbon atom ofthe other The yields in both cases are lower thanthat obtained with acetic ester, which is about 25per cent, of that calculated

Isobutyric and isovaleric esters were found byHantzsch11 to follow a different course

The compound which might be expected whenusing isobutyric ester could not be isolated, and wasapparently reduced by the sodium present to eth-oxycaprylic ester, while simultaneously some of itbecamo hydroiysed to hydroxycaprylic acid thus :

Not isolated.

(CXr 3 ) 2 CH.CHo.CH(OC 2 H 6 ).CH.C 3 H 7 COOCoH 5 Ethoxycapvic ester (CH 8 ) 2 CH.CH 2 CH(OH).CH.C 3 H 7 COOH Hydroxycapric acid.

Acetoacetic ester was the first of those compounds

to be studied, which contain the grouping—00 —

CH2—CO— , the hydrogen of the methylene group(CH2) being replaceable, entirely or in part, bysodium Around its constitution and principal re-actions much controversy was destined to take place,and even now the last word has not been heard con-cerning this important and interesting substance.Geuther, endeavouring to show that a secondhydrogen atom of acetic acid could be replaced bysodium, caused the metal to act upon acetic ester.Hydrogen was evolved, sodium ethoxide was formed,and a solid sodium compound was isolated, having thecomposition C0H9O3Na, which on acidifying yielded

an oil capable of forming salts with bases Geutheralso proved that by the action of alkyl iodides thesodium was replaced by alky], and this fact was con-firmed shortly after by Frankland and Duppa.Wislicenus next showed that the product underdiscussion was acetoacetic ester and that two hydrogenatoms were replaceable by sodium in two stages

He represented the reactions in the following manner,adopting the formula of Frankland:

( i ) CH a CO.CHNa.COOC a H 8 + C 3 H 6 I

-CHs.CO.CH(C 2 H 6 ).COOC 2 H 6 + N a l

(ii) CH 8 CO.CNa(C 2 H 6 ).COOC 2 H 5 + C 2 H 5 I =

CH 8 CO.C(C 2 H 5 ) 2 COOC 2 H 5 + N a l

Geuther ascribed the enolic or hydroxylic formula

CH3.C(OH):OH.COOC2H6 to the substance, taining that it explained better its chemical nature.12Claisen was the first to propose an important ex-planation of its mode of formation, and offered a viewwhich is still regarded with favour.13 This view is,that the condensation of acetic ester, and other con-

main-SODIUM AND POTASSIUM 9

densations of this type, take place through theformation and subsequent decomposition of an inter-mediate addition compound, in the formation of which

sodium ethylato plays an important role The stages

of the reaction may therefore be represented thus:

CH 3 CO.CHNa.COOC 2 H 6 + HC1 - CH :i CO.CU a 0OOC 3 H b 4- NaCl

The above intermediate compound has not boonisolated; but by tho interaction of bouzoic molhyl-ester and sodium benzylate an analogous compoundhas been produced and separated

/

C 6 H 5 COOCH 3 + C 0 H 6 CILONa - C U H B C

-Other compounds containing a metliyleno group;the hydrogen of which is replaceable by sodium aud

by alkyl groups, are :

Acetyl acetone CH B CO.Cir 3 OO01I a

Malonic osier 0^000.0JJ 3 COOU s ll fi

Acetone clicarboxylio estor CoH^OOC.CHa.CO.CH

Cyanacotio oster NC.CIt COOC a Ui

Benzyl cyaixido ^ ;

Deoxybenzoin

1 0 SYNTHETIC USE OF METALS

A few applications illustrating the value of thesesodium derivatives may now be outlined

The sodium derivative of acetoacetic ester, pared by treating the ester with an alcoholic solution

pre-of sodium ethylate, is converted into an alkyl stituted ester by boiling with any alkyl iodide:

sub-CH 3 CO.CH 2 COOaH 5 -> CH 3 CO.CH]Sra.COOC 2 H5 - *

CH 3 CO.CHR.COOC 2 H 6

A second radicle II1 may be caused to replace thesecond hydrogen of the methylene group, by repeat-ing the treatment with sodium ethylate and an alkyliodide EaI

CH3.CO.CHRCOOC0H5 -» CH 3 CO.CNaR.COOC 2 H 5 -»

These substituted esters, like aceto-acetic esteritself, can be hydrolysed in two different ways andthus yield a variety of ketones and acids of theacetic series.14

Boiling with dilute acid or dilute alkali brings

about ketonic hydrolysis chiefly :

pre-SODIUM AND POTASSIUM 1 1

replacing one or both of the methylene hydrogens

by an alkyl group :

yCOOC 2 H 5 /COOC 2 H 5 yCOOC 3 H 6

CH 2 ; - * CHR X or C&R 1 (

\COOC 2 H 5 \COOC 2 H 5 \COOC 2 H 5

On hydrolysis these substituted malonic estersgive the corresponding acids and the latter on beingheated to 200° lose carbon dioxide :

yCOOH /COOH

CHEf -»B.CH,.CO0H; CKBF -» ERl CH.COOH

\COOH " \COOH

The monosodium derivative of aceto-acetic ester

on treatment with iodine undergoes condensation to

a dibasic ester (diaceto-succinic ester)

COC 2 H 5 CH(COOC 2 H 6 ) 2

+ Io == • | + 2NaI

OC 3 H 6 " OH(COOC 2 H 6 ) 2

Acetyl aceto-acetic ester is prepared by the action

of acetyl chloride upon the compound 0Hs.0O.0HNa.COO03H5, and on hydrolysis gives acetic andaceto-acetic acids :

CH3.CO.OH.COOC3HB

COCH, CH3.COOH + CH3.C6.CH3.COOH + O 2 H C OH

In a similar manner, by using a-monochloracetone,the y-diketone, acetonyl acetone, is obtained afterhydrolysis15:

12 SYNTHETIC USE OF METALS

CH 3 CO.CHNa.COOCoH (5 + CICH3.CO.CH3 =

CH3.CO.CH.COOC3H5 + NaCl CHa-COCHa

Heating with water at 160° is sufficient to lyso the substitution compound and eliminate carbondioxide :

a change which is sometimes explained by thefollowing steps:

SODIUM AND POTASSIUM 1 3

The behaviour of sodium ethyl aceacetate

to-wards chloracetic ester and chloroformic ester

respec-tive! j y indicates that the compound exhibits dynamic

isomerism because in the first reaction it behaves

as though sodium were directly united to carbon, and

in the second reaction as though the sodium were

From acetyl-acetone a series of j3- or 1:

3-di-ketones can be obtained by treating the mono-sodium

compound with alkvl iodides :

I 3 + CHJE =

CH 3 CO.CH(C2H B ).CO.CH 3 + Nal

Treatment of the sodium derivative with iodine

gives tetra-acetyl ethane :

CH3.CO.CHNa.CO.CH3 CH 3 CO.CH.CO.CH 3

CH a CO.CHNa.CO.CH 3 + * " CH 3 CO.CH.CO.CH f

Aceto-acetic ester is technically valuable in the

preparation of antipyrine The ester is first allowed

to react with phenyl-hydrazine, and the ring

com-pound formed is then convex'ted into antipyrin by

inethyl iodide and sodium :

CH 3 CO.CH 3 COOC S H 5 + CflH fi NH.NH 2

" CH f.- 2 ' CO -° CiI15 + H > ai

1 4 SYNTHETIC USE OF METALS

The hydrazone then loses C2H5OH and formsl-phenyl-3-rnethyl pyrazolon :

This substance is then treated with ISTaOEt andOH3I and the product hydrolysed with loss of carbondioxide:

CN CH, CN CH.,

I I

+ CH 8 I « C.CH 8 CH + N a l COOC 2 H 5 COOCjHg COOCaHa COOC 2 H 5

Hydrolysis COOH CH 3 - C O 2 CH 3 CH 3

COOC 2 H 5 COOC 2 H 6 COOC 2 H 5 COOCjHs

The synthesis of S-keto-hexahydrobenzoic acidfurther illustrates the use of cyanacetic ester.17

- - /innp TT nC\( —

SODIUM AND POTASSIUM 15

The di-sodium derivative is condensed with propionic ester to form y-cyanopentane-a-ye-tricar-boxylic ester :

/3-iodo-C 2 H 5 OOC.C(CN)NA 2 + 2CH 2 I.CH 2 COOC 2 H 5

/CI1 2 CH 2 COOC 2 II,

= C 2 H 5 OOC.C(CN) + 2TSM

\CH 2 CH 2 COOC 2 H 5

Hydrolysis of this cyano-ester gives tricarboxylic acid, which on digestion with aceticanhydride and subsequent distillation yields S-keto-hexahydro-benzoic acid:

OHjBr CH(Na) (COOC 2 H 6 ) 2 CH 2 CH(COOC 2 H 6 ) 2

I + I = | + 2NaBr

CI 2 Br CH(lSra) (COOC 2 H 5 ) 2 CH 2 CH(COOC 2 H 5 ) 2

When the sodium derivative of butane carboxylic ester is acted upon by bromine, the result-ing product is tetramethylene-1 : 2-tetracarboxylicester:

tetra-CH 2 CNa(COOC 2 H 6 ) 2 CH 2 C(COOC 2 H 5 ) 2

CH 2 CNa(COOC 2 H 5 ) 2 + ^ " CH 2 C(COOC 2 H 5 ) 2

The use of trimethylene bromide with sodium

16 SYNTHETIC USE OF METALS

malonic ester will make the following reactionspossible:

/

C COOC2H5

Succino-succinic ester can also be prepared by theaction of sodium upon a-bromaceto-acetic ester.19

SODIUM AND POTASSIUM 1 7

Succino-succinic ester was also used by Baeyerfor synthesising the terpene hydrocarbon p-men-thadiene.21

Succino-succinic ester, like phloroglucin, exhibitsdynamic isomerism (tautomerism), behaving undersome conditions as a keto-body; and under otherconditions as a hydroxylic, or phenolic body havingthis structure:

CH 3 CO.CH 3 + j = CH 3 CO.CH 3 CO.COOC 2 H 5 + C 3 H 6 OH

cc

1 8 SYNTHETIC USB OP METALS

tion is afforded by the syntliesis of acetyl-pyroracemicester, from acetone and oxalic ester :

Cyanacetio ester Benzylidene cyanacetic ester

Sodium has been widely used in the synthesis ofvarious organo-metals and organo-metalloids, bycausing the halides of the elements to react withorganic halogen compounds The following are ex-amples of this type of reaction :23

SODIUM AND POTASSIUM 1 9 S21CI4 + 4C 6 H 5 Br + 8Na = Sn(C 6 H 5 ) 4 + 4NaBr + 4Na01 SiCl 4 + 4C 6 H 6 Br + 8Na => Si(C c H 5 ) 4 + 4NaBr + 4NaCl.

Sometimes the sodium alloy of the metal is utilised,

as in the preparation of tin, lead, and mercury pounds, by means of tin-sodium, lead-sodium, andsodium amalgam respectively :33

in much the same manner as sodium itself

Benzoic ester and acetone yield benzoyl-acetone

C 6 H 5 COOC 2 H 6 + CH3.CO.CH3 = C 6 Hfi.CO.CH 2 CO.CH 3 + C 2 H 6 OH

Sucoinio ester and acetone yield teraconic ester

0 6 1 1 5 0 0 0 ^ 0 0 0 0 ^ 5 +C 2 H 5 OH

C 6 H 6 CO.CH 2 CO.O 0 H 6 + C 2 H 6 OH.

By condensing formic ester with other boxylic esters, aldehyde esters result, while by usingoxalic ester, ketonic dibasic esters are formed:

monocar-2 0 SYNTHETIC USE OF METALS

HCOOC 2 H 5 + CH 3 COOC 2 H 6 = HCO.CH 2 COOC 2 H S + C 3 H 6 OH

Formyl acetic ester.

COOC,H 5 CH a COOC,H 5 CO.OH 3 COOC 2 H 5

COOG 2 H 6 CII 3 GOOC 2 II 5 CO.CH 2 COOC 2 U 5

Diacetyl dicarboxylic ester.

Pormyl acetone may be prepared by using formicester and acetone:

HCOOC 2 H 5 + CH3.CO.CH3 = HCO.CH S CO.CH 8 + C 2 H 5 OII

This substance can be farther condensed by aceticacid to triacetyl-benzeno:

CH / C H O

CH,.CO.CH 3 CH a CO.C C.COCH 3

Bing condensations with oxalic ester are : cyclopentane dicarboxylic ester from oxalic andglutaric esters :25

Diketo-COOC 2 II 5 CH 2 —COOC.J-I5 CO—CH~-COOO 2 H 5

OIL—COOC 2 H 5 OO—CH— COOC 2 H h

By using /3j3-dimethyl glutaric ester, Konnnpaobtained diketo-apocamphoric ester which was usedfor the synthesis of camphoric acid :26

COOC 2 H 5 CH 2 COOC 2 H 6 CO—CH.COOC.ir 6

C(CII 3 ) 2 era

COOC 2 H 5 CHo.COOC 2 H 5 CO—OH.COOC 2 H 6

(CH a ) 2 + 20Jtl k OK

SODIUM AND POTASSIUM 2 1

A methyl group was introduced into the lattercompound by the aid of sodium and methyl iodide,and the resultant compound reduced and thenhydrolysed to dihydroxy-camphoric acid:

to racemic camphoric acid :

Sometimes the oxalic ester only undergoes condensation as in the formation of oxalyl aceticester:

2 2 SYNTHETIC USE OF METALS

Clio + HCOOC 5 H n C: CHOH

of amyl nitrite in the presence of sodium ethylate :

CflH 5 CO.CH 8 + CcH^.O.NO « C C II 5 CO.CH: NOH + C 6 H n O H

An example of this class of condensation withelimination of water is the formation of a-phenyl-cinnamic nitrile, from benzaldehyde and benzylnitrile:

C (1 H, C C H 5 CH : C.C fl H 5

SODAMIDB AS A SYNTHETIC AGENT.

This substance was utilised by Claisen in 1905, foralky latin g ketones and for preparing 1 :3-diketones.Its action seems to bo quieter and more regular thanthat of sodium or sodium ethylate.28

One or two ethyl groups may be introduced intoacetophenone by using ethyl iodide with sodamide :

SODIUM AND POTASSIUM 2 3

1: 3-Diketones are prepared by condensing ketoneswith esters

Acetyl acetone from acetic ester and acetone:

CH 3 COOC 2 H 5 + OH 8 CO.CH 3 = CH 8 CO.CH 2 CO.CH 3 + G f t O H

Benzoyl acetone from acetic ester and phenone:

aceto-CH3.COOC0H5 + CH 3 CO.C C H 5 = CH 3 CO.CH 2 CO.O G H 5 + C 2 H 5 OH.

The powdered sodamide is added gradually to themixed substances, cooled in ice, and after standingfor some time, the mixture is treated Avith ice-coldwater and the product precipitated by acidifyingwith acetic acid

Hydroxymethylene ketones are formed by usingformic ester:

CH3.CO.CH3 + HCOOR = CH3.CO.CH : CHOH + EOH.

Sodamide has been technically applied in at leasttwo instances, namely, the production of cyanide byCastner's process and also the production of indigo

In the preparation of cyanide, the sodamide ismixed with carbon and the mixture subjected to a dullred heat, when the following reaction takes place:

NaNH 2 + C =» NaCN + H 2

Indigo can be synthesised according to theGerman Patent 158,089, by heating sodamide withthe diethyl ester, or the diamido-derivative, ofphenyl-glycocoll-carbonic acid, in benzene solution :

.NH.CH 2 COOH N H V

4 < -> C fl H 4 < >CH 2 + H.>0 + COo XJOOH M X ) '

Indoxyl

The indoxyl formed is converted into indigo byexposure to air

2 4 SYNTHETIC USB OF METALS

Metallic sodium has recently received important

application as a polymerising agent in the mation of isoprene into artificial rubber.29

transfor-The steps in this important synthesis, startingfrom starch, are as follows :

The starch is fermented to fusel oil and acetone,and from the former liquid, isoamyl alcohol isseparated

By treatment with hydrogen chloride, isoamylalcohol is converted to the monochloride, and thevapour of this when acted upon by chlorine gasleads to the formation of three isoamyl dichloindes :

(CH : 0 2 CH.CK,CH 2 OH + HC1 = (CH :l )oCH.CHo.CH 2 Cl + H 3 O

S (CH:) ) 2 CH.CHC1.CH 2 C1 + HC1 (CH.)) 3 CH.CH n CH 2 Cl + C l ^

^ :<N >CH.CHo.CH 2 Cl + HC1 CHoCK

These isoamyl dichlorides, when heated with lime,lose hydrogen chloride and pass to isoprene (methyldiviflyl) :

*\c.CH : CH2

CH/'

Isoprene on standing for some time with metallic

sodium becomes converted into synthetic rubber.

SODIUM HYDROXTDE.

This sodium derivative is generally utilised inaqueous solution for condensation work, the concen-tration often being 10 per cent

Schmidt30 was the first to use the reagent, in 10

SODIUM AND POTA8STUM 2 5

per cent, aqueous solution, for condensing togetherfurfurol and acetaldehyde :

C 4 II :i O.CIIO + CH n CO.CH 3 = C 4 H 3 O.CH : CH.CO.CH 3 + H U O.

Using benzaldehyde and acetone, he obtainedmono- and di-benzylidene acetone

Further examples of condensation of this class ai-ethe formation of indigo from o-nifcrobenzaldehydeand acetone, and the formation of quinoline fromo-aminobenzaldehyde and acetaldehyde:

C l i o >CHOH.CHo.CO.CHa

C G H 4 < + CH,.CO.CH., - C 0 H 4 <

\isro2 ' ' \tfo2

o-nitrophenyl-lactic acid ketono.

This product is then decomposed by the excess ofsodium hydroxide :

y CHOH.CHo.CO.CH 3 2C 0 H 4 <

2 6 SYNTHETIC USB OF METALS

days the transformation was complete : u

CH 2 OH CH 2 OH CH 2 OH CH 2 OH

CHOH + CO ~ CHOH CO

CHO CH 2 OH CHOH — OHOH

(Q-lycerose) a-acrose (inactive fructose).

By the same method; glycollie aldehyde has beenpolymerised to erythrose :

CH 2 OH CHO CH 2 OH CHO

CHO CH 2 OH CHOH - CHOH

Cinnamic aldehyde can be formed from

benzal-8ODITJM AND POTASSTTJM 27

dehyde i*11 ^cetaldehyde, and the product can be

again c° tX(^n^ed with acetaldehyde or acetone :

l O H 0 C 6 H 5 CH : CH.CHO + H 2 O

: CH.CHO + CH 3 CHO = : CH.CH: CH.CHO + H 2 O Cinnamyl acrolein.

: CH.CHO + CH v CO.CH.j

-^ : CH.CH :CH.CO.'CH> + Ha O Oinnamyl-vinyl-methyl ketone.

If t\^c> l u° l e c u l a r quantities of cinnamic aldehydebeused> ^J"0^ i n t h e last case di-cinnamyl-vinyl ketoneresults

Anofcl*cn* c r t s e of quinoline formation is the

con-^ Toenzoyl acetone and aniline, resulting in

OHI a I + NaOH = C c H 5 CHCISr + Nal

QuinotioH c a n be prepared by condensing 1: diketorioH by nquoous sodium hydroxide.30

2-In tli o first p l a c e an unsaturated 1 : 2 : 5-triketone

is fonuocl wliich Tby further condensation passes to aquinom># D i a c e t y l gives first dimethyl-quinogen andthen ^ - x

2 8 SYNTHETIC USE OF METALS

CO CH3.CO.CO.CHS CH3.C.CO.CH3 CHVC O i l

' II II + 2TT,0 CH.j.CHo.CO.CO.CH-, CH,.C C.CH,

The reaction may be expi*essed in a general waythus :

CO X.CHo.CO.CO.Y X.C.CO.CO.Y XC CY

-» II -> II II Y.CO.CO.CHo.X Y.C.CO.CH X YC CX

A further example of condensation by sodiumhydroxide is afforded by ionone, used as a substitutefor essence of violets, which is formed from citraland acetone.37

Pseudo-ionone is the first product, and this is thenconverted to a mixture of a- and j3-ionone by boilingwith dilute sulphuric acid :

(CH 3 ) 2 C:CH.CH 2 CH 2 C(CH 3 ):CH.CHO + CH 3 CO.CH 8 (CH 8 ) 2 C:CH.CH 2 CH 2 C(CH 3 ):CH.CH:CH.CO.CH 3 + H 3 0.

-The next stage is explained by the followingscheme:

SODIUM AND POTASSIUM 29

A commercial process in which potassium may beregarded as a synthetic agent is Beilby's process forpreparing cyanide, by heating a mixture of potas-sium carbonate and carbon in ammonia

Potassamide is probably an intermediate compound,and tho method corresponds to Castner's cyanideprocess:

K a CO 8 + 2NH 3 + 2C - 2KNH 2

2C