Hydrogen 3-nitrophthalates

Hydrogen 3-nitrophthalates. 3-Nitrophthalic anhydride, a yellow crystaUine powder of m.p. 163-164°, reacts with alcohols to yield esters of 3-nitrophthalic acid ... 

The derivative selected in any particular instance should be one which clearly singles out one compound from among all the possibihties and thus enables an unequivocal choice to be made. The melting points of the derivatives to be compared should differ by at least 5-10°. Whenever possible, a derivative should be selected which has a neutralisation equivalent as well as a melting point (e.g., an aryloxyacetic acid derivative of a phenol. Section IV, 114,4, or a hydrogen 3 -nitrophthalate of an alcohol. Section 111,25,5). 

Hydrogen 3-nitrophthalates (3-Niirophlhalic acid monoalkyl esters)... 

If, when the product is cooled, the hydrogen 3-nitrophthalate does not crystallize, extract it with saturated sodium bicarbonate solution and acidify the extract with 2N hydrochloric acid. Recrystallize from aqueous alcohol. 

Heat 3-nitrophthalic anhydride with ammonium carbonate to get 3-nitrophthalimide (I). Dissolve 4.3 g (I) in 50 ml 90% methanol and add 1.9 g sodium borohydride over 30 minutes while stirring vigorously at room temperature. Stir 2 hours, acidify with 20% HCI, evaporate in vacuum and treat the dry residue with acetone. Evaporate in vacuum to get 3.9 g (88%) 3-OH-4-nitrophthal-imidine (II) (recrystallize from acetone). Dissolve 3.9 g (II) in 40 ml 20% HCI and stir for 10 hours on water bath at 80-90°. Distill off HCI and stir residue with acetone. Filter and evaporate in vacuum to get 3.4 g 3-OH-4-nitrophthalide (III) (recrystallize from CHC 3 and can purify on column). Prepare an ether solution of CH2N2 and add to 1.93 g (III) in a 100 ml flask until a reaction is no longer evident. Add acetic acid to decompose excess diazomethane and evaporate in vacuum to get about 2 g of 2-methoxycarbonyl-6-nitrostyrene oxide (IV) (can purify on column). Dissolve 560 mg (IV) in 50 ml absolute methanol, add 50 mg Pt02 and hydrogenate as described elsewhere here (other reducing methods should work). Filter,... 

The synthesis of ionic triiodinated contrast agents starts from either bisamino nitrophthalic acid or amino isophthalic acid. The nitro group is reduced to the amino moiety by hydrogenation. Iodine is introduced in aqueous solution with iodine monochloride. Due to the decrease in solubiHty the resulting triiodobenzene precipitates from the solution and can be recrystallised. Amino functions are then acylated. 

Phthalic anhydrides readily form hydrogen phthalate esters on reaction with alcohols the derivatives from 3-nitrophthalic anhydride are usually nicely crystalline compounds and are hence suitable for purposes of characterisation. Hydrogen phthalate esters are also useful in appropriate instances for the resolution of racemic alcohols (Section 5.19). 

Thiols react with 3-nitrophthalic anhydride to yield hydrogen 3-nitrothio-phthalates (compare Section 9.6.4, p. 1243). 

More commonly, but incorrectly, named thiophthalic anhydride and sometimes referred to as phthaloyl monosulfide or o-phthalyl sulfide, this compound (104) may be prepared by heating phthalic anhydride with sodium sulfide125 or by heating phthaloyl chloride with potassium hydrogen sulfide,126 hydrogen sulfide,127 or ethanolic sodium disulfide.128 The reaction between phthaloyl chloride and hydrogen sulfide also gives phthalic anhydride and di-o-phthaloyl disulfide.127 Early attempts to prepare 104 have been described by Chakravarti.126 4-Nitrophthalic thioanhydride may be prepared by hydrolysis of 8 (R = N02 X = C1) (Section III, A).22... 

CgHaNOs) 3-Nitrophthalic anhydride F. Loss of hydrogen cyanide from metastable ions indicates that molecule lost is HC N. indicates that molecule lost is H CN. indicates that molecule lost is DCN. 110 g, m 116... 

The synthesis of m-IBX employs 3-nitrophthalic acid. Esterfi-cation of the acid chloride, after treatment with methanol, gives the nitrodiester. Catal)dic hydrogenation affords the corresponding aminodiester, and diazotization followed by iodination with KI provides the dimethyl iodophthalate. Saponification of the diester with NaOH, and acidic work-up give the m-IBX diacid precursor. Oxidation of the diacid with KBrOs in dilute acid, in a manner analogous to the synthesis of IBX, affords m-IBX (eq 7). 4... 

In the procedure described below, luminol is synthesized by a sequence of reactions that involves the condensation of 3-nitrophthalic acid (16) with hydrazine (18) to produce 3-nitrophthalhydrazide (20), which is then reduced by sodium dithionite to form luminol (Eq. 20.12). The chemiluminescent reaction will then be demonstrated by mixing luminol with hydrogen peroxide and potassium ferri-cyanide, K2pe(CN) (Scheme 20.3). 

A sample of 4-nitrophthalic anhydride (64 g, 0.33 mol) was added to 500 mL of dry benzene, followed by the slow addition with stirring of 107 g (0.80 mol) of aluminum chloride. The mixture was then heated at reflux until the evolution of hydrogen chloride ceased, then cooled. The aluminum complex was destroyed by the addition of 500 g of ice and 200 mL of 12 M HCl. The benzene was extracted with water and with saturated NaCl and dried over sodium sulfate. The benzene was then removed, and the crude benzoylbenzoic acids were placed in a Soxhlet and extracted with methanol for 24 hrs. The extract was allowed to cool and after filtration gave 2-benzoyl-4-nitrobenzoic acid. Yield 10%, m.p. 158-160 C (lit. 163-5 C). The other isomer, 2-benzoyl-5-nitrobenzoic acid, was isolated by reducing the filtrate to one-third its volume and cooling. The yield was 50.0 g (55.6%) m.p. 207-211 C (lit. S 212 °C). A solution of 50.0 g (0.18 mol) of 2-benzoyl-5-nitrobenzoic acid and 50 mL of thionyl chloride was heated at reflux for 3 hrs. After the excess thionyl chloride was removed under vacuum, 500 mL of dry benzene was added to the pseudoacid chloride. Aluminum chloride (46.0 g, 0.40 mol) was slowly added and the mixture was heated at reflux until the evolution of hydrogen chloride ceased. After the aluminum chloride complex was destroyed... 

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