US1998488A

US1998488A - Hydrazo compounds and inversion thereof

Info

Publication number: US1998488A
Application number: US464702A
Authority: US
Inventors: William S Calcott; Frederick B Downing; Norman C Somers
Original assignee: EI Du Pont de Nemours and Co
Current assignee: EIDP Inc
Priority date: 1930-06-28
Filing date: 1930-06-28
Publication date: 1935-04-23
Anticipated expiration: 1952-04-23

Description

Patented Apr. 23, 1935 UNITED STATE PATENT OFFlCE liroaazo coMroUN INVERSION a a THEREOF William S. CaIcott, Pennsgrove, and Frederick B.v D nin and Norma 6. Seniors, Gamers Poin J assigno to I- u P nt e Nemours & Company, Wilmington, DeL, a, corporation o Delawar NoDrawing Application June28, 1930,

' Serial No. 464,702

1" 2r Ql'ainis. r01. maniacs) This invention relates to hydrazo compounds and their production, from nitro-benzenes. It i also relates to the inversion of hydrazo-benzenes to benzidines. More particularly it deals with r the formation of hydraze-benzenes in a new Cain & Thorpe, 1918, page 22).

The general course of this reduction reaction; is well understood, for example it has beenpointed out that the alkaline reduction of nitrotoluene (a representative of this class) takes thefollowing course (Zeit. Ang. Chem. 13, 135).

. Nitro-tolucne Nitroso-toluene Tolyl-hydroxyI amine When the alkaline. reduction of nitro-lbenz enes to hydrazo-benzenes by means oi zinc, and caustic is carried out in an aqueous a very 7 poor yield is obtained, 70% or more of the final It is also known that the.

of hydrazo-benzenes it involved the additional expense of alcohol recovery.

Izmailskii (U. S. 5. Russia Paton 116 of Feb. 28, 1925) and Nelsonand Prasial (U. S. Patent 1,644,484 of October 4, 1927) have recently suggested that this reduction be performed in'the presence of a solvent; not miscible with water. This method gives better yields than are 0btained in anraqueous medium but like the reaction in anra'lcoholic medium mentioned above involves the cost of solventrecovery.

As a third alternative, the reduction may be carried to the amt-benzene stage or somewhat further, without the use of any solvent or dil uent whatever, other than the water introduced with the caustic solution usedto activate the zinc; this water being less than 10% of the weight of the nitro-body. By the azo-benzene stage; it is intended to refer to that portion of the reaction where the amount of the azobenzene present is near the maximum; or where the melting point of the mixture begins to rapid- 1y approachll5' C. After this stage is reached as the reduction. continues, the freezing point of the charge rapidly rises, and it is therefore necessary to introduce some diluent with which the well agitated mass may-be mixed to avoid its solidifying (at the reduction temperature desired), into arigid cake and thus stopping the reduction. It has been customary, therefore, in this method, to add to the well agitated reduction mass, when its melting point begins to rise rapidly, an amount of hot water from once to twice the weight of the nitroetoluene charged... Thereafter the reduction has been completed by further addition of zinc and; sodium hydroxide, yielding pellets of hydrazo-toluene together with zinc sludge These pellets have the form of irregular granules averaging from 1 to- 3- diameter; l l

When the inversion to henzidines is made by treatment with acid (for example, hydrazo-toluone to tolidine), the reactions chiefly occurring Hydrazo toluene Ditolyline on; 0H; on o Er Ha L Tglifiill i QHa CH! It has been found that the hydrazo-benzene pellets, produced according to the prior art, due to their density, smooth surface, and form, are entirely unsuited for economical inversion to benzidines by treatment with acid, the reaction being extremely slow.

For this reason, in the past it has been found advantageous to invert the hydrazo-benzene by one of two general methods. .According tothe.

first the difiicultly reactive pellets have been dissolved in a solvent and by the second they have been disintegrated preparatory to treatment with acid. Both methods are inherently expensive and involve losses by oxidation of the hydrazo-ben- .zene. In the solvent method the pellets have been dissolved in some substance such as alcohol, solvent napthaor benzene and agitated with aqueous acid of suitable strength. This method involves the expense of solvent recovery and yields comparatively large portions of di-tolyline. In the pellet, disintegration method an attempt to decrease the oxidation losses of hydrazo-benzene in grinding has been made byutilizing apparatus which excludes air. This is an additional cause for expense. Whether disintegrated in the presence or absence of air the treatment of the hydrazo compoundwith acid hasrusually followed as quickly as possible to further decrease the'loss by oxidation.

It is obvious, therefore, that the prior art methodsillustrated above, all possess undesirable and disadvantageous characteristics.

This invention has for an object the preparation of hydrazo-benzenes in a new physical form 'and improved methods for producing such compounds. Other objects are to devise new processes for the preparation of benzidines and to devise processes which will increase the yield and quality of hydrazo-benzenes and benzidines. Other objects will appear hereinafter.

The above objects are accomplishedby the present invention whereby the reduction of nitrobenzenes to hydrazo-benzenes is. carried out in the presence of a protective colloid and whereby the. resultant hydrazo-benzene is inverted to a benzidine in the presence of a mineral acid.

It was shown above that in the production of hydrazo-benzenes, the reduction of nitro-benzene to the azo-benzene stage or further may be carriedvout without the addition of any solvent or diluent. It has now been discovered that if,

at this stage, a quantity of water be added sumcient to carry the reduction products in suspension and containing an amount of protective colloidsuflicient to form an emulsion of the reduction products in the water, the reduction may then be completed by further additions of zinc and caustic with numerous advantages. Theinvention will be readily understood from the consideration of the following examples.

Example '1 0.2% aqueous soap solution a't"100 c-qwer'e rap-. idly added and the reduction continuedby the addition of more zinc until the reduction mass was a light gray color, showing that the hydrazo stage had been reached.

The hydrazo-benzenes produced by the process set out above may be substantially freed from zinc-hydroxide by treatment with sulfuric acid. This will be clear from the following explanation.

The slurry resulting from the above process was Example II Into a vessel provided with an agitator and cooling coils was charged 10% hydrochloric acid by weight, in about excess of that theoretically required for the inversion. This acid was cooled to 0 C., and into it was shovelled, graduallywith good agitation the moist, highly dispersed hydrazo-toluene, the temperature being kept under 10 C. until inversion was complete, as shown by chemical tests. after which the charge was heated to 70 C. and sufficient water added to dissolve the tolidine-hydrochloride. After this point the tolidine was freed from the toluidineby precipitation of tolidine sulfate and filtration. The base was then formed with sodium carbonate in the customary and well known way.

The protective colloid preferred is usually some water soluble salt of a fatty acid commonly termed a soap. Other protective colloids may be used however for example, a member or memers of the group exemplified by Turkey red 01], glue, casein and the water soluble fraction of sludge acids (such as result from the treatment of petroleum oils or fractions thereof with sulfuric acid). The strength of the water solution of the protective colloid may vary but the solution need not ordinarily contain more than 5% of the colloid.

In the separation of the zinc from the hydrazobenzenes the reactions may be carried out at ordinary or reduced temperatures. The preferred strength of sulfuric acid is from 10 to 20% although stronger or weaker acid may be used if desirable. The length of treatment with the sulfuric acid may be varied as desired although usually 20-30 minutes sufiices for solution of the zinc. The minimum amount of sulfuric acid is that molecularly necessary to change the zinc present to zinc sulfate, but ordinarily an excess of acid is used. The excess should be as small as possible due to its effect on the hydrazo body and under usual operating conditions 25-50% excess is sufficient.

The quantity and identity of the mineral acid used for the inversion may vary, but it is preferred to use hydrochloric acid in concentrations of from 5 to 20% by weight. The use of nitric or other oxidizing acid is not permissible. It is to be understood that otherconcentrations and other mineral acids may be used. Preferablythe temperatures usedfor inversion are below 10C; Y r

'Whil thisinvention is not limited to any benzidines:..

a p 7 V v V reac es: specific" ,nitro-benzene certain'nitro bodies concerning which thislinvention has particular imf portance are: Intro-benzene, nitro-toluene,".ni-v

tro-anisol, and their hornologues; i

' The invention herein disclosed has numerous advantages among which are convenience. crop oration and substantially quantitative yields "of The hydrazo-benaene producedthisprocess isjin the form of extremely fine particles readily oseparableby filtrationxand, capable of. being in-' verted by an aqueous acid with great speed and v with improved yields.- This productfmayornore over-he handled commercially with great'freeiiom ofj ,OXt-datio'n probably due to the protecting ac-v tion ,ofthe thin. coat of colloid whichiadheresto r ITrisinventionavoids siredto -limit ittherebyQ I a -1 As many apparently widely difierent embodi .ments of'this invention maybe made without. 1 departing from the spirit and scope thereof, it isto be understood that we do not limit ourselves,

the particles.

While certain theories have been :set out to aid in understanding the invention itis not deto; the specific embodiments thereof. except as defined in the appended claims. 1

We claim: i I

1. The process comprising adding to about 10% parts of .ortho-nitro-toluene, small increments of zinc and a dilute solution of alkali-metahhydrox ide vlilelmaintaining the temperature at about lOll C to about 115 0., until the nitro-toluene has been reduced to the ,ace-toluene.,stagefaddingf aoout 200 parts of an aqueous approximately,

2% soap solution whichihas a temperature of 'about 19;)". C.,;ccntinuing theaddition of zinc'and alkaliemetalhydroxide until the charge hasbeen reduced to the 'hydrazo-toluen'e stage, Washing the resultant product with'about lQ-2G% sulfuric o acid for from 2fi-3iltminutes; at not greaterthan ordinary temperatures, thereafter adding the said product; in small increments to an approximately 10 hydrochloric acid solutionheld at about 0 10,, the" said hydrochloric acid being in an amount. about twice that, theoretically necessary to convert thefhydrazo-{toluene compound. to

C.' to about C until the nitro benzene L hasbeen reduced to'the azosbenzene stage adding about 200 parts oi an aqueous approximately 2%.

soap solution which has atemperature of about 100 C., continuing the addition of zinc and alkali-Inetal hydroxide until the charge has been reduced to the hydrazo-benzene stag'eQweshing H the resultant productwith about l,0%20% sulfuric acid for from 20-30 minutesat not greater than ordinary temperatures, thereafter adding the said product'in small increments to an approximately 19% hydrochloric acid solution held at about 0 ,C., the said hydrochloric acid being in an amount about 200% of that theoretically necessary to convert the hydrazo-benzenecompoundto a ben-' zidine, maintaining thetemperature below about J I 10 until the inversion to the benzidine is sub- 3 thereon; H g a, V V V w f 55l-Iydrazo-benzenes in thflfilllll of hue par,- iticles and having a'coating oi soap thereon.

. w '6. In the'pro'cess of inverting'hydrazo-benzenes the steps or finely dividing the hydrazo-be n zen'e r the necessity of disinte gr'ation oi'thesolid hydrazo-benzenes and the reccvery oi solvents fromthe variousstages of the reaction. Y

; face thereof whichfis substantially stantially complete and separating the benzidine compound; a 3Hydrazou toluene in the form offine particles;

-' having acoating; of soap thereon and character izedby great freedcmirom oxidationj- L er'l-Iydrazo-benzenes intheiorin of fine par ticlesand having a coating of a protective'col ida-nd coating' the surface of the particles'gwith a protective colloid.

7; The processor producing hydrazo-toluene which comprises treating orthc-nitre-tcluene with sufncient this and dilute alkali to convert it 7 to the azo toluene stage While maintaining the temperature at about 100 C'. to about;ll 5 C thereafteradding an aqueous solution of a pro-- tective colloid, continuing the reduction" to hydraso-toluene, and separating "the: hydraa toluene. i

8'. The processor producing hydrazo-be'nzenes which co'inprisestreating nitro-benzenes with suificient'zinc and dilute alkali to'corivert them to the azc benaene stage while};maintaining the: temperature at aloout C.'to about 115. 0.,

thereafter adding an aqueous solution of aproi tect'ive colloid, continuing the reduction tohydrazo-henzenes; and separating the hydrazo bem 9. The 'hydra'zo toluene body in the form of particles having a protective colloid on the suridentical with that resulting ircm the process of producing hydrazo-toluene which corn-prises treating orthonitro-toluene with sufilcient zinc and dilute alkali to convert it to the arc-toluene stage while rnain- -t tairnngthe temperature atabout C. to about 115 C., thereafter adding an'aqueous solution ofa'prfotective colloid, continuing the reduction to hydrazo-toluene, and separating the hydrazotoluene body. 7 r l 1G. The hydrazo benzene bod-y the form of particles-having a protective colloid on the sur-' face therecf'which is substantially identical with that. resulting from the process of producing hy draZo-Toenzenes which coniprises'treati'ng Introbenzenes with suflicient Zinc and dilutealkali to convert said nitro-henz ene to the 'azo benzen'e st-age'while maintaining the temperature at acout 106 (1. to about1l15 Q, thereaiter adding' an' aqueous solution of a protective colloid, continuing the reduction toJhydrazo-b'enzenes, and separating the hydrazo-benzene bod-y.

11.1The processor obtaining high yields of ,hydrazo-benzenes from nitro-henzenes compris 'ing treating a intro-benzene with increments oi zinc and dilute'alkalnmetal hydroxide to-reduce it totheazo-benzene stage; addinga protective colloid in water and continuing the addition of .zinc and hydrox de until a hydrazo-benzene is produced and then separating it;

I 12. The process of obtaining high yields ofhydrazo-benzenesfrom nitro benzenes 'comprising treating a nitrobenzene withincrements of zinc and dilute alkali metal hydroxide to reduce it to the aZo-benzene stage, and adding water containingrwater'soluble soap.

13. The process of obtaining high yields of hydrazo-benzenes from nitrobenzenes comprising'treating a nitro-bnzene with increments of zinc and dilute'alkali-metal hydroxide to reduce it to the azo-benzene stage, adding a. soap solu-.

tion andcontinuing the addition of. zinc and hy-' droxide until a hydrazo-benzene is produced and then separating it. I

14. The process of obtaining, high yields of hydrazo -benzenes from nitro benzenes comprising treating a nitro-benzene with increments of zinc and dilute alkali-1netal hydroxide to'reduce it to the azo-benzene stage, and adding a soap solution of concentration less than 5% and continuing I the treatment with zinc a'nd hydroxide to form the hydrazo-benzen'e. I 1 I "15. The process of obtaining high yields of hydrazo-benzenes from nitro benzenes comprising treating a intro-benzene with increments of zinc and dilute alkali-metal hydroxide to reduce it to the azo-berizene stage, adding a dilute soap solution in an amount surficient' to cause, the

hydraZobenZene to be formed in small particles and continuing the treatment with zinc and hydroxide to form the hydrazo-benzene. v

16. The product which is substantially identical with thatresulting from the process of obtaining high yields of hydrazo-benzenes from nitrobenzenes comprising treating a ,nitro-benzene with'increments of zinc and dilute alkali-metal hydroxide to reduce it to the azo-benzene stage,

' adding a'dilute soap solution in an amountsufsmall particles and continuing the addition of zinc I ficient to cause the hydrazo-benzeneto be formed in small particles. I

17. The method ofproducingimproved yields of finely divided, oxidation resistant hydrazoe toluene comprising treating nitro-toluene with increments of zinc and dilute alkali-metal hydroxide to reduce it to the also-toluene stage, adding a dilute soap solution in an amount sufficient to cause the hydrazo-toluene to be formed in andhydroxide until arhydrazo toluene is produced and'then separating it. 18. The method of producing improved yields of finely divided, oxidation resistanthydrazm' benzenes comprising treating nitro-toluene with increments of zinc and dilute alkali-metal hye droxide to reduce it to the azo-toluene stage, add-v ing a dilute soap solution in an amount sufficient to cause the hydrazo-toluene to be formed in small particles and continuing theadditionof zinc and hydroxide until a hydrazo-toluene is produced and then separating. it.

19,1-Iydrazo-benzenes in the form of fine particles having a coating of a protective colloid thereon and-characterized by great freedom from oxidation. I y I 20. The process of producing. hydraZo-toluene which comprises treating ortho-nitro-toluene with sufficient zinc and dilute alkali to convert it to thegazo-toluene stage while'maintaining the temperature at about 100 C. to about 115 0.. thereafter adding an aqueous solution of a protective colloid, continuing the reduction with zinc and dilute alkali to hydrazo-toluene, and separating the hydrazo-toluene.

21. The process of producing hydrazo-benzenes which comprisestreating a nitro-benzene with sufficient zinc and dilute alkali to, convert it to the azo-benzene stage While maintaining the temperature at about 100 C. to about 115 C., thereafter adding an'aqueous solution of a protective colloid, continuing the reduction with zinc and dilute alkali to hydrazo-benzenes, and separating the hydrazo-benzenes.

' 22. The hydrazo-toluene body in the form of particleshaving a protective colloid on the surface thereof which is substantially identical with that resulting from the process of producing hydrazo-toluene which comprises treating' lorthonitro-toluene with sufiicient zinc and dilute'alkali to convert it'to the azo-toluene stage while maintaining the temperature at about 100 C.

to. about 115 0., thereafter adding an aqueous 7 solution of'a protectivecolloid, continuing the re-v duction with zinc and dilute alkali to hydrazotoluene, and separating the'hydrazo-toluene body. 23,. The hydra'zo-benzene body in the form of particles having a protective colloid on the surface thereof which is substantially identical with that resulting fror'n'the process of producing hydrazo'-benzenes which comprises treating ni-' tro-benzenes with sufficient zinc and dilute alkali to convert said nitro-benzene to the aZo-benzene stage while maintaining the temperature at about 100 C. to about 115 C., thereafter adding an aqueous'solution'of a protective colloid, continuing the reduction with zinc and dilute alkali to hydrazo-benzenes, and separating the hydr-a'zobenzene body.

24; Hydrazo-benzenesin the form of fine particles having thereon a coating of a protective colloid from the group consisting, of soap,Turlceyred oil, water soluble sludge acid fraction, glue and casein; r

25..'In the process of inverting hydrazo-benzenes by treatment with non-oxidizing mineral 'Iurkeyred oil, glue, water soluble sludge acid fraction and casein. II I 27. In' the process of inverting hydrazo-benzenes by treatment with non-oxidizing mineral acids, the steps comprising finely dividing the hydrazo-benzene. and coating the surface of the particles with Water soluble sludge acid fraction. I

WILLIAM S.'CALCOTT.

' FREDERICK B. DOVVNING.

NORMAN C. SOMERS.