On Sulphonfluoresceïn and some of its Derivatives 1

On Sulphonfluoresceïn and some of its Derivatives 1

On Sulphonfluoresceïn and some of its Derivatives

 

Author: C. Willard Hayes

Contents.

p.

 

Introduction 3.

I Ortho-sulpho-benzoic acid.

Preparation from toluene and H_{2}SO_{4} 7.

” ” para-nitro-toluene and H_{2}SO_{4} 8.

Oxidation of toluene-o-sodium sulphonate 12.

Preparation of Sulphinide from ” ” 14.

” ” ” by chlorsulphonic acid. 17.

Conversion of sulphinide into o-sulphobenzoic acid. 25.

Analysis of and crystallography of ” ” ” 28.

II Sulphonfluoresceïn--previous attempts 29.

Preparation and purification of s-fluoresceïn 30.

Analyses of ” 34.

Properties of ” 35.

Salts. Ba. and Ca. of ” 37.

Acetyl derivative of ” 41.

Br substitution products of ” 42.

Action of H_{2}SO_{4} on ” 44.

Action of HCl on ” 45.

Reduction of ” 46.

Conclusion. 47.

 

 

 

 

On Sulphonfluoresceïn and some of its Derivatives.

 

 

Introduction.

 

 

The close analogy in composition and structure between phthalic acid

and ortho-sulpho-benzoic acid suggests the possibility of obtaining

from the latter, by its action on phenols, substances analogous to

the phthaleïns. If such compounds could be made they would afford

a favorable opportunity of studying the effects produced in the

properties of a compound by the replacement of CO by SO_{2}. It was

with a view to such study that the following discussed work was

undertaken at the suggestion of Prof. Remsen and carried on under his

constant guidance.

 

Some experiments previously performed by Remsen and Palmer (A.G.)

indicated the possibility of the formation of a fluorescent substance

by the action of ortho-sulpho-benzoic acid on resorcin but they did

not succeed in obtaining any definite crystallized compound from the

reaction.

 

The chief obstacle to be overcome in the work is the difficulty in

obtaining the o-sulpho-benzoic acid and a large proportion of the

work here described was applied in that direction.

 

 

Ortho-sulpho-benzoic acid: Methods for its preparation.

 

 

1. From toluene and H_{2}SO_{4}.

 

A method employed by Remsen and Fahlberg (Am. Ch. Jour. Vol. 1.

p __ ) for getting the sulphonic acid group in the ortho position to

methyl was; (a) treat toluene with fuming H_{2}SO_{4} forming thus

ortho- and para- toluene sulphonic acids, (b) make the calcium salt

of the sulphonic acids thus formed and from this the potassium

salt. (c) treat this mixture of potassium toluene sulphonates

with phosphorous penta-chloride forming the corresponding

sulphonchlorides. One of these (para) being a solid and the other

(ortho) an oily liquid a nearly complete separation could be

effected. The difficulty with this method is however that the larger

part of the product is the para and only a comparatively small

proportion of the ortho compound is formed.

 

 

2. From p-nitro-toluene and H_{2}SO_{4}.

 

A second method employed consists in starting with p-nitro-toluene.

This when treated with H_{2}SO_{4} forms toluene p-nitro o-sulphonic

acid. If now a method could be obtained for removing the nitro group

the desired result would be attained.

 

The attempt was made by Remsen and Palmer (A.G.) to accomplish this

by (a) reducing the nitro compound to the amide, (b) making the diazo

compound and (c) boiling this with absolute alcohol. According to

generally accepted views this should effect the removal of the diazo

group and its replacement by hydrogen.

 

Experiments however showed that the replacement was made not by

hydrogen but by the ethoxy group -OC_{2}H_{5}. This method was

therefore impracticable.

 

A modification of this method was suggested by an observation of

Baeyer and Liebermann that if phenyl hydrazine be boiled with a

dilute solution of copper sulphate the hydrazine group is replaced

by hydrogen and benzene thus formed. Hence it was believed that if

the hydrazine compound should be made from diazo compound mentioned

above, the corresponding hydrocarbon, i.e. toluene o-sulphonic acid

could be obtained. The results of experiments showed that this

afforded a practicable method of preparing toluene ortho-sulphonic

acid.

 

After experimenting with various modifications of the method the

following was found to be the best adapted to the purpose.

 

The potassium salt of toluene p-nitro-o-sulphonic acid is easily

obtained, as already stated, by heating p-nitro toluene on the water

bath with three times its weight of fuming H_{2}SO_{4}, neutralizing

with chalk and to the solution of calcium salt thus obtained adding

a slight excess of K_{2}CO_{3}. On filtering from. the precipitated

CaCO_{3} and evaporating slightly, the salt is obtained in long

needle shaped crystals of a pale straw yellow color. This is

 

┌─

│CH_{3}

C_{6}H_{3}┤SO_{2}OH (o)

│NO_{2} (p).

└─

 

The reduction of the nitro group is best effected by means of tin and

HCl, in the proportion, salt 5 parts, tin 6 parts and concentrated

HCl 30 parts.

 

The amido acid forms a compound with tin which crystallizes from the

HCl together with stannous chloride. This compound may be broken up

and the tin removed by continued boiling with water.

 

A better method of removing the tin is by dissolving the compound in

Na_{2}CO_{3}. This forms a salt with the amido acid and throws down

the tin as Sn(OH)_{2}, a white flocculent precipitate. On filtering

and adding to the solution conc. HCl, the free amido acid is

deposited in characteristic colorless, rhombic crystals, having the

formula

 

┌─

│CH_{3}

C_{6}H_{3}┤SO_{2}OH (o)

│NH_{2} (p)

└─

 

The method at first employed for preparing the hydrazine compound

consisted in treating the amido acid, suspended in HCl, with

potassium nitrite and then with stannous chloride. The tin was then

removed from the solution by the addition of sodium carbonate and the

hydrazine compound thrown down with HCl. This method however gave

poor results the yield being only about 50% of the theoretical.

 

Another method was accordingly substituted for the above, namely that

of Strecker and Römer (Ber. IV. s 784.) By this the diazo compound

is made first and isolated. This is done by suspending the finely

powdered acid in absolute alcohol, cooling and passing a current of

the oxides of nitrogen through in the ordinary way. The acid changes

in appearance, becoming more crystalline and slightly darker and

settles quickly on being shaken. The reaction here may be expressed

thus--

 

┌─ ┌─

│ CH_{3} │ CH_{3}

C_{6}H_{3} ┤ SO_{2}OH + HNO_{2} = C_{6}H_{3} ┤ SO_{3} + 2H_{2}O

│ NH_{2} │ \

└─ │ N=N

└─

 

When the reaction is completed as shown by the appearance of the

suspended powder it is filtered and while still fresh is added to a

solution of acid sodium sulphite as long as it continues to dissolve

readily.

 

To this solution there is added a quantity of solution of acid

sodium sulphite equivalent to that already used and the solution is

then boiled. It has at first a deep red color but in a few moments

becomes light reddish yellow. The reaction of HNaSO_{3} on the diazo

compound may be represented in two stages, the first portion forming

an addition product and the second acting as a reducing agent. Thus,