Acid Monohydrate

Reactions. Mahc acid undergoes many of the characteristic reactions of dibasic acids, monohydric alcohols, and a-hydroxycarboxyUc acids. When heated to 170—180°C, it decomposes to fumaric acid and maleic anhydride which sublimes on further heating (see Maleic anhydride, maleic acid, AND FUMARIC acid). MaUc acid forms two types of condensation products linear malomalic acids and the cycHc dilactone or maUde it does not form an anhydride. 

Argatroban [74863-84-6] ((2R,4R)-4-methyl-l-[A/ -)(3 methyl l,2,3,4-tetrahydto-8-quiaoIiaesulfonyl)-L-atgiayl]-2-piperidiaecatboxyhc acid monohydrate) is a potent inhibitor of thrombin formation and activity (49). This agent has been studied in vitro and ia a few animal models. Its toxicity and activity ia humans ate unknown. 

Citric acid monohydrate [5949-29-1] has a molecular weight of 210.14 and crystallizes from cold aqueous solutions. When gendy heated, the crystals lose thek water of hydration at 70—75°C and melt in the range of 135—152°C. Rapid heating causes dehydration at 100°C to form crystals that melt sharply at 153°C. Citric acid monohydrate is available in limited commercial quantities since most appHcations now call for the anhydrous form. 

Isobutyraldehyde, allyl alcohol, p-cymene, and p-toluenesulfonic acid monohydrate were purchased from Aldrich Chemical Company, Inc., and used as received. 

A. 2-f2-Bmmoetkyl)-l,3-diozane (1), A 2-L, three-necked flask Is equipped with a mechanical stirrer, thermometer, and gas Inlet tube. In the flask are placed 750 ml of dichloromethane, 112 g (2.00 moll of acrolein (Note 1), and 0.10 g of didnnamalacetone Indicator (Note 2) under nitrogen. The yellow solution is cooled to 0-5°C with an Ice bath. Gaseous hydrogen bromide (Note 3) is bubbled Into the solution with stirring until the Indicator becomes deep red (Note 4). The Ice bath is removed and 1.0 g of p-toluene-sulfonic acid monohydrate and 152.2 g (2.00 mol, 144 mL) of 1,3-propanediol (Note 11 are added. The yellow solution is stirred at room temperature for 8... 

Cinnamaldehyde dimethylacetal is prepared by the method used to prepare the corresponding diethylacetal. A mixture of 66.0 g. (0.5 mole) of Aldrich Chemical Company, Inc.), 100 g. (1.06 mole) of trimethyl orthoformate (Eastman Organic Chemicals), 450 ml. of anhydrous methanol (J. T. Baker Chemical Company), and 0.5 g. ofp-toluenesulfonic acid monohydrate (Fisher Scientific Company) is stirred at room temperature for 24 hours. At the end of this time the alcohol is removed with a rotary evaporator and the residue is distilled to give 81-83 g. (91-93%) of cinnamaldehyde dimethylacetal, b.p. 93—96° (0.2 mm.). 

A good commercial grade of />-toluenesulfonic acid monohydrate, m.p. 104-106°, was used. 

In a 2-1. flask fitted with a total-reflux, variable-take-off distillation head is placed a solution of 53 g. (0.472 mole) of dihydroresorcinol (Note 1), 2.3 g. of -toluenesulfonic acid monohydrate and 250 ml. of absolute ethanol in 900 ml. of benzene. The mixture is heated to boiling and the azeotrope composed of benzene, alcohol, and water is removed at the rate of 100 ml. per hour. When the temperature of the distilling vapor reaches 78° (Note 2), the distillation is stopped and the residual solution is washed with four 100-ml. portions of 10% aqueous sodium hydroxide which have been saturated with sodium chloride. The resulting organic solution is washed with successive 50-ml. portions of water until the aqueous washings are neutral and then concentrated under reduced pressure. The residual liquid is distilled under reduced pressure. The yield of 3-ethoxy-2-cyclohexenone (Note 3), b.p. 66-68.5°/0.4 mm. or 115-121°/11 mm., Mq 1.5015, is 46.6-49.9 g. (70-75%). 

The alkaline filtrate and washings are combined and partially neutralized by the addition of 150-175 ml. of concentrated hydrochloric acid. Sufficient sodium sulfide solution is added to precipitate all the lead ion present (Note 6). The suspension is brought to a gentle boil to coagulate the lead sulfide, allowed to cool somewhat, and filtered with suction. The filtrate is placed in a 2-1. beaker set in an ice bath and acidified Caution in the hood) with about 150 ml. of concentrated hydrochloric acid to precipitate crude 2-hydroxyisophthalic acid monohydrate (Note 7). The suspension is cooled to 0-5° and filtered to separate the crude acid, which weighs 35-49 g. after being dried in a vacuum oven at 110°/50-150 mm. for 5 hours (Note 8). 

ChemicalDesignations-i(yntr nu Gallic acid monohydrate 3,4,5-Trihydroxybenzoicacid Chemical Formula 3,4,5-(HO)3CjHiCOOH HiO. 

Dipping solution Dissolve 100 mg of 8-anilinonaphthalene-l-sulfonic acid ammonium salt in a mixture of 40 ml caustic soda solution (c = 0.1 mol/1) and 57 ml of an aqueous solution containing 21 g citric acid monohydrate and 8 g sodium hydroxide per hter. 

In a 250 ml Erlenmeyer flask covered with aluminum foil, 14.3 g (0.0381 mole) of 17a-acetoxy-3j5-hydroxypregn-5-en-20-one is mixed with 50 ml of tetra-hydrofuran, 7 ml ca. 0.076 mole) of dihydropyran, and 0.15 g of p-toluene-sulfonic acid monohydrate. The mixture is warmed to 40 + 5° where upon the steroid dissolves rapidly. The mixture is kept for 45 min and 1 ml of tetra-methylguanidine is added to neutralize the catalyst. Water (100 ml) is added and the organic solvent is removed using a rotary vacuum evaporator. The solid is taken up in ether, the solution is washed with water and saturated salt solution, dried over sodium sulfate, and then treated with Darco and filtered. Removal of the solvent followed by drying at 0.2 mm for 1 hr affords 18.4 g (theory is 17.5 g) of solid having an odor of dihydropyran. The infrared spectrum contains no hydroxyl bands and the crude material is not further purified. This compound has not been described in the literature. 

Bisethylenedioxypregn-5-ene. Method A. A mixture of progesterone (10 g), freshly distilled ethylene glycol (80 ml) and benzene (350 ml) is slowly distilled for 15 min to remove traces of water. p-Toluenesulfonic acid monohydrate (0.3 g) is added and the mixture is heated under reflux with stirring for 5 hr with a water separator. Saturated sodium bicarbonate solution is added to the cooled mixture and the benzene layer is separated. The organic layer is washed twice with water, dried and evaporated in vacuo. The residue is crystallized twice from acetone-methanol to give 4.15 g (32%) of bisketal, mp 178-181°. 

An improved yield of ketal is obtained by heating a solution of 2 g of progesterone in 16 ml of ethylene glycol and 70 ml of toluene containing 65 mg of / -toluenesulfonic acid monohydrate at reflux for 4 hr. The yield of bisethy-lene ketal is 1.34 g (67%), mp 178-182°. 

Testosterone. 3,3-Ethylenedioxyandrost-5-en-17 -ol (1 g) is dissolved in anhydrous acetone (50 ml), p-toluenesulfonic acid monohydrate (50 mg) is added and the mixture is heated under reflux for 14 hr. Concentration of the resulting solution to a small volume (10 ml) and precipitation with water gives a quantitative yield of slightly impure testosterone (0,87 g, 100%), mp 147-151°. Recrystallizatioii from ether furnishes the pure product of mp 152-154° [ ]d 109° (CHCI3). 

Androst-4-ene-3,l7-dione 3-Ethylene Thioketal A solution of androst-4-ene-3,17-dione (1.42 g, 5 mmoles) in acetic acid (20 ml) is treated with ethanedithiol (0.47 g, 5 mmoles) and a solution of 0.45 of p-toluenesulfonic acid monohydrate in acetic acid (5 ml). After 1 hr at room temperature, the pale yellow solution is poured into water and the resulting suspension is extracted with chloroform. The chloroform solution is washed with water, 5 % sodium hydroxide solution and water, dried (Na2S04) and evaporated. Chromatography of the resulting oil (1.93 g) over silica gel yields androst-4-ene-3,17-dione bisethylene thioketal, mp 173-175° [0.16 g, eluted with petroleum ether-benzene (1 2)] and androst-4-ene-3,17-dione 3-ethylene thioketal, mp 173-176° [1.38 g (76%), eluted with benzene-ethyl acetate (19 1)]. 

Methoxypregna-3,5-dien-20-oned A solution of progesterone (0.3 g) dissolved in 5 ml of 2,2-dimethoxypropane-dimethylformamide (1 1) is treated with p-toluenesulfonic acid monohydrate (8 mg) and 0.1 ml of methanol and then heated under reflux for 3.5 hr. The cooled solution is neutralized with 45 mg of sodium bicarbonate, dissolved in 200 ml of ice water, stirred for 0.5 hr and filtered. The enol ether thus obtained (0.29 g, 92%) is purified by crystallization from acetone-methanol containing a trace of pyridine mp 135-160° [a]o —61° (CHCI3). 

AT-Di- N-pyrwlidinyI)-androsta-3,5, 6-tnen-ll-one. A mixture of and-rost-4-ene-3,ll,17-trione (1.5 g, 0.005 mole), benzene (20 ml), pyrrolidine (1.67 ml) and p-toluenesulfonic acid monohydrate (10 mg), is heated under reflux with stirring, a graduated trap being used to collect the water produced from the reaction. Two molar eq of water are collected during 3.5 hr. 

The hydration of 5-amino-3-cyano-l-(2,6-dichloro-4-trifluoromethylphenyl)-4-ethynylpyrazole was performed with p-toluenesulfonic acid monohydrate in acetonitrile (2 h, room temperature) to give the corresponding 4-acetyl derivative. An alkyl substituent at the triple bond decreases the rate of hydration the conversion of 5-amino-3-cyano-l-(2,6-dichloro-4-trifiuoromethylphenyl)-4-(prop-l-yn-l-yl) pyrazole to the 4-propanoylpyrazole was completed after 18 h (98INP9804530 99EUP933363). 

A mixture of cyclohexanone (11.8 g, 0.12 mole), ethylene glycol (8.2 g, 0.13 mole), /j-toluenesulfonic acid monohydrate (0.05 g), and 50 ml of benzene is placed in a 250-ml round-bottom flask fitted with a water separator and a condenser (drying tube). The flask is refluxed (mantle) until the theoretical amount of water (approx. 2.2 ml) has collected in the separator trap. The cooled reaction mixture is washed with 20 ml of 10 % sodium hydroxide solution followed by five 10-ml washes with water, dried over anhydrous potassium carbonate, and filtered. The benzene is removed (rotary evaporator) and the residue is distilled, affording l,4-dioxaspiro[4.5]decane, bp 65-67713 mm, 1.4565-1.4575, in about 80% yield. 

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