Process for the Preparation of Symmetrical Azodinitrile Dicarboxylic Acids from Keto Acids

Europaisches Patentamt European Patent Office CO Publication number: 0 436 183 A1 Office europeen des brevets

EUROPEAN PATENT APPLICATION

245/04 © Application number: 90124725.4 © mt. ci.5: C07C

@ Date of filing: 19.12.90

® Priority: 26.12.89 US 456901 Akron Ohio 4431 3(US) 26.12.89 US 456886 26.12.89 US 457058 @ Inventor: Lai, John Ta-yuan 3465 Ridge Park Boulevard @ Date of publication of application: Broadview Heights, Ohio 44147(US) 10.07.91 Bulletin 91/28

@ Designated Contracting States: «) Representative: von Kreisler, Alek, AT BE CH DE DK ES FR GB GR IT LI LU NL SE Dipl.-Chem. et al Patentanwalte Von Kreisler-Selting-Werner, © Applicant: The B.F. Goodrich Company Deichmannhaus am Hauptbahnhof 3925 Embassy Parkway W-5000K6ln 1(DE)

@ Process for the preparation of symmetrical azodinitrile dicarboxylic acids from keto acids.

O II R1CR2COOH

is reacted with M(CN)X and an ammonia source to obtain an aminonitrile metal carboxylate of the formula

I x M(OOCR2C-NH2)X CN

5 The aminonitrile metal carboxylate is reacted with Mi (OCI)X with the proviso that no alcohol or surface active acid the agent is utilized to form a metal salt of an azo compound. This metal salt is reacted with mineral to give CO symmetrical azodinitrile compound of the formula 00

CO R, CO ?> HOOCR2C-N=N-CR2COOH CN CN Q_ HI from 1 Ri is an alkyl group containing from 1 to about 12 carbon atoms and R2 is an alkylene group containing to about 12 carbon atoms. M is a metal comprising lithium, sodium, potassium, magnesium or calcium; Mi is a

Xerox Copy Centre EP 0 436 183 A1 metal comprising sodium, potassium or calcium; and x is the valence of M and Ml In other embodiments, the preparation of mixed, symmetrical azonitrile initiators and mixed azodinitrile initiators via hydrazo intermediates, prepared from keto acids and aminonitrile and keto acids and a hydrazine source, a ketone and hydrochloric acid respectively is disclosed. EP0 436 183 A1

PROCESS FOR THE PREPARATION OF SYMMETRICAL AZODINITRILE DICARBOXYLIC ACIDS FROM KETO ACIDS

FIELD OF THE INVENTION

The present invention relates to an improved process for the preparation of symmetrical azo initiators from keto acids utilizing a metal hypochlorite. 5 In another embodiment, the present invention relates to an improved process for the preparation of mixed, symmetrical azonitrile initiators utilizing a metal hypochloride. In still another embodiment, the present invention relates to an improved process for the preparation of mixed azonitrile initiators utilizing hydrazine.

w BACKGROUND

It is known in the art to prepare azo compounds from a tertiary amine. U.S. Patent No. 3,783,148 (Fuchs, January 1, 1974) relates to the preparation of symmetrical azo compounds by the following reaction: 75 h 2 R,C-NH9+2Na0Cl— . 2, 2 Rl V

|3 I3 R2C-N=N-C-R2+2NaCl+2 H2O Rl Rl 25

In the above reaction Ri is alkyl of from 1 to about 6 carbon atoms, optionally substituted with an alkoxy 6 group of 1 to about 4 carbon atoms; R2 is cycloalkyl of from 3 to 6 carbon atoms or alkyl of from 1 to carbon atoms; R3 is a radical selected from the group consisting of CN, COOR, and COOM, where R is an 30 alkyl radical of from 1 to 6 carbon atoms, and M is sodium or potassium; with the proviso that R1 and R2 together contain a total of at least 4 carbon atoms, and with the further proviso that R1 and R2 can be taken together and are alkylene of from 3 to 1 1 carbon atoms. The coupling reaction occurs in the presence of at least 95 percent by volume of a C1 - C2 alcohol. U.S. Patent No. 4,028,345 (Moore, Jr., June 7, 1977) relates to an improved process for the preparation 35 of aliphatic azo compounds.

R2C-NH2+2 M(OCl)r->R2C-N=N-CR2 40 CN CN CN

wherein R1 and R2 are selected from the group consisting of aliphatic hydrocarbon radicals of 1 to 8 45 carbons, optionally substituted with a carboxyl group, a hydroxyl group or an alkoxy group represented by -OR wherein R is an acrylic aliphatic hydrocarbon radical of 1 to 4 carbon atoms; x is the valence of the M ion and a surface active compound selected from the group consisting of an anionic, cationic, nonionic, amphoteric and mixed surface active agents or surfactants. More specifically, this reference relates to a solution process for the preparation of aliphatic azodinitrile compounds by reacting an aqueous hypochlorite 50 with an aminonitrile in the presence of a surface active agent. The above aminonitriles utilized for the preparation of the azo compounds are prepared in a pressure vessel by reacting a ketone with ammonia gas. The vessel is cooled in a dry ice acetone bath. Hydrogen cyanide is then introduced in portions in an amount equivalent to that of the ketone. The reaction vessel is warmed to room temperature and pressurized to 50 psig with ammonia, heated to 40° C and 50 psig for 8 EP 0 436 183 A1

hours and cooled to yield an aminonitrile according to the equation below:

0 R1

RCR'+NH3+HCN ^ RC-NH2 CN w The above references teach the preparation of symmetrical and non-symmetrical azo compounds. In both references, fairly pure aminonitrile is utilized as a starting material for reaction with the metal hypochlorite

R« R' R1 I I I 15 RC-N=N-CR RONH,2 NaOCly* I I I CN CN CN

In the past it was thought that an excess of ammonia was to be avoided in the preparation of the 20 aminonitrile since it might interfere with the coupling reaction:

v r HN=N-CR RC-NH,+NH,2 3 NaOCl>^ 25 I t CN CN

Additionally, water was to be avoided as a solvent in the preparation of the aminonitrile since the water might promote undesirable reverse reactions: 30 R« R' R' I I ' RC-NH2+H2O RC-OH H2Q > RC=O CN 35 CN

Within the present invention the aminonitrile is formed utilizing a solvent; however, the aminonitrile is not recovered. U.S. Patent Nos. 4,684,717 and 4,684,718 (Ashitaka et al, August 4, 1987) provide a process for the 40 preparation of diazocyano acid, which comprises reacting a keto acid or its sodium salt with a cyanogen compound such as sodium cyanide or hydrogen cyanide and a hydrazine in water to form a concentrated aqueous solution of a hydrazo compound, adding acetone and/or water to the concentrated aqueous solution to form a solution of the hydrazo compound, adding chlorine gas to the solution to oxidize the hydrazo compound and form a diazocyano acid, and separating the diazocyano acid from the obtained 45 reaction mixture. U.S. Patent No. 4,831,096 (MacLeay, May 16, 1989) relates to mixtures of azoalkanes of varying thermal stabilities, at least one of which is an unsymmetrical azoalkane (R-N = N-R'). These unsymmetrical azoalkanes are prepared by reacting four equivalents of a mixture of two or more primary alkyl, cycloalkyl or aralkyl amines with one equivalent of sulfuryl chloride in an inert solvent and oxidizing the resulting so mixture of sulfamide products with basic bleach. The unsymmetrical azoalkanes can be separate from the symmetrical azoalkanes by a variety of conventional techniques. The azoalkane mixtures are polymerization initiators for vinyl monomers and curing agents for unsaturated polyester resins.

SUMMARY OF THE INVENTION 55 This invention relates to a process for the preparation of a symmetrical azo compound from a keto acid of the formula EP0 436 183 A1

O II R1CR2COOH

5 wherein Ri is an alkyl group containing from 1 to about 12 carbon atoms and R2 is a direct bond or an with from alkylene group containing from 1 to about 12 carbon atoms. One mole of the keto acid is reacted 1 to about 2 equivalents of M(CN)X in an aqueous medium wherein M is a metal comprising lithium, sodium, potassium, magnesium, or calcium and x is the valence of M and from 1 to about 2 moles of an ammonia metal w source of ammonium hydroxide (28-30 percent) to form an aqueous solution of an aminonitrile carboxylate of the formula

NH2 (R^COO^M (Rlf2 CN

M(CN)X is not volatile and therefore has none of the deleterious properties of HCN which is used in the 20 commercial production of these initiators. It is surprising that an aqueous solution that contains excess ammonium hydroxide can be used to give a good yield of an azodinitrile without serious interference with the coupling reaction. Alternatively, the aminonitrile metal carboxylate can be formed by reacting the keto acid, metal cyanide and ammonia using a lower alcohol as a solvent followed by removal of the alcohol under vacuum. The 25 aminonitrile metal carboxyiate so formed, instead of the carboxylic acid as claimed in previous references, is reacted with from about 1.0 to about 2.5 equivalents of Mi(OCI) per mole of keto acid with the proviso that no alcohol or surface active agent is utilized, wherein Mi is a metal comprising sodium, potassium, or calcium to form an azodinitrile metal carboxylate of the following structure:

R. Rx ("00CR,C-N=N-CR2C00") x2MX+ CN CN 35 when M is lithium, sodium, potassium, magnesium or calcium and X is the valence of M. The excess Mi- (OCI)X is reduced with a reducing agent comprising sodium bisulfite or sodium sulfite and the metal azo carboxylate is neutralized to form an azodinitrile compound of the formula

40 Rl Rl I X I1 HOOCR,C-N=N-CR,COOH 2, | 2 CN CN

Additionally, this invention relates to a process for preparing mixed, symmetrical azonitrile initiators of the formulae:

50 Rl Rl HOOCR,C-N=N-CR,COOH I and 2, , 2 CN CN

55 EP 0 436 183 A1

R- ?< R,C-N=N-CR- II 3, , 3 CN CN

In the above formulae, Ri is an alkyl group containing from 1 to about 12 carbon atoms, R2 is non-existent or an alkylene group containing from 1 to about 12 carbon atoms. R2 may also be a cycloalkylene or alkyl cycloalkylene group containing from 3 to about 12 carbon atoms. R3 and R4 are alkyl groups containing 10 from 1 to about 12 carbon atoms. One of R3 and R4. may be an alkoxy group of from 1 to about 4 carbon atoms. In another embodiment, this invention relates to a process for preparing mixed azonitrile initiators of the formulae:

HOOCR-C— N N — CR-COOH I, 2I I 2 CN CN 20

I* R,C- N = N- CR, II and 25 3 I CN CN

30 R,C-N N- CR2COOH III CN CN

35 In the above formulae, R1 is an alkyl group containing from 1 to about 12 carbon atoms, R2 is non-existent or an alkylene group containing from 1 to about 12 carbon atoms. R2 may also be a cycloalkylene or alkyl cycloalkylene group containing from 3 to about 12 carbon atoms. R3 and R* are alkyl groups containing from 1 to about 12 carbon atoms. One of R3 and R+ may be an alkoxy group of from 1 to about 4 carbon atoms. 40 DETAILED DESCRIPTION OF THE INVENTION

The Keto Acid

45 The keto acids having utility in this invention are of the general formula

RjCR^OOH 50

R1 is an alkyl group containing from 1 to about 12 carbon atoms, preferably from 1 to about 6 carbon atoms and most preferably from 1 to about 3 carbon atoms. Such groups are known to those skilled in the art. Examples include methyl, ethyl, propyl, isopropyl, butyl, isobutyl and t-butyl. 55 R2 is an alkylene group containing from 1 to about 12 carbon atoms and preferably 1 to about 6 carbon atoms or a cycloalkylene group containing from 3 to about 12 carbon atoms. When R2 is not cyclic, R2 most preferably contains from 1 to about 4 carbon atoms. When R2 is cyclic it most preferably contains from about 3 to about 6 carbon atoms. Some examples of R2 cyclic alkylenes are EP 0 436 183 A1

CH- I 2 ,— CH- @ CH-

/CH2. / CH. CH. CHS /CH- a.o and 10 CH — CH • @CH' CH.,

When R2 is not cyclic, examples are methylene, ethylene, propylene, butylene, as well as any branching 15 thereof. The following table lists a few of the many keto acids having utility in this invention. This list is merely illustrative and is not meant to be all-inclusive. A preferred keto acid is levulinic acid.

TABLE I

20 Keto Acids R. Name acid CH3 non-exi stent pyruvic 3-oxobutanoic acid 25 CH3 CH2 levulinic acid CH3 CH2CH2 5-oxohexanoic acid CH3 CH2CH2CH2 6-oxoheptanoic acid CH3 CH2CH2CH2CH2 30 7-oxooctanoic acid CH3 CH2CH2CH2CH2CH2 2-oxobutanoic acid CH3CH2 non-existent 3-oxopentanoic acid CH3CH2 CH2 35 4-oxohexanoic acid CH3CH2 CH2CH2 5-oxoheptanoic acid CH3CH2 CH2CH2CH2 4-oxoheptanoic acid CH3CH2CH2 CH2CH2 40 levulinic acid CH, CH2CH 2 -methyl CH,

45 The Metal Cyanide

One mole of the keto acid is reacted with from about 1 to about 2, preferably 1 to about 1 .5, and most preferably from about 1 to about 1.1 equivalents of a metal cyanide of the formula M(CN)X wherein the 50 metal M comprises lithium, sodium, potassium, magnesium, or calcium and x is the valence of M. An equivalent of M(CN)X is its weight in grams, pounds, etc. divided by its equivalent weight. The equivalent weight of M(CN)X is equal to its molecular weight divided by the valence of x. An equivalent weight of NaCN is 49 (49 molecular weight divided by valence of 1) and 49 grams is one gram-equivalent of NaCN. An equivalent weight of Ca(CN)2 is 46 (92 molecular weight divided by valence of 2) and 46 grams is one 55 gram-equivalent of Ca(CN)2. The reaction of the keto acid with M(CN)X is a reversible addition reaction that strongly favors the right side with very little by-products formed. A preferred metal cyanide is sodium cyanide. EP0 436 183 A1

0 OH / || ^ R1CR2COOH+M(CN) 7^> (^CR^COO) xM 5 CN

In order to convert the cyanohydrin metal carboxylate to an aminonitrile metal carboxylate, 1 to about 2 moles of an of an ammonia source per 0.5-1 moles of keto acid is introduced. 10 OH NH2

(R1CR2COO)XM a^gSia^ (R1CR2COO)XM + H2O | "^ source, \ solvent CN 15 CN

When the ammonia source is ammonium hydroxide (28-30 percent), water is used as a solvent; when the ammonia source is ammonia gas, a lower carbon alcohol is used.

20 The Metal Hypochlorite

The aminonitrile metal carboxylate is converted to the azodinitrile metal carboxylate by action of Mi- (OCI)X in the ratio of from about 1.0 to about 2.5, preferably from about 1.2 to about 2.0, and most preferably from about 1.2 to about 1.5 equivalents of metal hypochlorite per mole of keto acid. Mi 25 comprises sodium, potassium, or calcium and x is the valence of the metal M-i. Sodium is the preferred metal.

Reducing Agent

30 After the azo compound is formed, the excess unreacted Mi(OCI)x is removed for environmental concerns. This is done by utilizing a reducing agent such as sodium bisulfite or sodium sulfite. The reducing agent is added as a 20 percent by weight aqueous solution. Further, no alcohol or surface active agent is utilized. Just enough reducing agent is added to provide a negative test for Kl-starch test paper; i.e., Kl-starch paper is no longer darkened by \z. 35 M1(OC1)X + NaHSO3 ^ M1(C1)X + NaHSO4 or M1(OC1)X + Na2SO3 > Mi(Cl>x + Na2SO4 40

Neutralization Agent

45 Once the metal hypochlorite is reduced, the azodinitrile metal carboxylate is ready to be neutralized to form the azo dicyanocarboxylic acid. The neutralization agent is usually an inorganic acid such as hydrochloric acid, nitric acid or sulfuric acid. The preferred mineral acid is hydrochloric acid. The azodinitrile metal carboxylate is of the following structure

50 Rl Rl (~OOCR2C-N=N-CR2COO~) X2MX+ CN CN 55

where M is lithium, sodium, potassium, magnesium, or calcium and X is the valence of M. Acidifying the above azodinitrile metal carboxylate yields the azodinitrile of the structure:

8 EP0 436 183 A1

Rl Rl I1 I1 HOOCR, C-N=N-CR, COOH 2I I 2 CN CN 5

The compositions prepared by the process of this invention are formed by preparing a mixture of metal cyanide, ammonia source and solvent. To this mixture is added a keto acid to form the aminonitrile metal carboxylate, 10 f» M(OOCR2C-NH2)X CN 75

The order of addition can be varied. It may be carried out as above or the metal cyanide can be suspended or dissolved in solvent, the keto acid added to generate a cyanohydrin followed by the addition of the ammonia source. 20

0 OH — » M (CN) x+R1CR2COOH (R1CR2COO) XM CN

ammonia ^ M(OOCR2C-NH2). 30 ^source, I solvent CN

Or the ammonium salt of the acid can be formed first followed by the addition of metal cyanide. 35

O O // II _ + ammonia+R1CR2C00H — ^ R1CR2COO NH4 then source 40

o Ri ' II + R.CR,COO~NHA Mfon > M(OOCR2C-NH2) < CN

The preferred method is to mix metal cyanide and ammonium hydroxide in water followed by additions of the keto acid. The advantages are (a) the pH is always greater than 8, there is no danger of HCN so escaping and (b) all intermediates remain in solutions therefore, no solidification can occur. If excess ammonia is present after the formation of the aminonitrile metal carboxylate, the overall yield of the azodinitrile metal carboxylate is not diminished but rather more metal hypochlorite will have to be used to convert the amino metal carboxylate to the azodinitrile metal carboxylate. The solvent can be water or a lower carbon alcohol such as methanol or ethanol, preferably methanol. If a lower carbon alcohol is 55 used as the solvent, it has to be removed and when this is done, the aminonitrile metal carboxylate is obtained as an oil which tends to solidify. If the lower carbon alcohol is not removed before the addition of the metal hypochlorite, lower yields of azodinitriles are obtained. An advantage of utilizing water as the solvent is that the processing is easier due to the fact that the aminonitrile metal carboxylate does not have EP 0 436 183 A1

to be isolated. The molar ratio of keto acid:ammonia source is from about 0.5-1:1-2, preferably from 1:1-1.5 and most preferably 1:1-1.1. After reaction of the ammonia source, nitrogen is bubbled through the reaction mixture to remove excess ammonia source. The equivalent ratio of amino nitrile metal carboxylate: Mi (OCI)X is from 5 about 1:1.0-2.75 preferably 1:1.3-2.0 and most preferably 1:1.5-1.8. The excess Mi(OCI)x is neutralized with up to about a 100 percent excess of NaHSO3 or Na2SO3, preferably a 0-10 percent excess and most preferably a 0-2 percent excess of reducing agent. The reaction temperature for any of the intermediates is from about 0° C to about 60° C preferably from about 25 to about 50° C and most preferably from about 30 to about 40 °C. The reaction temperature for the coupling of aminonitrile metal carboxylate to form the 10 azodinitrile metal carboxylate is from about -15 to about 35° C, preferably from about 0 to about 25° C and most preferably from about 0 to about 10° C. The azodinitrile produced by the process of this invention can be used as a polymerization initiator in emulsion, dispersion and solution polymerization systems. Polymerization involving vinyl chloride, methyl methacrylate, and butadiene-styrene are merely examples of such systems in industry that would benefit 75 from the use of such initiators. If an azodinitrile containing a low salt content is desired, the azodinitrile can be washed with water either before or after isolation. The following examples are illustrative of the preparation of azodinitriles. Unless otherwise indicated, all parts and percentages are by weight. 20 EXAMPLE 1

Charged to a 50 milliliter, three-neck round bottom flask fitted with a thermometer and magnetic stirrer was 5.15 parts (0.105 moles) sodium cyanide, 6 parts water and 6.4 parts (0.105 moles) 28 percent 25 ammonium hydroxide in water. The contents were stirred and cooled in a water bath. At 25 °C 11.6 parts (0.1 mole) levulinic acid dissolved in 7 parts water was added drop-wise. After completion of the levulinic acid addition, the water bath was removed and the temperature was raised to 35° C. To a 500 milliliter jacketed flask with a thermometer and mechanical stirrer was added 130 parts of a 13 percent aqueous solution of sodium hypochlorite and the temperature was lowered to below minus 5 C. 30 The contents of the 50 milliliter flask were added drop-wise over two hours at a temperature range of between minus 9°C to minus 5°C. After the addition was complete, 30 parts of a 19 percent aqueous solution of sodium bisulfite were added to reduce the excess sodium hypochlorite. The pH was about 10. An additional 3.2 parts sodium bisulfite solution was added and the resulting pH was 7. Ten parts concentrated hydrochloric acid were added to convert the sodium salt to the free carboxylic acid. The pH 35 was 2. The contents were filtered and the solid product water-washed to obtain 1 1 .2 parts of a white solid having the following structure:

CH, CH,

40 HOOCCH2CH2C-N=N-CCH2CH2HOOCCH2CH2C-N=N-CCH2CH2COOH CN CN

45 EXAMPLE 2

Added to a one liter three-neck round bottom flask with thermometer and mechanical stirrer was 116 parts (1 mole) levulinic acid and 400 parts methanol. The contents were cooled to 20 °C and 51.5 parts (1 .05 moles) sodium cyanide were added in portions. After all the sodium cyanide was added, ammonia gas 50 was bubbled below the surface over a two hour period while maintaining the temperature at 20° C. The contents were stirred at 25 °C for about three hours and filtered and the solid product was rinsed with isopropyl alcohol. About 150.1 parts of a sodium salt of an amino nitrile was obtained. To a two liter three-neck round bottom flask with thermometer and mechanical stirrer is added 860 parts of a 13 percent aqueous solution of sodium hypochlorite and the temperature is lowered to below minus 55 5° C. About 150 parts of the sodium salt of the amino nitrile prepared above is dissolved in about 300 parts water and are added drop-wise over a three hour period while maintaining the temperature at between minus 10° to minus 5°C. After this addition is complete, 290 parts of a 19 percent aqueous solution of sodium bisulfite is added to reduce the excess sodium hypochlorite. About 500 parts concentrated HCI is

10 EP 0 436 183 A1

added to convert the sodium salt to the free carboxylic acid. The contents are filtered to give a product having the same structure as in Example 1 .

EXAMPLE 3 5 Charged to a one liter three-neck round bottom flask with thermometer and mechanical stirrer are 51 .5 ammonium parts (1.05 moles) sodium cyanide, 75 parts water and 64 parts (1.05 moles) 28 percent 27° hydroxide in water. The contents are stirred and cooled in a water bath. At C, 130 parts (1 mole) 5- oxohexanoic acid is added in a slow stream. After the 5-oxohexanoic acid addition is complete, the water 10 bath is removed and the temperature is raised to 37° C. To a two liter jacketed flask with a thermometer and a mechanical stirrer is added 573 parts^of a 13 C. The percent aqueous solution of potassium hypochlorite and the temperature is lowered to about -5 contents of the one liter flask are added drop-wise at a temperature range of between -10 to -5 C. After the addition is complete, 550 parts of a 19 percent aqueous solution of sodium bisulfite are added to reduce the 75 excess sodium hypochlorite. The pH is at about 10. Nine hundred parts concentrated HCI is added to convert the sodium salt to the free carboxylic acid. The contents are filtered to give a product having the following structure:

20 / 3 j 3 HOOCCH2CH2CH2C-N=N-CCH2CH2CH2COOH CN CN

25 EXAMPLE 4

Charged to a 50-ml, 3-neck, round-bottom flask with thermometer and magnetic stirrer, was 5.15 parts (0.105 moles) sodium cyanide, 17 parts (0.105 moles) 28 percent ammonium Jiydroxide in water, and 2 35° 30 parts water. The closed system was cooled in a water bath and at about C 11.6 parts (0.1 moles) levulinic acid was added drop-wise. The reaction temperature was maintained at between about 35-40 C for about 2 hours. The contents were cooled to 25 °C and nitrogen was bubbled below the surface for 1 hour to remove excess ammonia. To a 300-ml jacketed flask with thermometer and mechanical stirrer was added 74.5 parts (0.14 moles) 35 of the 14.5 percent by weight aqueous solution of sodium hypochlorite and the contents were cooled to about 0°C. The contents of the 50-ml flask were then added drop-wise at between about 0-5 C over 52 minutes. After the addition was complete, the contents were stirred for about 1 .5 hours at about 0 C. About Kl 5.9 parts of a 20 percent aqueous sodium sulfite solution was added until there was no reaction with 12.5 ml concentrated paper. The pH of the solution was 12. About 40 g water was added followed by ml 40 hydrochloric acid and the pH was lowered to about 1. The contents were filtered and rinsed with 30 portions of water three times to give a product having the same structure as in Example 1 . In another embodiment, the invention relates to the preparation of mixed, symmetrical azonitrile initiators which when prepared by the process of the present invention are less expensive due to the utilization of acetone or other lower alkyl ketones and have a lower viscosity since the mixed, symmetrical 45 azonitrile initiator has terminal end groups of either carboxyl or alkyl. The various important properties of mixed, symmetrical azonitrile initiators are physical state, solubility, volatility, toxicity, thermal stability and initiator efficiency and these properties are dependent upon the initiators nature of the end groups carboxyl and alky. The thermal stability of mixed, symmetrical azonitrile is intermediate between the stabilities of symmetrical azonitrile initiators HOOCR-N = N-RCOOH or R-N = N- 50 R and the unsymmetrical azonitrile initiator HOOC-N = N-R. Many of the mixed, symmetrical azonitrile initiators have unique thermal and initiator properties which cannot be duplicated by the purely symmetrical thermal or purely unsymmetrical azonitrile initiators. Mixtures of symmetrical azonitrile initiators have unique and initiator properties that may extend over a wide temperature range depending upon the end groups. It is known in the art that a symmetrical azonitrile initiator of the formula R-N = N-R made from an 55 aminonitrile utilizing about 0.25 percent of a surfactant is obtained in a low yield. Mixed, symmetrical azonitrile initiators of the formula HOOCR-N = N-RCOOH and R-N = N-R made from an aminonitrile metal carboxylate and aminonitrile utilizing about 0.20 percent surfactant is obtained in a high yield. The following reactants are utilized in the preparation of mixed, symmetrical azonitrile initiators: keto

11 EP 0 436 183 A1

acid, metal cyanide, ammonia source, metal hypochloride, amino nitrile, surfactant, reducing agent and neutralization agent.

The Keto Acid 5 The description of the keto acid is the same as set forth hereinabove.

The Metal Cyanide

w The description of the metal cyanide is the same as set forth hereinabove.

Ammonia Source

As examples of the ammonia source, there can be mentioned both gaseous ammonia and concentrated 75 ammonium hydroxide (28-30%).

OH NH, on (R^CR^COO)^ ammonia ^ (RjCR2COO)xM + H2O I^ source , solvent CN CN

25 When the ammonia source is concentrated ammonium hydroxide, water is used as a solvent; when the ammonia source is ammonia gas, a lower carbon alcohol is used.

Aminonitrile

30 Aminonitriles having utility in this invention are of the general formula

NH,

R3CR4 35 CN

R3 and FW are alkyl groups independently containing from 1 to about 12 carbon atoms, preferably from 1 to about 6 carbon atoms and most preferably from 1 to about 4 carbon atoms. The alkyl groups may be 40 branched or straight chained. One of the groups R3 or FU may also be an alkoxy group containing from 1 to about 4 carbon atoms. Preferred aminonitriles are acetone aminonitrile wherein R3 and R4 are methyl groups and 2-butanone aminonitrile wherein R3 is methyl and R* is an ethyl group.

The Metal Hypochlorite 45 The aminonitrile metal carboxylate and aminonitrile are converted to the azonitrile metal carboxylate and azonitrile respectively by action of aqueous Mi(OCI)x. Mi comprises sodium, potassium, or calcium and x is the valence of the metal M. Sodium is the preferred metal. The concentration of Mi(OCI)x in water is from about 2 to about 20 percent, preferably from about 5 to about 17 percent, and most preferably from 50 about 9 to about 16 percent. After the aminonitrile metal carboxylate is formed, coupling within the aminonitrile metal carboxylate is effected by the metal hypochlorite. An aminonitrile is added and the remaining Mi (OCI)X causes coupling within the aminonitrile. This coupling takes place in the presence of a surfactant.

55 The Surfactant

The surfactant compounds of the present invention are defined as any compound or mixture of compounds that affects the surface tension when mixed with water and is not adversely affected in its

12 EP 0 436 183 A1

properties if it reacts with the hypochlorite, aminonitrile metal carboxylate, aminonitrile or final product of the present invention. The inclusion of a surfactant in the process of coupling an aminonitrile metal carboxylate to another aminonitrile metal carboxylate or an aminonitrile to another aminonitrile to give mixed, symmetrical azonitrile 5 initiators with a metal hypochlorite enables the reaction to proceed in an aqueous medium. Surfactants useful in the process of the present invention may be a single surfactant or mixtures thereof. Cationic surfactants are preferred. Cationic surfactants include various types of nitrogen containing compounds such as fatty alkyl amines and their salts and quaternary ammonium compounds or more specifically tetraalkyl ammonium com- w pounds. Tetraalkyl ammonium halides are considered to be the most important type of cationic surfactants. The tetraalkyl ammonium chlorides or bromides are preferred. The tetraalkyl ammonium chlorides are considered the most preferred cationic surfactant. What is meant by tetraalkyl ammonium in the compounds described herein is that they contain a nitrogen atom to which four separate carbon atoms are attached. Representative examples of tetraalkyl ammonium surfactants of the present invention include: 75

13 EP 0 436 183 A1

Compound Trade Name Manufacture Disoya dimethyl Arquad 25-751 Armak Co. ammonium chloride

Ditallow Imidazolinium Alkaquat T Alkaril Chem. quaternary salt 10

Cetyl trimethyl Retarder LAN DuPont Co. ammonium bromide 75 Quaternized polyoxy- Ethoquad C/25 Armak Co. ethylene cocoamine Arquad T-50 Armak Co. 20 Tallow trimethyl ammonium chloride

Tetradecyl trimethyl Armak Co. 25 ammonium chloride

Dodecyl trimethyl Arquad 12-50 Armak Co. 30 ammonium chloride

Hexadecyl trimethyl Arquad 16-50 Armak Co.

35 ammonium chloride

Octadecyl trimethyl Arquad 15-50 Armak Co. ammonium chloride 40

175 percent aqueous solution 225 percent aqueous solution 45 350 percent aqueous solution A preferred cationic surfactant is Arquad 16-50.

50 Within the process of the present invention, the surfactant is present in a catalytic amount of from about 0.05 percent active to no more than about 0.20 percent active, preferably from about 0.08 percent active up to about 0.20 percent active and most preferably from about 0.12 percent active up to about 0.20 percent active by weight based on the total weight of aminonitrile metal carboxylate and aminonitrile. By active surfactant, it is meant the weight of the surfactant less any diluent according to the below equations: 55 weight active surfactant = (weight of surfactant)(1 00%-% diluent). If a surfactant is 75 percent aqueous and 0.1 g is employed, then: weight active surfactant = (0.1 g) (100%-75%) = 0.0025 g.

14 EP 0 436 183 A1

Reducing Agent

After the azonitrile metal carboxylate and azonitrile are formed, the excess unreacted Mi(0CI)x is removed for environmental concerns. This is done by utilizing a reducing agent such as sodium bisulfite or Just 5 sodium sulfite. The reducing agent is added as a 20 percent by weight aqueous solution. enough reducing agent is added to provide a negative test for Kl-starch test paper; i.e., Kl-starch paper is no longer darkened by I2.

M1(OC1)X + NaHSO3 > M1(C1)X + NaHSO4 10 or + M1(OC1)X + Na2SO3 > M1(C1)X Na2S04

75 Neutralization Agent

Once the metal hypochlorite is reduced, the azonitrile metal carboxylate is ready to be neutralized to form the azonitrile acid (I) within the mixed, symmetrical azonitrile initiator. The neutralization agent is mineral acid is 20 usually an inorganic acid such as hydrochloric acid, nitric acid or sulfuric acid. The preferred hydrochloric acid. The azonitrile metal carboxylate is of the following structure

/<@ ?' III 25 (~OOCR,C-N=N-CR,COO~)("OOCR2C-N=N-CR2COO")3t2Mx* ,2MX+ CN CN

where M is lithium, sodium, potassium, magnesium, or calcium and x is the valence of M. Acidifying the 30 above azonitrile metal carboxylate yields the azonitrile initiator of the structure:

Rl Rl HOOCR2C-N=N-CR2COOH I 35 CN CN

The compositions prepared by the process of the present invention are formed by preparing a mixture of metal cyanide, ammonia source and solvent. To this mixture is added a keto acid to form the aminonitrile 40 metal carboxylate,

M(OOCR2-C-NH2)X \ CN

The order of addition can be varied. It may be carried out as above or the metal cyanide can be suspended the or dissolved in solvent, the keto acid added to generate a cyanohydrin followed by the addition of 50 ammonia source.

15 EP 0 436 183 A1

0 OH

M(CN) + R1CR2COOH > (R^RjCOO) xM < CN 5

ammonia M ) ^ (OOCR2C-NH2 x Source , 10 solvent CN

Or the ammonium salt of the acid can be formed first followed by the addition of metal cyanide.

75 0 0 II II . ammonia + R^RjCOOH > RjCRjCOO'NH^ then source 0 Ri II MfCN)A> I1 R1CR2COO~NH4+ < M(OOCR2C-NH2)X

CN 25 The preferred method is to mix metal cyanide and ammonium hydroxide in water followed by additions of the keto acid. The advantages are (a) the pH is always greater than 8, therefore no danger of HCN escaping and (b) all intermediates remain in solutions - no solidification can occur. If excess ammonia is present after the formation of the aminonitrile metal carboxylate, the overall yield 30 of the azonitrile initiator (I) is not diminished but rather more metal hypochlorite will have to be used to convert the aminonitrile metal carboxylate to the azonitrile metal carboxylate. Excess ammonia is removed by passing an inert gas such as nitrogen or argon through the reaction medium. The solvent can be water or a lower carbon alcohol such as methanol or ethanol, preferably methanol. If a lower carbon alcohol is used as the solvent, it has to be removed and when this is done, the aminonitrile metal carboxylate is 35 obtained as an oil which tends to solidify. If the lower carbon alcohol is not removed before the addition of the metal hypochlorite, lower yields of azonitrile initiators are obtained. An advantage of utilizing water as the solvent is that the processing is easier due to the fact that the aminonitrile metal carboxylate does not have to be isolated. The molar ratio of keto acid: ammonia source is from about 0.5-1:1-2, preferably from 1:1-1.5 and most 40 preferably 1:1-1.1. After reaction of the ammonia source, nitrogen is bubbled through the reaction mixture to remove excess ammonia source. Once the aminonitrile metal carboxylate solution is formed, Mi(0CI)x and a surfactant are added followed by the dropwise addition of an aminonitrile such as acetone aminonitrile. Alternatively, the Mi (OCI)X and surfactant can be added to the aminonitrile and the aminonitrile metal carboxylate can be added 45 dropwise to the aminonitrile solution. The molar ratio of aminonitrile metal carboxylate:aminonitrile is from about 0.5-10:1, preferably from about 0.5-5:1 and most preferably from about 0.9-1.1:1. The equivalent weight ratio of the sum of the aminonitrile metal carboxylate and aminonitrile: Mi (OCI)X is from about 1:1.0-2.75 preferably 1:1.1-2.0 and most preferably 1:1.2-1.5. The excess Mi(OCI)x is neutralized with up to about a 100 percent excess of NaHSO3 or Na2SO3, preferably a 0-10 percent excess so and most preferably a 0-2 percent excess of reducing agent. The reaction temperature for any of the intermediates is from about 0°C to about 60 °C preferably from about 25 to about 50 °C and most preferably from about 30 to about 40° C. The reaction temperature for the coupling of aminonitrile metal carboxylate and aminonitrile to form the mixed symmetrical azonitrile initiators is from about -15 to about ° ° ° 35 C, preferably from about 0 to about 25 C and most preferably from about 0 to about 1 0 C. 55 The mixed, symmetrical azonitriles produced by the process of this invention can be used as a polymerization initiator in emulsion dispersion and solution polymerization systems. Polymerization involving vinyl chloride, methyl methacrylate, and butadiene-styrene are merely examples of such systems in industry that would benefit from the use of such initiators.

16 EP0 436 183 A1

If a mixed, symmetrical azonitrile initiator containing a low salt content is desired, the azonitrile initiator can be washed with water either before or after isolation. The following examples are illustrative of the preparation of azonitrile initiators. Unless otherwise indicated, all parts and percentages are by weight. 5 EXAMPLE 5

Charged to a 50 milliliter, three-neck round bottom flask fitted with a thermometer and magnetic stirrer was 5.15 parts (0.105 moles) sodium cyanide, 4 parts water and 7.0 parts (0:115 moles) 28 percent w ammonium hydroxide in water. The contents were stirred and cooled in an ice water bath. At between 0- 5° C 11.6 parts (0.1 mole) levulinic acid dissolved in 7 parts water was added drop-wise. After completion of the levulinic acid addition, the water bath was removed and the temperature was raised to 35 C. Nitrogen was bubbled through the solution to remove excess ammonia. To a 300 milliliter jacketed flask with a thermometer and mechanical stirrer was added 128.4 parts of a vial 75 14 percent aqueous solution of sodium hypochlorite and 0.1 part of Arquad 16/50 surfactant. The containing the surfactant was rinsed with 1 part water, added to the reaction vessel, and the temperature was lowered to 0°C. The contents of the 50 milliliter flask were added dropwise over two hours at a temperature range of between 0° C to 5° C. To the contents were added 7.8 parts of a 20 percent aqueous solution of sodium sulfite to reduce the excess sodium hypochlorite. The pH was about 12 and there was no 20 reaction with Kl paper. About 15 parts concentrated hydrochloric acid were added to convert the sodium salt to the free carboxylic acid. The pH was about 1 . The contents were filtered and the solid product water- washed to obtain 17.7 parts of a white solid that is a mixture of the following structures:

25 <~H3 ^H3 HOOCCH2CH2ON=N-CCH2CH2COOH and CN CN CH, CH, 30 I •* I H,CC-N=N-CCH, 3 , ,3 CN CN

35 An HNMR in MeOD showed that the white solid is approximately a 1:1 by weight mixture of the above structures.

EXAMPLE 6

40 The aminonitrile of sodium levulinate in water solution was prepared in the same manner and in the same amount as in Example 1 . To a 300 milliliter jacketed flask with a thermometer and mechanical stirrer was added 128.4 parts of a The vial 14 percent aqueous solution of sodium hypochlorite and 0.1 part of Arquad 16/50 surfactant. containing the surfactant was rinsed with 1 part water, added to the reaction vessel, and the temperature 45 was lowered to 0°C and 9.8 parts (0.1 mole) 2-amino-2-methylbutyonitrile was added dropwise at a temperature of between 0 to 5°C. The aminonitrile addition took 30 minutes. The contents were permitted to stir for 5 minutes after completion of the addition. The aminonitrile of sodium levulinate solution was added dropwise over 45 minutes at a temperature range of between 0 and 5° C about 15 minutes. After the addition was complete, 50 parts of a 20 percent aqueous solution of sodium sulfite were added to reduce so the excess sodium hypochlorite. Concentrated hydrochloric acid was added to convert the sodium salt to the free carboxylic acid. The pH was between 1 and 2. The contents were filtered and the solid product water-washed to obtain 18.6 parts of a white solid having the following structure:

17 EP 0 436 183 A1

CEL CH,3 3 \ \ H00CCHoCH,C-N=N-CCH,CH,C00H and 2 2/ i 2 2 5 CN CN CH, CH, ,3 ,3 CH3CH2C-N=N-CCH2CH3 CN CN 10

In still another embodiment of the present invention, mixed azonitrile initiators are prepared utilizing hydrazine and other compounds. Such mixed azonitrile initiators are less expensive due to the utilization of acetone as a ketone, have a lower viscosity than diazocyano acids since the mixed azonitrile initiator has 75 terminal end groups of either carboxyl or alkyl abd are prepared in an acetone solution with said acetone solution being used directly for the polymerization without isolation of the mixed azonitrile initiator. The various important properties of mixed azonitrile initiators are physical state, solubility, volatility, toxicity, thermal stability and initiator efficiency and these properties are dependent upon the nature of the end groups carboxyl and alkyl. The thermal stability of mixed azonitrile initiators is intermediate between the 20 stabilities of symmetrical azonitrile initiators HOOCR-N = N-RCOOH or R-N = N-R and the unsymmetrical azonitrile initiator HOOCR-N = N-R. Many of the mixed azonitrile initiators have unique thermal and initiator properties which cannot be duplicated by the symmetrical or unsymmetrical azonitrile initiators. Mixtures of unsymmetrical and symmetrical or unsymmetrical azonitrile initiators have unique thermal and initiator properties that may extend over a wide temperature range depending upon the end groups and the ratio of 25 symmetrical:unsymmetrical azonitrile initiators. The azonitrile initiators have the chemical moiety

30 -C-N=N-C- I I CN CN

35 and the -N = N- moiety is indicative of an azo compound. In the practice of this invention, the azo moiety is generated from a hydrazo moiety

H H

-N-N-

by the oxidative effect of the chlorine gas. This invention is directed to three different processes for the preparation of the hydrazo moiety. 45 The three processes to prepare the hydrazo moiety all utilize a keto acid, a cyanohydrin, a metal cyanide, and a hydrazine source. The cyanohydrin may be used as a starting material or it may be formed in situ.

The Keto Acid 50 The keto acids are the same as described hereinabove and thus are hereby fully incorporated.

The Cyanohydrin

55 Cyanohydrins having utility in this invention are of the general formula

18 EP 0 436 183 A1

R3CR4 CN

R3 and FU are alkyl groups independently containing from 1 to about 12 carbon atoms, preferably from 1 to about 6 carbon atoms and most preferably from 1 to about 4 carbon atoms. The alkyl groups may be branched or straight chained. One of the groups R3 or R* may also be an alkoxy group containing from 1 to 10 about 4 carbon atoms. A preferred cyanohydrin is acetone cyanohydrin. The cyanohydrin may be formed in situ by the reaction of CN~ on the carbonyl moiety,

75 of a ketone

O OH

R3CR4 + CN H^ R3CR4 CN

A preferred ketone is acetone where R3 and R+ are methyl groups. 25 The Metal Cyanide

One mole of the keto acid is reacted with from about 1 to about 2 equivalents of a metal cyanide of the formula M(CN)X and a catalytic amount of hydrochloric acid wherein the metal M comprises lithium, sodium, 30 potassium, magnesium, or calcium and x is the valence of M. The reaction of the keto acid with M(CN)X to form a cyanohydrin metal carboxylate is an addition reaction with no by-products formed. A preferred metal cyanide is sodium cyanide.

Hydrazine Source 35 As examples of the hydrazine source, there can be mentioned both hydrazine and hydrazine hydrate. Preferred is hydrazine hydrate. Depending upon the order of addition, at least three different processes exist for the formation of the hydrazo moiety -NH-NH- . 40 In one process, a keto acid is reacted with M(CN)X in the presence of a slight amount of concentrated hydrochloric acid to form a cyanohydrin metal carboxylate.

0 OH M(CN)r->(R,CR.,COO-> Mx+ 45 R.CR.COOHRjCRjCOOH + M(CN)r^(R1CR2COO">xM3C+ CN

After formation of the cyanohydrin metal carboxylate, a cyanohydrin is added followed by the hydrazine to 50 give rise to the three hydrazo formulae:

19 EP 0 436 183 A1

OH OH

(I^CRjCOO^M + R3CR4 + HjNNH^-* (IV), (V), and (VI) CN CN

R. H H R. / x I I I1 10 (-OOCR-C-N— N — CR,COO^") ' ™x+2M* IV, 2| I z x CN CN

15 I4 I I I4 R-C-N-N-CR, V and 3, | 3 CN CN

20 RA H H R. I4 I \ I1 -> (R,C — N — N- CR-COO ' MMx+ VI 3I I 2 x CN CN 25

For every mole of keto acid used, 1 to 2, preferably 1 to 1 .5 and most preferably 1 to 1 .1 equivalents of M(CN)X is used; 0.1 to 10.0, preferably 0.5 to 2.0 and most preferably 0.8 to 1.5 moles of cyanohydrin is employed, and 0.4 to 0.75, preferably 0.4 to 0.6 and most preferably 0.45 to 0.55 moles of a hydrazine 30 source is used. Acetone is added to the mixed hydrazo intermediates at a molar ratio of cyanohydrin plus keto acid: acetone of from about 1.5 to about 1:30, preferably from about 1:7 to about 1:12 and most preferably from about 1:8 to about 1:10 moles. After the acetone is added, chlorine gas is bubbled into the hydrazo intermediates to oxidize the hydrazo intermediates to azo compounds. HCI is generated which reacts with 35 the metal carboxylate to give the free carboxylic acid thus forming the mixed azonitrile initiators of Formulae I, II and III. In another process, a keto acid, ketone, metal cyanide and catalytic amount of hydrochloric acid are reacted together and the cyanohydrin is formed in situ from the ketone.

40 OO II I + + R,CR,COOH12 R,CR. M(CN)_x —>

OH OH 45 I / (R.CR-COO) M + R,CR. CN CN

50 The products formed are then reacted with hydrazine hydrate to form the mixed hydrazo intermediates. Acetone is added and the mixed hydrazo intermediates are further reacted with chlorine gas as per the previous process to obtained the mixed azonitrile initiators of formulae I, II, and III. For every mole of keto acid used, from about 0.1 to about 10, preferably from about 0.5 to about 2.0 and most preferably from about 0.8 to about 1 .5 moles of ketone is employed. The ratios of the other various reactants are as per the 55 previous process. In still another process, the keto acid is added to an aqueous solution of a metal cyanide and hydrazine hydrate followed by a ketone and HCI gas.

20 EP 0 436 183 A1

// R3 CR4 + R.CR-COOH + M(CN) > > H,NNH,2 2 12 x s HC1

R. H H R. II I I (-OOCR2C-N-N~CR2COO")X2MX+ IV, ™ CN CN +

R4 H H R4 l4 I i I4 V and 75 R-C— N-N— CR- CN CN

R4 H H Rj 20 I I I I N- CR,COO")MX+ VI (R,C- N- 2 3 , CN CN

25 Acetone, as a solvent, is added and the mixed hydrazo intermediates are further reacted with chlorine gas and III. The ratios of as per the previous process to obtained the mixed azonitrile initiators of formulae I, II, the various reactants are as per the previous processes. The following examples are illustrative of the preparation of mixed azonitrile initiators. Unless otherwise 30 indicated, all parts and percentages are by weight.

EXAMPLE 7

Added to a one liter three-neck round bottom flask with addition funnel thermometer and mechanical 35 stirrer was 20.3 parts (0.41 moles) NaCN in 40 parts water. Stirring was begun and 46.4 parts (0.40 moles) levulinic acid in 40 parts water was added. About 2.8 parts concentrated HCI was added followed by 10 and parts water. An additional 20.3 parts NaCN followed by 10 parts rinse water for the funnel was added a 20° temperature maintained at between 20°-30°C for 30 minutes. At to 30 °C, 34.7 parts (0.4 moles) 30° acetone cyanohydrin was added followed by 5 parts water. About 10 to 15 minutes later at less than C, 15 40 23 parts (0.39 moles) hydrazine hydrate was added and the funnel was rinsed with 20 parts water. After minutes, the pH was adjusted to 6 with the addition of hydrochloric acid and the contents were heated to 35° C and held there for two hours. The contents were cooled to 5° -10° C and 416 parts acetone were added. The formed mixed hydrazo intermediates were then oxidized by bubbling in 30.2 parts chlorine. The pH prior to chlorine addition was 7.56 and 3.86 at the end of the addition. The pH was kept between 3-7.56 The maximum 45 by adding 34 parts of 50 percent aqueous sodium hydroxide during the chlorine addition. temperature during oxidation was 15° C. Two layers were formed and separated. The upper acetone solution was concentrated and vacuum dried to obtain 137.3 parts solid. Nitrogen analysis indicated that this solid contained 58.6 percent azodinitriles which related to 90.6 percent yield. Note: The upper acetone solution can be used directly for polymerization. The purpose of the work-up was to determine the percent so yield.

EXAMPLE 8

Added to a one liter three-neck round bottom flask with addition funnel thermometer and mechanical The 55 stirrer were 46.4 parts (0.4 moles) levulinic acid, 23.2 parts (0.4 moles) acetone and 40 parts water. temperature was lowered to 5°-10°C and 5.6 parts concentrated HCI was added followed by 20 parts water. About 40.5 parts (0.83 moles) NaCN in 80 parts water was added dropwise at between 5 -10 C and the funnel was rinsed with 20 parts water. At 10° C 40.6 parts concentrated HCI was added and the

21 EP 0 436 183 A1

contents were stirred at 5°-10°C for 20 minutes. The contents were then heated to 30 °C and 23 parts (0.39 moles) hydrazine hydrate was charged followed by rinsing the funnel with 10 parts water. The contents were stirred for 15 minutes and the pH was 6. The contents were kept at 30°-35°C for an additional one hour and then the temperature was lowered to 5°-10°C. About 416 parts acetone was 5 charged and 30 parts chlorine gas was charged below the surface over 1 hour and 40 minutes. During the chlorination the pH went to 0 and was adjusted to about 6 using 26.5 parts of 50 percent aqueous sodium hydroxide solution. After the oxidation was complete, the pH was adjusted to 3.74 with 6.5 parts 50 percent aqueous sodium hydroxide solution. Two layers were formed and separated. The upper acetone solution was concentrated and vacuum dried to obtain 145 parts white semi-solid. Under nitrogen analysis, a sample w of the product was found to contain 45.6 percent azodinitriles which related to a 74.5 percent yield.

EXAMPLE 9

Added to a one liter three-neck round bottom flask with addition funnel, thermometer, and mechanical 75 stirrer were 58.5 parts (0.5 moles) levulinic acid, 17.4 parts (0.3 moles) acetone and 80 parts water. Stirring was begun and 5.6 parts concentrated HCI was added and the funnel was rinsed with 20 parts water. At between 20°-30°C, 40.5 parts (0.83 moles) NaCN in 80 parts water was added dropwise and the funnel was rinsed with 20 parts water. Stirring was continued for 20 minutes at which time 23 parts (0.39 moles) hydrazine hydrate was added at 30° C. The funnel was rinsed with 20 parts water. Stirring was continued for 20 an additional 15 minutes and the pH was adjusted to 6 with about 30 parts concentrated HCI. The contents were stirred for 1.5 hours at 35° C and the temperature was lowered to 5° -10° C. About 416 parts acetone was added dropwise at 5° -10° C. About 29.9 parts chlorine gas was blown below the surface over 1.5 hours with the temperature between 5°-10°C. The pH was adjusted to 4 by the addition of concentrated hydrochloric acid. Two layers were formed and separated. The upper acetone solution was washed with 50 25 ml saturated sodium chloride solution and an extra 19 ml aqueous layer was obtained. The acetone layer was concentrated and vacuum dried at below 35° C to obtain 110 parts semi-solid. Under nitrogen analysis, a sample of the product was found to contain 52.3 percent mixed azodinitriles which related to a 75.1 percent yield.

30 EXAMPLE 10

Added to a one liter three-neck round bottom flask with addition funnel, thermometer, and mechanical stirrer were 40.5 parts (0.83 moles) NaCN in 80 parts water. The contents were cooled to 20 °C and 23 parts (0.39 moles) hydrazine hydrate were added followed by 40.6 parts (0.4 moles) levulinic acid and the ° 35 funnel rinsed each time with 5 parts water. At 20 C, 23.3 parts (0.4 moles) acetone and 41 .5 parts concentrated HCI were both added dropwise. About 20 minutes after addition of HCI, the pH was about 7. The contents were heated to 35° C and held there 1.5 hours and then cooled to 5° -10° C. About 416 parts acetone were added dropwise and chlorine gas was blown below the surface to oxidize the hydrazo intermediate. The pH dropped to 0.7 and was adjusted to 3.1 using 31 .6 parts 50 percent aqueous sodium 40 hydroxide solution. Two layers were formed and separated. The upper acetone solution was concentrated and vacuum dried to obtain 138.7 parts crude semi-solid. Nitrogen analysis showed the sample to contain 56.5 percent azodinitriles which related to an 88 percent yield. While in accordance with the Patent Statutes, the best mode and preferred embodiment has been set forth, the scope of the invention is not limited thereto, but rather by the scope of the attached claims. 45 Claims

1 . A process for the preparation of symmetrical azo compounds, comprising, reacting a keto acid 50

R1CR2COOH

55 wherein Ri is an alkyl group containing from 1 to about 12 carbon atoms, and R2 is a direct bond, or an alkylene group containing from 1 to about 1 2 carbon atoms, or a cycloalkylene group containing from about 3 to about 1 2 carbon atoms

22 EP0 436 183 A1

with from 1 to about 2 equivalents of M(CN)X per mole of keto acid wherein M is a metal comprising lithium, sodium, potassium, magnesium, or calcium and x is the valence of M and an ammonia source in a molar ratio of keto acid:ammonia source of from about 1:1-4 in the presence of a solvent to form an aminonitrile metal carboxylate of the formula

NH2

(Rj^CRjCOO) xM

70 CN

removing excess ammonia source, removing methanol if used as a solvent, and 75 reacting said aminonitrile metal carboxylate with from about 1.0 to about 2.5 equivalents Mi(OCI)x per mole of keto acid with the proviso that no alcohol or surface active agent is utilized with Mi(OCl)x wherein Mi is a metal comprising sodium, potassium, or calcium and x is the valence of Mi to form an azodinitrile metal carboxylate comprising

20 Rl Rl

("00CRoC-N=N-CR,C00") ,2Mx+ I I 25 CN CN

reducing excess M^OCI)* with a reducing agent, and further neutralizing the azodinitrile metal carboxylate to form 30 R- Rl I I HOOCR,C-N=N-CR,COOH I I 35 CN CN

1 about 6 carbon atoms, and R2 2. The process of Claim 1 , wherein Ri is an alkyl group containing from to is an alkylene group containing from 1 to about 6 carbon atoms, or a cycloalkylene group containing from 40 about 3 to about 6 carbon atoms, wherein the molar ratio of said keto acid to said ammonia source is 1:1- 1.5, wherein the molar ratio of said metal cyanide to said keto acid is 1-1.5:1, and wherein the molar ratio of said metal hypochlorite to said keto acid is 1 :1 .2 to 2.0. 3. The process of any preceding claim, wherein the reducing agent is sodium bisulfite or sodium sulfite in with an amount up to about 100 percent excess, wherein the azodinitrile metal carboxylate is neutralized a 45 mineral acid comprising nitric acid, sulfuric acid, or hydrochloric acid, wherein said solvent is water or methanol, and wherein said ammonia source is ammonia or ammonia hydroxide. 4. A process for the preparation of symmetrical azo compounds, comprising, reacting a keto acid

R1CR2COOH

55 wherein Ri is an alkyl group containing from 1 to about 12 carbon atoms, and R2 is a direct bond, or an alkylene group containing from 1 to about 12 carbon atoms with from 1 to about 2 equivalents of M(CN)X calcium per mole of keto acid, wherein M is a metal comprising lithium,' sodium, potassium, magnesium, or

23 EP 0 436 183 A1

and x is the valence of M to form a cyanohydrin metal carboxylate of the formula

OH I (I^CRjCOO)^

10 and reacting said cyanohydrin metal carboxylate with an ammonia source in a molar ratio of keto acid:ammonia source of from about 1:1-4 in the presence of a solvent to form an aminonitrile metal carboxylate of the formula 75

NHL I (Rl

removing excess ammonia source, 25 reacting said aminonitrile metal carboxylate with from about 1.0 to about 2.5 equivalents Mi(OCI)x per mole of keto acid with the proviso that no alcohol or surface active agent is utilized wherein Mi is a metal comprising sodium, potassium, or calcium and x is the valence of Mi to form an azodinitrile metal carboxylate comprising

30 R. R, • I - x ( OOCRr>C-N=N-CRr)COO ) 2MX+ I I CN CN

reducing excess Mi (OCI)X with a reducing agent, and further neutralizing the azodinitrile metal carboxylate to form

40 R, Rl I I HOOCR,C-N=N-CR-COOH 2| I 45 CN CN

5. The process of Claim 4, wherein Ri is a methyl group and R2 is an ethyl group, wherein M equals sodium, and wherein the ammonia source is ammonium hydroxide, and the solvent is water. 50 6. The process of any preceding claim, wherein the reducing agent is in an amount from about 0 to about 10 percent excess, wherein the neutralization agent is hydrochloric acid, wherein the temperature of the reaction for the intermediates is from about 30 °C to about 40 °C, and the reaction temperature for the ° ° coupling reactions is from about 0 C to 1 0 C. 7. The process of any preceding claim, wherein R1 is an alkyl group containing from 1 to about 6 carbon 55 atoms, and R2 is an alkylene group containing from 1 to about 6 carbon atoms, or a cycloalkylene group containing from about 3 to about 6 carbon atoms, wherein the molar ratio of said keto acid to said ammonia source is 1:1-1.5, wherein the molar ratio of said metal cyanide to said keto acid is 1-1.5:1, wherein the molar ratio of said metal hypochlorite to said keto acid is 1 :1 .2 to 2.0; and

24 EP 0 436 183 A1

wherein the reducing agent is sodium bisulfite or sodium sulfite in an amount up to about 100 percent excess. 8. The process of any preceding claim, wherein the azodinitrile metal carboxylate is neutralized with a mineral acid comprising nitric acid, sulfuric acid, or hydrochloric acid, wherein said solvent is water or 5 methanol, and wherein said ammonia source is ammonia or ammonia hydroxide; and wherein Ri is a methyl group and R2 is an ethyl group. is 9. The process of any preceding claim, wherein M equals sodium, and wherein the ammonia source ammonium hydroxide, and the solvent is water, wherein the reducing agent is in an amount from about 0 to about 1 0 percent excess; 10 wherein the neutralization agent is hydrochloric acid; and wherein the temperature of the reaction for the intermediates \s from about 30 °C to about 40 C, and the reaction temperature for the coupling reactions is from about 0 C to 10 C. 10. A process for the preparation of mixed, symmetrical azonitrile initiators, comprising; forming 75

Rl* Rl I I HOOCR2C-N=N-CR2COOH I and 20 cn cn

R4 R4 R3C-N=N-CR3 II CN CN

30 by reacting a keto acid of the formula

o RlCR2COOH

wherein R1 is an alkyl group containing from 1 to about 12 carbon atoms and R2 is a direct bond, or an about alkylene group containing from 1 to about 12 carbon atoms or a cycloalkylene group containing from 40 3 to about 12 carbon atoms, with from 1 to about 2 equivalents of M(CN)X per mole of keto acid wherein M is a metal comprising lithium, sodium, potassium, magnesium, or calcium and x is the valence of M and an ammonia source in a molar ratio of keto acid: ammonia source of from about 1:1-4 in the presence of a solvent to form an aminonitrile metal carboxylate of the formula

45 NH2 (R1CR2COO) xM CN

50 removing excess ammonia source, removing methanol if used as a solvent, reacting said aminonitrile metal carboxylate with Mi (OCI)X in the presence of a surfactant wherein Mi is a metal comprising sodium, potassium, or calcium and x is the valence of M to form an azonitrile metal carboxylate comprising 55

25 EP 0 436 183 A1

R. R. I1 I1 (-OOCR,C-N=N-CR2COO-)\M\^ IX IT Wi\A 2MX+ III CN CN

and also 10 reacting an aminonitrile of the formula

RC-NH2 CN

in the presence of a surfactant and Mi (OCI)X to form a symmetrical azonitrile initiator

II R,C-N=N-CR-3 3, , CN CN

25 wherein R3 and R* are alkyl groups independently containing from 1 to about 12 carbon atoms or one of R3 and R4. is an alkoxy group of from 1 to about 4 carbon atoms wherein the molar ratio of aminonitrile metal carboxylate:aminonitrile is from about 0.5-10:1, wherein the surfactant is from about 0.05 percent active to about 0.20 percent active by weight based on the total weight of aminonitrile metal carboxylate and 30 aminonitrile, and wherein the equivalent weight ratio of the sum of the aminonitrile metal carboxylate and aminonitrile: Mi(OCI)x is from about 1:1.0-2.75, and reducing excess Mi(0CI)x with a reducing agent and further neutralizing the metal azonitrile carboxylate to form

35 R. Rj

HO0CR,C-N=N-CR,C00H2 I 2, , CN CN 40

1 1 . The process of Claim 1 , wherein R1 is an alkyl group containing from 1 to about 6 carbon atoms, and R2 is an alkaline group containing from 1 to about 6 carbon atoms, or a cycloalkaline group containing from about 3 to about 6 carbon atoms, wherein the molar ratio of said keto acid to said ammonia source is 1:1- 45 1.5, wherein the molar ratio of said metal cyanide to said keto acid is 1-1.5:1, and wherein said surfactant is cationic and said surfactant is from about 0.08 percent to about 0.20 percent active. 12. The process of any preceding claim, wherein R3 and R4 are methyl groups, or R3 is a methyl group and R4 is an ethyl group and said aminonitrile metal carboxylate: aminonitrile ratio is from about 0.5-5:1, and said equivalent weight ratio of the sum of aminonitrile metal carboxylate and aminonitrile: Mi (OCI)X is 50 from about 1:1.1-2.0, wherein said ammonia source is gaseous ammonia or concentrated ammonium hydroxide, and wherein said solvent is water or methanol, wherein said reducing agent is sodium bisulfite or sodium sulfite, wherein M is sodium, and wherein the azonitrile metal carboxylate is neutralized with a mineral acid comprising nitric acid, sulfuric acid, or hydrochloric acid. 13. A process for the preparation of mixed, symmetrical azo compounds, comprising; 55 reacting a keto acid

26 EP 0 436 183 A1

0 II R1CR2COOH

5 wherein Ri is an alkyl group containing from 1 to about 12 carbon atoms and R2 is a direct bond, or an alkylene group containing from 1 to about 12 carbon atoms with from 1 to about 2 equivalents of M(CN)X calcium per mole of keto acid, wherein M is a metal comprising lithium, sodium, potassium, magnesium, or and x is the valence of M to form a cyanohydrin metal carboxylate of the formula 10 OH

(RjCRjCOO) XM and CN 15

reacting said cyanohydrin metal carboxylate with an ammonia source in a molar ratio of keto acid:ammonia source of from about 1:1-4 in the presence of water as a solvent to form an aminonitrile metal carboxylate of the formula 20

NH, / 2 (R1CR2COO) xM t 25 CN

removing excess ammonia source by reacting said aminonitrile metal carboxylate with Mi(OCI)x in the calcium and is the presence of a surfactant wherein Mi is a metal comprising sodium, potassium, or x 30 valence of Mi to form an azonitrile metal carboxylate comprising

R1 Ri I | ("OOCR2C-N=N-CR2COO")x2Mx'r III 35 v 2 T | 4 CN CN

and also 40 reacting an aminonitrile of the formula

Rv* R-C-NH- 3/ 2 45 CN

azonitrile in the presence of a surfactant and Mi(OCI)x and x is the valence of Mi to form a symmetrical initiator 50

R,C-N=N-CR, II 3, , 3 CN CN 55

wherein R3 and R+ are alkyl groups independently containing from 1 to about 12 carbon atoms or one of R3 metal and R+ is an alkoxy group of from 1 to about 4 carbon atoms wherein the molar ratio of aminonitrile

27 EP 0 436 183 A1

carboxylate:aminonitrile is from about 0.5-10:1, wherein the surfactant is from about 0.05 percent active to about 0.20 percent active by weight based on the total weight of aminonitrile metal carboxylate and aminonitrile, and wherein the equivalent weight ratio of the sum of the aminonitrile metal carboxylate and aminonitrile: Mi(OCI)x is from about 1:1.0-2.75, and reducing excess Mi (OCI)X with a reducing agent and further neutralizing the azonitrile metal carboxylate to form

Rl Rl HOOCR2C-N=N-CR2COOH I CN CN

75 14. The process of Claim 13, wherein Ri is an alky] group containing from 1 to about 3 carbon atoms, and R2 is an alkaline group containing from 1 to about 3 carbon atoms or a cycloalkaline group containing from about 3 to about 6 carbon atoms, wherein the molar ratio of said keto acid to said ammonia source is 1:1- 1.2, and wherein the molar ratio of said metal cyanide to said keto acid is 1-1.1:1, and wherein said 20 surfactant is cationic and said surfactant is from about 0.12 to about 0.2 percent active. 15. The process of any preceding claim, wherein R3 and R+ are methyl groups, or R3 is a methyl group and R4. is an ethyl group and said aminonitrile metal carboxylate: aminonitrile ratio is from about 0.9-1 .1 :1 and said equivalent weight ratio of the sum of the aminonitile metal carboxylate and aminonitrile: Mi (OCL)X is from about 1 :1 .2-1 .5, and wherein said ammonia source is gaseous ammonia or concentrated ammonium 25 hydroxide, wherein said reducing agent is sodium bisulfite or sodium sulfite, wherein M is sodium, and wherein the azonitrile metal carboxylate is neutralized with a mineral acid of HCL. 16. A process for the preparation of mixed azonitrile initiators, comprising; forming

R. R, 1 1 1 30 1I ' HOOCR-C — N=N— CR,COOH I , 2, 1 2 CN CN

35 RA Ra I4 I4 R,C— N=N— CR, II and 3, , 3 CN CN 40 R. R, I4 I1 N=N— • III R,C— CR,COOH2 3I I CN CN

by reacting a keto acid of the formula

50 R1CR2COOH

with M(CN)X and a catalytic amount of hydrochloric acid to form a cyanohydrin metal carboxylate of the 55 formula

28 EP 0 436 183 A1

(I^CRjCOO)^ CN 5

adding to the cyanohydrin metal carboxylate a cyanohydrin of the formula

OH R3CR4 and, CN

75 reacting the mixture with a hydrazine source to obtain a mixture of hydrazo intermediates of the formulae

R, H H R. II I I (-OOCR2C-N-N — CR2COO")JC2MX+ IV 20 CN CN

*•???• V and R,C-N-N— CR,3 25 "33, , , CN CN

R. H H R,

(R3C — N-N-CR2COO }XMX+ VI CN CN

35 and reacting said mixture of hydrazo intermediates with chlorine gas in the presence of acetone solvent to oxidize the mixture of hydrazo intermediates and form the mixed azonitrile initiators wherein Ri is an alkyl group containing from about 1 to about 12 carbon atoms, R2 is a direct bond or an alkylene group containing from 1 to about 12 carbon atoms, or a cycloalkylene or alkyl cycloalkylene group containing from about 3 to about 12 carbon atoms, R3 and R*, independently, are alkyl groups containing from 1 to about 40 12 carbon atoms, or one of R3 and R+ is an alkoxy group containing from 1 to about 4 carbon atoms, and M is a metal comprising lithium, sodium, potassium, magnesium, or calcium. 17. The process of Claim 1, wherein the equivalents of metal cyanide:moles of keto acid is from about 1-2:1, wherein the moles of hydrazine source:moles of keto acid is from about 0.4-0.75:1 . about 0.1- 18. The process of any preceding claim, wherein the molar ratio of cyanohydrin:keto acid is from is 45 10.0:1, and wherein the molar ratio of cyanohydrin plus keto acid:acetone in the hydrazo intermediate from about 1 :5-30. acid is 19. The process of any preceding claim, wherein the equivalents of metal cyanide:moles of keto from about 1-1.1:1, wherein the moles of hydrazine source:moles of keto acid is from about 0.45-0.55:1, wherein the hydrazine source is hydrazine hydrate and M is sodium, and wherein the molar ratio of so cyanohydrin:keto acid is from about 0.8-1 .5:1 . in 20. The process of any preceding claim, wherein the molar ratio of cyanohydrin plus keto acid:acetone the hydrazo intermediate is from about 1:8-10, wherein Ri contains from 1 to about 6 carbon atoms, and R2 acid. is an alkylene group containing from 1 to about 6 carbon atoms, and wherein the keto acid is levulinic 21 . A process for the preparation of mixed azonitrile initiators, comprising; forming 55

29 EP 0 436 183 A1

R1 R1 I1 I1 HOOCR2C - N ==• N- CR2C00H I , CN CN

and 10 R3C-N=N— CR3 II CN CN

R4 Rl R,C— N=N— CR.COOH III 3, , 2 CN CN

20 by reacting a keto acid of the formula

25 RjCRjCOOH

with M(CN)X and a ketone of the formula

30 O II R3CR4

35 in the presence of hydrochloric acid to obtain a mixture of cyanohydrins of the formulae

OH I (R1CR2COO)XM and 40 I CN

OH 45 R,CRA and, Jl * CN

reacting the cyanohydrin mixture with a hydrazine source to obtain a mixture of hydrazo intermediates of so the formulae

30 EP 0 436 183 A1

R H H R,

(-OOCR2C- N- N- CR2COO~}X2MX+ IV, CN CN

V and R-C— N-N- CR-3 3I I CN CN

?5 R. H H R,

(R C-N-N — C R, COO >MX+ VI 3, ,2 x CN CN

20 and, reacting said mixture of hydrazo intermediates with chlorine gas in the presence of acetone solvent to oxidize the mixture of hydrazo intermediates to form the mixed azonitrile initiators wherein Ri is an alkyl group containing from about 1 to about 12 carbon atoms, R2 is a direct bond, or an alkylene group 25 containing from 1 to about 12 carbon atoms, or a cycloalkylene or alkyl cycloalkylene group containing from about 3 to about 12 carbon atoms, R3 and R+, independently, are alkyl groups containing from 1 to about 12 carbon atoms, or one of R3 and R4. is an alkoxy group containing from 1 to about 4 carbon atoms, and M is a metal comprising lithium, sodium, potassium, magnesium, or calcium. 21. The process of Claim 20, wherein the equivalents of metal cyanide:moles of keto acid is from about 1- 30 1.1:1, wherein the moles of hydrazine source:moles of keto acid is from about 0.45-0.55:1, wherein the molar ratio of ketone:keto acid is from about 0.8-1 .5:1 , and wherein the molar ratio of cyanohydrins:acetone in the hydrazo intermediate is from about 1:8-10. 22. The process of any preceding claim, wherein the hydrazine source is hydrazine hydrate, M is sodium and the keto acid is levulinic acid. 35 23. A process for the preparation of mixed azonitrile initiators comprising; forming

R1 Ri — I, 4Q H00CR2C N=N-CR2COOH CN CN

45 I ' and, R3C — n=t N— CR3 II CN CN

?4 Rl R-C — N=N— CR-COOH III 3, , 2 CN CN

by reacting a keto acid of the formula

31 EP 0 436 183 A1

Rj^COOH 5 with M(CN)X and a hydrazine source in the presence of a ketone of the formula

O II 10 R CR4

to obtain a mixture of hydrazo intermediates of the formulae

75 R. H H R, (-OOCR-C-N— N — CR,COO ' ,2MX+ IV, CN CN 20

H< H ? R4 R,C— N — N — CR, V and 1 I 25 CN CN

RA H H R. 30 (R3C— N N— CR2COO">xMx+ VI CN CN

and reacting said mixture of hydrazo intermediates with chlorine gas in the presence of acetone solvent to 35 oxidize the mixture of hydrazo intermediates to form the mixed azonitrile initiators wherein Ri is an alkyl group containing from about 1 to about 12 carbon atoms, R2 is a direct bond or an alkylene group containing from 1 to about 12 carbon atoms, or a cycloalkylene or alkyl cycloalkylene group containing from about 3 to about 12 carbon atoms, R3 and R4, independently, are alkyl groups containing from 1 to about 12 carbon atoms, or one of R3 and R4 is an alkoxy group containing from 1 to about 4 carbon atoms and M 40 is a metal comprising lithium, sodium, potassium, magnesium, or calcium. 24. The process of Claim 23, wherein the equivalents of metal cyanide:moles of keto acid is from about 1- 1.1:1, and wherein the moles of hydrazine source:moles of keto acid is from about 0.45-0.55:1. 25. The process of any preceding claim, wherein the hydrazine source is hydrazine hydrate and M is sodium, wherein the molar ratio of ketone:keto acid is from about 0.8-1.5:1, wherein the molar ratio of 45 cyanohydrins:acetone in the hydrazo intermediate is from about 1:8-10, and the keto acid is levulinic acid.

32 Application Number J European Patent EUROPEAN SEARCH REPORT Office

EP 90124725.4 DOCUMENTS CONSIDERED TO BE RELEVANT where Relevant CLASSIFICATION OF THE Citation of document with indication, appropriate, APPLICATION (Int. Cl-5) ;ategory of relevant passages to claim US - A - 4 272 435 1,4, C 07 C 245/04 (TERUO MATSUDA et al.) 10,13 * Claim 1 *

D,A US - A - 4 028 345 1,4, (EARL PHILLIP MOORE, JR.) 10,13 * Claim 1 *

D,A US - A - 3 783 148 1,4, (JULIUS J. FUCHS) 10,13 * Claim 1 *

D,A US - A - 4 684 718 1,16, (HIDETOMO ASHITAKA et al.) 22,24 * Abstract *

D,A US - A - 4 684 717 1,16, (HIDETOMO ASHITAKA et al.) 22,24 * Abstract *

578 249 1,16, TECHNICAL FIELDS FR - Al - 2 SEARCHED (Int. CI.5) (SOCIETE FRANCAIS D'ORGANO 22,24 SYNTHESE) * Claim 1 * C 07 C 245/00 C 08 F 4/00 US - A - 2 520 338 1,16, (JAMES A. ROBERTSON) 22,24 * Claims 1,3; column 1 , lines 48-55 *

The present search report has been drawn up for all claims Place of searvh Date of completion of the search VIENNA 03-04-1991 REIF

OK CITED DOCUMENTS T : theory or principle underlying the invention CATKGOR\ E : earlier patent document, but published on, or X : particularly rele\ant if taken alone after the filing date V : particularly reliant if combined with another D : document cited in the application document of the- same category L : document cited for other reasons A : technological backsjround corresponding O : non-written disclosure & : member of the same patent family, P : intermediate document document