WO2022223696A1 - Process for synthesis of n-alkyl-n-phenyl hydrazine - Google Patents

Abstract

The invention provides a process for synthesizing N-alkyl-N-phenyl hydrazine which is devoid of any organic solvents and can be carried out at lower temperatures. The process is environmental-friendly and gives better yield and high purity of the N-alkyl-N-phenyl hydrazine.

Description

Process for synthesis of N-Alkyl-N-phenyl hydrazine

Field of the invention

The invention relates to a process for synthesizing N-alkyl-N-phenyl hydrazine. More specifically, it relates to a green method for the synthesis of N-alkyl-N-phenyl hydrazine which is devoid of any organic solvents.

Background of the invention

Phenylhydrazines are used to making dyes, drugs, and are also used as developer. They are also important reagents for identification of carbonyl group and can be used for identifying aldehydes, ketones and carbohydrates. The hydrazone generated through phenylhydrazine or 2, 4-dinitrophenylhydrazine can be used to identify aldehydes and ketones. It can trigger Fischer indole synthesis upon reaction with aldehydes and ketones (first found by the Emil Flermann Fischer in 1883, the reaction is using phenylhydrazine and aldehyde, ketone for heating and rearrangement under acid-catalysis for the elimination of one molecule of ammonia to give 2-or 3-substituted indole) to give indole ring-class compound. Phenylhydrazines are the first synthetic hydrazine derivatives which can often be used as intermediates of organic dyes, pharmaceuticals and pesticides. They can also be used as organic intermediates for synthesis of pyrazolines, triazoles, and indoles; and as dye intermediates like disazo dye intermediates such as 1-phenyl-3-methyl-5-pyrazolone and so on. They can also be used as pharmaceutical intermediates for preparation of antipyretic, analgesic, anti-inflammatory drugs such as antipyrine and aminopyrine, etc; They can also be used as photography drugs (photosensitive dye); phenylhydrazine is also the raw material for the production of pesticides "imputed phosphorus".

US-6852890 describes synthesis of halogen derivatives of phenyl hydrazine, however, the process involves diazotizing an aniline derivative and then reacting the diazonium salt with sulfurous acid or sulphite salts or hydrogensulfite salts. A few processes known in literature describe the use of organic solvents and are hence, difficult for scale-up. Also, the yield obtained is very less and so the methods are not desirable.

Summary of the invention

Accordingly, the inventors have developed a process for synthesis of alkyl phenyl hydrazines which is environmentally safe and does not involve hazardous solvents.

In one aspect the present invention relates to a process for synthesizing N-alkyl- N-phenyl hydrazine that is eco-friendly.

In another aspect the present invention relates to a process for synthesizing N-alkyl-N-phenyl hydrazine which improves the yield significantly.

Brief description of drawings

Fig. 1 shows the LCMS chromatogram depicting N-Nitroso-N-ethyl aniline. Fig. 2 shows the LCMS chromatogram depicting N-ethyl-N-phenyl hydrazine.

Detailed description of the invention

In this application, including in all embodiments of all aspects of the present invention, the following definitions apply unless specifically stated otherwise. Unless otherwise stated, all percentages are by weight (w/w) of the respective component or the total composition, respectively. “wt.-%” means percentage by weight; “vol.-%” means percentage by volume; “mol-%” means percentage by mole. Unless otherwise stated, all ratios are weight ratios (weight per weight). Preferably, references to ‘parts’ e.g. a mixture of 1 part X and 3 parts Y, is a ratio by weight. +/- indicates the standard deviation. All ranges are inclusive and combinable. Unless otherwise stated, all measurements are understood to be made at 23 °C and at ambient conditions, where “ambient conditions” means at approximately 1 atmosphere (atm) of pressure and at about 50% relative humidity. “Relative humidity” refers to the ratio (stated as a percent) of the moisture content of air compared to the saturated moisture level at the same temperature and pressure. Relative humidity can be measured with a hygrometer, in particular with a probe hygrometer from VWR^® International. Herein “min” means “minute” or “minutes”. Herein “mol” means mole. Herein “g” following a number means “gram” or “grams”. “Ex.” means “example”. All amounts as they pertain to listed ingredients are based on the active level (‘solids’) and do not include carriers or by-products that may be included in commercially available materials.

As used herein the term "comprising" is meant not to be limiting to any subsequently stated elements but rather to encompass non-specified elements of major or minor functional importance. In other words, the listed steps, elements or options need not be exhaustive. Whenever the words "including" or "having" are used, these terms are meant to be equivalent to "comprising" as defined above. Where the compositions of the subject invention are described as "including" or "comprising" specific components or materials, narrower embodiments where the compositions can "consist essentially of" or "consist of" the recited components or materials are also contemplated.

“Derivatives” includes but is not limited to, amide, ether, ester, amino, carboxyl, acetyl, acid, salt and/or alcohol derivatives of a given compound. In at least one embodiment, “derivatives thereof” means the amide, ether, ester, amino, carboxyl, acetyl, acid, salt and alcohol derivatives.

In accordance with the present invention, there is provided a process of synthesizing N-alkyl-N-phenyl hydrazine comprising, i. contacting N-nitroso-n-alkyl aniline with water, ii. adding at least one base, at least one surfactant and at least one organosulfur compound to the reaction mass, iii. optionally heating the reaction mass, iv. optionally filtration of the organic layer to obtain the final product. In general, the at least one base, the at least one surfactant and the at least one organosulfur compound are added to the reaction mass in step ii. at a low temperature of below 20°C.

The organic layer obtained after step ii. or after (optional) step iii may be filtered to obtain the final product. The filtration step iv. may be omitted in some cases.

N-nitroso-N-alkyl aniline can be prepared by a process comprising the steps of

(i) contacting water, at least one acid and N-alkyl aniline in a jacketed reactor at low temperatures,

(ii) adding sodium nitrite to this reaction mass,

(iii) allowing layer separation and filtering the organic layer to obtain the nitroso compound N-nitroso-N-alkyl aniline.

Preferably, the process for the synthesis of N-alkyl-N-phenyl hydrazine comprises the following steps:

1. preparing N-nitroso-N-alkyl aniline comprising the steps of

(i) contacting water, at least one acid and N-alkyl aniline in a jacketed reactor at low temperatures,

(ii) adding sodium nitrite to this reaction mass,

(iii) allowing layer separation and filtering the organic layer to obtain the nitroso compound N-nitroso-N-alkyl aniline;

2. reduction of the N-nitroso-N-alkyl aniline thus obtained by i. contacting with water, ii. adding at least one base, at least one surfactant and at least one organosulphur compound at a low temperature of in general below 20°C, iii. heating the reaction mass and maintaining at 20- 70 °C, preferably for 4 - 7 hours, iv. cooling the reaction mass to allow layer separation, v. filtering the top organic layer to obtain the N-alkyl-N-phenyl hydrazine. Step 1 :

In preferred embodiments, the at least one acid is selected from a group comprising aqueous acids such as hydrochloric acid, nitric acid, sulfonic acids such as sulfuric acid, organic acids such as acetic acid, phosphoric acid, hydrofluoric acid, hydrobromic acid and the like, or mixtures thereof. In most preferred embodiments, the acid is hydrochloric acid.

The molar ratio of N-alkyl aniline to acid may be present in a ratio of 1 : 1.3 to 1 : 10 with the water, most preferably at a ratio of 1 : 1.3 to 1 : 1.7.

The molar ratio of N-alkyl aniline to water is in general from about 1 :30 to 1 :60, most preferably from about 1 :30 to 1 :40.

Preferably the water, the at least one acid and the N-alkyl aniline are mixed at a temperature below 15 °C, most preferably at 0 - 10 °C. The reaction mass is further cooled to a temperature between 0 to 5 °C before adding the sodium nitrite. In preferred embodiments, the molar ratio of N-alkyl aniline to sodium nitrite may range from 1:1.0 to 1:1.2, most preferably from.1 :1.05 to 1:1.1 In preferred embodiments the addition of sodium nitrite is done gradually over a period ranging from 0 - 3 hours, most preferably 1 - 2 hours.

According to one embodiment of the present invention the reaction mass is allowed to stand at a temperature ranging from 0 to 5 °C for 1 - 7 hours to allow layer separation. More preferably, the reaction mass is allowed to stand for at least 4 hours for the layers to separate.

The organic layer is filtered to obtain the N-nitroso-N-alkyl aniline according to a preferred embodiment of the present invention. The purity of the compound thus obtained is at 98 - 99%. In preferred embodiments, the N-nitroso-N-alkyl aniline thus obtained is used in Step 2 for preparing the N-alkyl-N-phenyl hydrazine. In certain embodiments the N-nitroso-N-alkyl aniline used in Step 2 can be obtained from commercial sources. In certain other embodiments, the N-nitroso-N- alkyl aniline used in Step 2 can be prepared by methods known in prior art. US-2880240 is incorporated herein as a reference.

The N-alkyl anilines used in the Step 1 above can be a Ci - C22 alkyl aniline. Suitable examples include, but are not limited to methyl aniline, ethyl aniline, isopropyl aniline, butyl aniline, pentyl aniline, hexyl aniline, heptyl aniline, and the like. In at least one embodiment, the N-alkyl aniline is a N-ethyl aniline.

Step 2:

According to the present invention, the N-nitroso-N-alkyl aniline is contacted with water, at least one base, at least one surfactant and at least one organosulfur compound in steps i. and ii. of the process.

The at least one base used in accord with the present invention in step 2 ii. may be selected from water-soluble inorganic bases and water-soluble organic amine bases. Suitable bases are for example alkali and earth alkali metal hydroxides, alkali and earth alkali metal carbonates, and amines; for example alkali metal hydroxides, alkali metal carbonates, and amines. Preferred alkali metal hydroxides are LiOH, NaOH and KOH. Preferred alkali metal carbonates are U2CO3, Na₂C03 and K2CO3. Preferred amines are of formula N(R²)3 with R² being independently from each other selected from H and alkyl groups with 1 to 6 carbon atoms, e.g., NH3, NMe3, and NEt3, preferably NH3. According to the present invention, the preferred base is an alkali metal hydroxide, more preferably NaOH, KOH or a combination thereof.

According to the present invention the molar ratio of N-nitroso-N-alkyl aniline to the base may be in the range of from 1 :2 to 1:10. It may be preferred that the molar ratio is in the range of from 1 :3 to 1 :8, more preferably of from 1 :4 to 1 :7.

Any of a variety of surfactants can be used in step 2 ii. in accord with the present invention. Suitable examples of surfactants include anionic surfactants, nonionic surfactants, cationic surfactants, zwitterionic surfactants and/or amphoteric surfactants.

Non-limiting examples of anionic surfactants include of (Cio-C₂o)-alkyl and alkylene carboxylates, alkyl ether carboxylates, fatty alcohol sulfates, fatty alcohol ether sulfates, alkylamide sulfates and sulfonates, fatty acid alkylamide polyglycol ether sulfates, alkanesulfonates and hydroxyalkanesulfonates, olefinsulfonates, acyl esters of isethionates, a-sulfo fatty acid esters, alkylbenzenesulfonates, alkylphenol glycol ether sulfonates, sulfosuccinates, sulfosuccinic monoesters and diesters, fatty alcohol ether phosphates, protein/fatty acid condensation products, alkyl monoglyceride sulfates and sulfonates, alkylglyceride ether sulfonates, fatty acid methyltaurides, fatty acid sarcosinates, sulforicinoleates, acylglutamates, and mixtures thereof. The anionic surfactants (and their mixtures) can be used in the form of their water-soluble or water-dispersible salts, examples being the sodium, potassium, magnesium, ammonium, mono, di-, and triethanolammonium, and analogous alkylammonium salts. In at least one embodiment, the anionic surfactant is the salt of an anionic surfactant comprising 12 to 14 carbon atoms. In at least one embodiment, the anionic surfactant is selected from the group consisting of sodium lauryl sulfate, sodium laureth sulfate, sodium tridecyl sulfate, sodium trideceth sulfate, sodium myristyl sulfate, sodium myreth sulfate, and mixtures thereof.

Non-limiting examples of suitable non-ionic surfactants are ethoxylated or ethoxylated/propoxylated fatty alcohols with a fatty chain comprising from 12 to 22 carbon atoms, ethoxylated sterols, such as stearyl- or lauryl alcohol (EO-7), PEG-16 soya sterol or PEG-10 soya sterol, polyoxyethylene polyoxypropylene block polymers (poloxamers), and mixtures thereof. In at least one embodiment, the non-ionic surfactant is selected from the group consisting of ethoxylated fatty alcohols, fatty acids, fatty acid glycerides or alkylphenols, in particular addition products of from 2 to 30 mol of ethylene oxide and/or 1 to 5 mol of propylene oxide onto Cs- to C22-fatty alcohols, onto C12- to C22-fatty acids or onto alkyl phenols having 8 to 15 carbon atoms in the alkyl group, C12- to C22-fatty acid mono- and diesters of addition products of from 1 to 30 mol of ethylene oxide onto glycerol, addition products of from 5 to 60 mol of ethylene oxide onto castor oil or onto hydrogenated castor oil, fatty acid sugar esters, in particular esters of sucrose and one or two Cs- to C22-fatty acids, INCI: Sucrose Cocoate, Sucrose Dilaurate, Sucrose Distearate, Sucrose Laurate, Sucrose Myristate, Sucrose Oleate, Sucrose Palmitate, Sucrose Ricinoleate, Sucrose Stearate, esters of sorbitan and one, two or three Cs- to C22-fatty acids and a degree of ethoxylation of from 4 to 20, polyglyceryl fatty acid esters, in particular of one, two or more Cs- to C22-fatty acids and polyglycerol having preferably 2 to 20 glyceryl units, alkyl glucosides, alkyl oligoglucosides and alkyl polyglucosides having Cs to C22-alkyl groups, e.g. decylglucoside or laurylglucoside, and mixtures thereof. In at least one embodiment, the non-ionic surfactant is selected from the group consisting of fatty alcohol ethoxylates (alkylpolyethylene glycols), alkylphenol polyethylene glycols, alkylmercaptan polyethylene glycols, fatty amine ethoxylates (alkylaminopolyethylene glycols), fatty acid ethoxylates (acylpolyethylene glycols), polypropylene glycol ethoxylates (Pluronics^®), fatty acid alkylol amides, (fatty acid amide polyethylene glycols), N-alkyl-, N-alkoxypolyhydroxy-fatty acid amide, sucrose esters, sorbitol esters, polyglycol ethers, and mixtures thereof. In certain most preferred embodiments, the nonionic surfactant is selected from polyglycol ethers, fatty alcohol ethoxylates, and mixtures thereof.

Non-limiting examples of suitable cationic surfactants are behenyl trimethyl ammonium chloride, methyl sulfate or ethyl sulfate, and stearyl trimethyl ammonium chloride, methyl sulfate or ethyl sulfate. In at least one preferred embodiment, the cationic surfactant is a di-long alkyl quaternized ammonium salt selected from the group consisting of: dialkyl (14 - 18) dimethyl ammonium chloride, ditallow alkyl dimethyl ammonium chloride, dihydrogenated tallow alkyl dimethyl ammonium chloride, distearyl dimethyl ammonium chloride, dicetyl dimethyl ammonium chloride, and mixtures thereof. In at least one preferred embodiment, the cationic surfactant is a tertiary amido amine having an alkyl group of from 12 to 22 carbons. The tertiary amido amine may be selected from the group consisting of stearamidopropyldimethyl-, stearamidopropyldiethyl-, stearamidoethyldiethyl-, stearamidoethyldimethyl-, palmitamidopropyldimethyl-, palmitamidopropyldiethyl-, palmitamidoethyldiethyl-, palmitamidoethyldimethyl-, behenamidopropyldimethyl behenamidopropyldiethyl-, behenamidoethyldiethyl-, behenamidoethyldimethyl-, arachidamidopropy Idimethy 1-, arachidamidopropyldiethyl-, arachidamidoethyldiethyl-, and arachidamidoethyldimethyl-amine, diethylaminoethylstearamide, and mixtures thereof. A tertiary amido amine may be used in combination with an acid. The acid is typically used as a salt-forming anion. In at least one preferred embodiment, the acid is selected from the group consisting of lactic acid, malic acid, hydrochloric acid, 1-glumatic acid, acetic acid, citric acid, and mixtures thereof. In at least one preferred embodiment, the cationic surfactant is selected from the group consisting of cetyltrimonium chloride (CTAC), stearyltrimonium chloride (STAC), behentrimonium methosulfate, stearoylamidopropyldimethyl amine (SAPDMA), distearyldimethylammonium chloride, and mixtures thereof.

Non-limiting examples of amphoteric surfactants include those selected from the group consisting of N-(Ci2-Ci8)-alkyl- -aminopropionates and N-(Ci2-Ci8)-alkyl- - iminodipropionates as alkali metal salts or mono-, di-, or trialkylammonium salts; N-acylaminoalkyl-N,N-dimethylacetobetaine, preferably N-(C8-Ci8)- acylaminopropyl-N,N-dimethylacetobetaine, (Ci2-Ci8)-alkyl-dimethyl- sulfopropylbetaine, amphosurfactants based on imidazoline (trade name: Miranol, Steinapon), preferably the sodium salt of 1-( -carboxymethyloxyethyl)-1-(carboxy- methyl)-2-laurylimidazolinium; amine oxide, e.g., (Ci2-Ci8)-alkyl-dimethylamine oxide, fatty acid amidoalkyldimethylamine oxide, and mixtures thereof. In at least one embodiment, the amphoteric surfactant comprises a betaine surfactant selected from Cs- to Ci₈-alkylbetaines. In at least one preferred embodiment, the betaine surfactant is selected from the group consisting of cocodimethylcarboxymethylbetaine, lauryldimethylcarboxymethylbetaine, lauryldimethylalphacarboxyethylbetaine, cetyldimethylcarboxymethylbetaine, oleyldimethylgammacarboxypropylbetaine and laurylbis(2- hydroxypropyl)alphacarboxyethylbetaine and combinations thereof. In at least one preferred embodiment, the betaine surfactant is selected from Cs- to Ci₈-sulfobetaines. In at least one preferred embodiment, the betaine surfactant is selected from the group consisting of cocodimethylsulfopropylbetaine, stearyldimethylsulfopropylbetaine, lauryldimethylsulfoethylbetaine, laurylbis(2- hydroxyethyl)sulfopropylbetaine, and combinations thereof. In at least one preferred embodiment, the betaine surfactant is selected from carboxyl derivatives of imidazole, the Cs- to Ci₈-alkyldimethylammonium acetates, the Cs- to Ci₈-alkyldimethylcarbonylmethylammonium salts, and the Cs- to Cis-fatty acid alkylamidobetaines, and mixtures thereof. In at least one preferred embodiment, the Cs- to Ci ₈-fatty acid alkylamidobetaine is selected from coconut fatty acid amidopropylbetaine, N -coconut fatty acid amidoethyl-N-[2-(carboxymethoxy)ethyl] glycerol (CTFA name: Cocoamphocarboxyglycinate), and mixtures thereof. A particularly preferred amphoteric or betaine surfactant is cocam idopropyl betaine. A further preferred amphoteric or betaine surfactant is sodium cocoamphoacetate.

According to the present invention the quantity of surfactant added may be from 0.01 to 10 wt.-%, more preferably from 1 to 10 wt.-% and most preferably from 2 - 8 wt.-%.

The organosulfur compounds that may be used in step 2(ii) in accord with the present invention include but are not limited to sulfides such as thioacetals and thioketals, thiols, disulfides, polysulfides, thioesters, sulfoxides, sulfones, thiosulfinates, sulfimides, sulfoximides, sulfonediimines, S-Nitrosothiols, sulfur halides, thioketones, thioaldehydes, thiocarbonyl compounds, thiocarboxylic acids, thioamides, sulfonic, sulfinic, sulfenic acids and their esters, amides and related compounds, sulfonium, oxosulfonium and their related salts, sulfonium, oxosulfonium, thiocarbonyl ylides, sulfanes and persulfanes, and naturally occurring organosulfur compounds. In at least one preferred embodiment, the organosulfur compound is selected from thiourea dioxide, sodium thiosulphate, and sodium dithionate and mixtures thereof.

According to the present invention the molar ratio of N-nitroso-N-alkyl aniline to the surfactant may be in the range of from 1:0.001 to 1:0.05. In preferred embodiments the molar ratio is in the range of from 1 :0.001 to 1 :0.02, more preferably of from 1:0.001 to 1:0.015. Preferably, the temperature at which the base, surfactant and organosulfur are added to the reaction mass in step 2 ii. may be below 20 °C, more preferably between 10 - 20 °C, for example between 15 - 20 °C.

In one embodiment the reaction mass of Step 2 ii. is continued to be kept at a temperature ranging from 10 - 20 °.

In another embodiment the reaction mass of Step 2 ii. is heated to a temperature ranging from 20 - 70 °C, most preferably at 45-55 °C and maintained at the same temperature for 4 - 7 hours. The reaction mass is then cooled to a temperature ranging from 25 - 35 °C in the Step 2 iii., preferably to 30 - 32 °C and maintained at the same temperature for 1 - 2 hours.

The compounds used in Step 2 ii. can be combined in any order. It may be preferred that the base is dissolved in water and the surfactant and then the organosulfur compound is added to the resulting solution. Preferably, the organosulfur compound is gradually added to the solution while stirring over a period of 20 - 40 min.

It is preferred according to the present invention that the process is carried out in the absence of an organic solvent.

The compounds of the present invention find wide use as intermediates in the synthesis of a variety of pigments, including Pigment Violet 23, Direct Blue 108, carbazole dioxazine pigments, and the like. The compounds are also used in pharmaceutical industry for synthesis of drugs such as rimcazole, carprofen,

API intermediates such as 9-Ethyl-3-carbazolecarboxaldehyde.

Examples

The following examples are illustrative of the process of the present invention and not to be construed as limiting the scope thereof. Example 1 - Preparation of N-nitroso-n-ethyl aniline

In a 5-litre glass reactor, RBF equipped with water condenser, N2 purging and thermometer, charged 500 ml Water, 1000 ml HCI (35%) and 800 g N-ethyl aniline. All the reagents were added maintaining the temperature below 15 °C. The reaction mass was cooled to 0 - 5 °C by external cooling. To this reaction mass was added NaNC^ solution (492 g dissolved in 1050 ml water) gradually over 1.5 hrs at 0 - 5 °C. The reaction mass was maintained for 2 hours at 0 - 5 °C. The reaction mass was allowed to stand for 1 hr. After layer separation the reaction mass was filtered to obtain 970 g of organic layer (N-Nitroso-N-ethyl-aniline) which was dark brown in colour, and approximately 3000 g of aqueous layer as a colourless solution. The yield of N-Nitroso-N-ethyl-aniline obtained was 94 - 95% and purity was 98 - 99%.

Example 2 - Preparation of N-ethyl-N-phenyl hydrazine (NENPH)

Reduction of the N-Nitroso-N-ethyl-aniline obtained in Example 1 - Charged in a 5-litre glass reactor, RBF equipped with water condenser and thermometer, 2600 ml water and 200 g of N-Nitroso -N-ethyl aniline (Organic layer from Example 1 ). The temperature was maintained below 15 °C. The reaction mass was light brown in colour. To the reaction mass added Sodium hydroxide-98% (320.0 g dissolved in 1000 ml water) at temperature below 15 °C. Then added 4.0 g of Genapol T-250 P followed by Thiourea dioxide 96% (294.4 g powder) in 20-30 mins. Throughout the addition, temperature was maintained below 20°C. No exotherm was observed. Initially, the reaction mass was brown in color, which changed to white slurry and then finally to clear colorless solution. Reaction mass was heated to 50 °C and further maintained for 4 hours at 50 °C. The reaction mass was cooled to 30 °C and allowed to stand for layer separation for 1 hr. Top organic layer obtained was N-ethyl-N-phenyl hydrazine as a light brown colored solution. The aqueous layer was a hazy solution which was extracted with 100 ml X 2 Dichloromethane. After evaporating the dichloromethane, the N-ethyl-N-phenyl hydrazine was obtained as a brown coloured product weighing 156 g (yield - 83 - 85% and purity - 98 - 99%). The aqueous layer was a clear solution containing degradable waste such as urea and was discarded.

Example 3 - Preparation of N-ethyl-N-phenyl hydrazine (NENPH) The process of Example 2 was followed using the quantities of raw materials given in Table 1 below. Also given is the yield of N-ethyl-N-phenyl hydrazine obtained and the purity of the compound.

Table 1

Example 7 - LCMS method for testing the purity of NENPH Table 2 - Solvent Composition

Column Specification:

ECLIPSE plus C18 150X4.6 mm 3.5m Table 3

Mass Spectrometer Detector:

Ionization Mode MM-ES+APCI

Polarity Positive

Fragmentor Ramp Disabled Percent Cycle Time 50.00% Table 4 - Scan Parameters

Spray Chamber [MS Zones]

Gas Temp 345 C maximum 350 C Vaporizer 245 C maximum 250 C Drying Gas 12.0 l/min maximum 13.0 l/min Neb Pres 58 psig maximum 60 psig VCap (Positive) 4500 V VCao (Neaative) 4000 V VCharge (Positive) 2000 V

VCharge (Negative) 2000 V

Corona (Negative) 4.0 mA

Corona (Negative) 40 mA

Table 5 - Retention time and Peaks

The process of the present invention for preparing the N-ethyl-N-phenyl hydrazine is a green process and environmental-friendly as it does not require any organic solvents which are mentioned in prior art. Thus, it is easy and convenient for manufacturing on a large scale and poses less safety hazards.

Claims

Patent claims

1. A process of synthesizing N-alkyl-N-phenyl hydrazine comprising, i. contacting N-nitroso-n-alkyl aniline with water, ii. adding at least one base, at least one surfactant and at least one organosulfur compound to the reaction mass, iii. optionally heating the reaction mass, iv. optionally filtration of the organic layer to obtain the final product.

2. The process of claim 1 comprising i. contacting N-nitroso-n-alkyl aniline with water, ii. adding at least one base, at least one surfactant and at least one organosulfur compound to the reaction mass at low temperatures below 20°C, iii. optionally heating the reaction mass, iv. optionally filtration of the organic layer to obtain the final product.

3. The process of claim 2, wherein the reaction mass of step ii. is kept at a temperature ranging from 10 to 20 °C.

4. The process of claim 2, wherein the reaction mass of step ii. is heated to a temperature ranging from 20 to 70 °C.

5. The process of any one of claims 1 to 4, wherein the base is selected from sodium hydroxide, potassium hydroxide, calcium hydroxide, lithium hydroxide, sodium carbonate, potassium carbonate, calcium carbonate, lithium carbonate, ammonia and mixtures thereof.

6. The process of any one of claims 1 to 5, wherein the surfactant is selected from a group comprising anionic, nonionic, cationic, amphoteric surfactants and mixtures thereof.

7. The process of any one of claims 1 to 6, wherein the surfactant is selected from polyglycol ethers, fatty alcohol ethoxylates, fatty alcohol sulfates, fatty alcohol ether sulfates, alkylamide sulfates and sulfonates, and mixtures thereof.

8. The process of any one of claims 1 to 7, wherein the organosulfur compound is selected from thiourea dioxide, sodium thiosulphate, and sodium dithionate and mixtures thereof.

9. The process of any one of claims 1 to 8, wherein the temperature in step iii. ranges from 45-55 °C

10. The process of any one of claims 1 to 9, wherein N-nitroso-N-alkyl aniline is prepared by a process comprising the steps of (i) contacting water, at least one acid and N-alkyl aniline in a jacketed reactor at low temperatures,

(ii) adding sodium nitrite to this reaction mass,

(iii) allowing layer separation and filtering the organic layer to obtain the nitroso compound N-nitroso-N-alkyl aniline.