Methanolic Hydrogen Chloride Research Articles

Synthesis and properties of the chlorination products of methyl 4‐amino‐2‐hydroxy‐benzoate. IV

AbstractAs described earlier, two isomers with the structure of a methyl 1,3,3,5,5,6‐hexachloro‐4‐chlorimino‐cyclohexanone‐2‐carboxylate‐1 (XXIIIStructural formulae of compounds numbered up to XXXVII are already given in previous publications. and XIV) were isolated from the reaction mixture, obtained by chlorination of methyl 4‐amino‐2‐hydroxybenzoate in carbon tetrachloride.Now still an other isomer (mp 146–148° C) (XXXIX) was isolated which differs from XXIII and XXIV by a different spatial arrangement of the chlorine atoms attached to carbon atoms 1 and 6.This was proved by conversion of XXXIX into 1,1,2,3,5,5,5‐heptachloro‐3‐carbomethoxy‐pentanone‐4‐carboxylic acid‐1 (XIX).Reaction of XXXIX with methanolic hydrogen chloride yielded the same reaction product as obtained earlier from XXIII and XXIV. This fact makes clear that the ring opening during this reaction does not take place between carbon atoms 2 and 3 as was supposed earlier, but between carbon atoms 1 and 2. The reaction product must therefore be described as a dimethyl 1,1,3,3,4,5,5‐heptachloro‐2‐imino‐1,5‐pentane‐dicarboxylate (XXXIIIA). The consequence of this correction is that also for several other compounds mentioned previously changed structures are proposed.Reaction of XXXIX with an aqueous potassium iodide solution yielded methyl 1,3,5,5,6‐pentachloro‐4‐amino‐cyclohexene‐3‐one‐2‐carboxylate‐1 (XL) which differs from its isomer obtained from XXIII and XXIV by an analogous reaction. Both XXXIX and XL could be converted into methyl‐4‐amino‐3,5‐dichloro‐2‐hydroxy‐benzoate by treatment with stannous chloride.

Synthesis and properties of the chlorination products of methyl 4‐amino‐2‐hydroxy‐benzoate. III

AbstractBoth the isomeric chlorination products of methyl 4‐amino‐2‐hydroxy‐benzoate (XIII, P.A.S. methyl ester) with the structure of methyl 1,3,3,5,5,6‐hexachloro‐4‐chlorimino‐cyclohexanone‐2‐carboxylate‐1 (XXIII and XXIV) reacted with an aqueous potassium iodide solution to yield methyl 1,3,5,5,6‐pentachloro‐4‐amino‐cyclohexene‐3‐one‐2‐carboxylate‐1 (XXX). Further reduction converted XXX into methyl 3,5‐dichloro‐4‐amino‐2‐hydroxy‐benzoate (XV). In 2 N sodium hydroxide, one molecule of hydrogen chloride was eliminated from XXX, yielding the yellow product: methyl 1,3,5,6‐tetrachloro‐4‐amino‐cyclohexadiene‐3,5‐one‐2‐carboxylate‐1 (XXXI). Reduction with stannous chloride converted XXXI into methyl 3,5,6‐trichloro‐4‐amino‐2‐hydroxy‐benzoate (XXXII).When reacted with methanolic hydrogen chloride, both the isomers XXIII and XXIV gave an identical reaction product. In view of the fact that the compound did not liberate iodine from a potassium iodide solution, the structure of a dimethyl α‐(1,2,2,4,4,4‐hexachloro‐3‐imino‐butyl)‐α‐chloro‐malonate (XXXIII) was made plausible for this reaction product. Treatment of XXXIII with 2 N sodium hydroxide resulted in the elimination of a molecule of hydrogen chloride. Reduction with stannous chloride converted XXXIII into a pyridine derivative, which is supposed to be a dichloro substitution product of methyl 2‐hydroxy‐6‐methyl‐nicotinate (XXXV) in which the positions of the two chlorine atoms are still unknown.The reaction of XXIV with ethanolic hydrogen chloride led to the formation of two reaction products. One of them is formulated as the diethyl ester homologue of XXXIII (XXXVI), the other one being the methyl ethyl ester homologue (XXXVII). XXXVI was likewise reduced to a 2‐hydroxy‐nicotinic acid derivative.

PREPARATION OF SOME NEW BRANCHED-CHAIN CARBOHYDRATES FROMD-α-FRUCTOHEPTONIC LACTONE

D-α-Fructoheptonic lactone (I) was oxidized with an equimolar amount of periodic acid to give formaldehyde and a hexuronic lactone (II) which was hydrolyzed to crystalline 4-C-hydroxymethyl-L-xyluronic acid (III), (68% yield). Hydrogenation of III gave an aldonic acid which was isolated as crystalline 2-C-hydroxymethyl-L-xylonic lactone (V). Reduction of V by sodium amalgam gave 2-C-hydroxymethyl-D-xylose (VI), which crystallized after purification as the 2,5-dichlorophenylhydrazone. Hydrogenation of VI gave 1,1-di(C-hydroxymethyl)-D-threitol (VII) which was purified as the crystalline hexaacetate. Treatment of III with methanolic hydrogen chloride gave a glassy material which was reduced by sodium borohydride and hydrolyzed by hydrochloric acid to give 4,4-di(C-hydroxymethyl)-D-threose (IX), which was isolated and characterized as the crystalline 2,5-dichlorophenylhydrazone. Oxidation of III by either bromine or nitric acid gave 2-C-hydroxymethyl-D-xylaric acid (IV), which was characterized as the crystalline ammonium salt.

Cellulose Studies

Native cotton and commercial viscose rayon were degraded by using a saturated solution of hydrogen chloride (about 43%) in methanol at 0° C. It was found that, on the average, 8.1 bonds in native cotton suffered methanolysis during the first 6 hrs. of the reaction, whereas in the ensuing period of 666 hrs. only 1.6 bonds became cleaved. The results indicate that the initial reaction comes to a practical standstill after about the same stage of degradation has been reached as in the mild hydrolytic scission of the same materials (D.P. ∼ 250 for cotton, and D.P. ∼ 60 for viscose rayon). In order to gain information as to the nature of the methoxyl groups in the methanolyzed products, a study of the rate of hydrolysis of the latter was made. Evidently, if the classical concept of cellulose structure is correct—that is, if only normal methyl. glucopyranoside end groups are present—then the rate of acid hydrolysis, as measured by the increase in the reducing power, should be of the order of magnitude shown by the normal methyl glucopyranosides. On the other hand, a very fast rate of hydrolysis, which is characteristic for the open-chain dimethyl acetals of the sugars, would constitute evidence for the presence of such types of residues; hence, it would favor the new concept of cellulose structure. The results showed that more than one-half of the material in the case of viscose rayon and about one-half in that of native cotton were hydrolyzed by 0.05N HCl at 60°C in a period of 48 hrs., which is shorter beyond all comparison than the half-life (3,450 hrs.) of methyl α-gluco pyranoside under identical conditions. These results are considered to supply the chemical proof for the presence of the acid-sensitive, open-chain glucose residues which were suggested in the new formula for cellulose.

Esterification of Galacturonic Acid and Polyuronides with Methanol-Hydrogen Chloride

Esterification of Galacturonic Acid and Polyuronides with Methanol-Hydrogen Chloride

STUDIES ON LIGNIN AND RELATED COMPOUNDS: XXVII. METHYLATION AND STRUCTURE OF METHANOL LIGNIN (SPRUCE)

The composition of spruce methanol lignin prepared by the action of anhydrous methanol-hydrogen chloride on spruce meal was found to vary with the temperature and time of extraction. The reaction mixture contains two products, having methoxyl contents of 21.6 and 24%, respectively. Higher temperatures and longer time of heating favor formation of the latter. Long continued extraction of the crude methanol lignin with ether removed the second product (OCH3, 24%). This showed that this was a true "ether-soluble" fraction, but it was not found possible to isolate the pure methanol lignin (OCH3, 21.6%) by this process. The two substances can be separated either by solvent extraction or, as now shown, by use of 8–10% sodium hydroxide. Methylation of methanol lignin with dimethyl sulphate and alkali gives rise to the formation of new hydroxyl groups, the extent of the changes increasing markedly with rise in temperature of methylation and with increase in concentration of alkali used.A methanol lignin (OCH3, 22.3%) on repeated methylation yields a methylated lignin containing 37.2% methoxyl. Degradation during methylation is restricted by the use of acetone as solvent and only a slight excess of alkali (5–10%) at 20 °C. The results indicate the necessity for caution in the interpretation of data based on methylation experiments involving the use of alkali, and point to the presence of heterocyclic oxygen rings, non-furane in type, as part of the lignin structure. When refluxed for 48 hr. with 65 % aqueous methyl alcohol containing 9% sulphuric acid, ether-insoluble methanol lignin (OCH3, 22.3%) yielded a product with methoxyl content 21.3% which decreased to 20.9% when the product was treated for a further 52 hr.

STUDIES ON LIGNIN AND RELATED COMPOUNDS: XX. METHANOL LIGNIN AND ITS RELATION TO THE SO-CALLED "PRIMARY LIGNIN" OF FRIEDRICH AND DIWALD

Pretreatment of spruce wood meal with cold 5% sodium hydroxide decreases the amount of lignin extractable with methanol and anhydrous hydrogen chloride (Hibbert-Brauns method). Such a prior treatment of the wood meal, either in an atmosphere of nitrogen or of air, apparently causes no structural change in the lignin as judged by the methoxyl content. The method of Friedrich and Diwald, which involves a preliminary treatment with 17% hydrochloric acid followed by addition of a hot alcohol, represents a much more drastic process than the Hibbert-Brauns method, as is indicated by the darker color, lower methoxyl content and behavior towards 8–10% alkali of the isolated lignin.Methanol lignin isolated front a resin-free spruce wood meal, previously subjected to treatment with 5% cold alkali in the presence or absence of air, shows no loss of methoxyl groups on treatment with 8–10% alkali; the same is true of the "primary lignin" prepared by the method of Friedrich and Diwald; in both cases the lignin is insoluble in sodium bicarbonate. These facts show that neither methanol lignin nor "native lignin" contains ester methoxyl groups, as assumed by Friedrich and Diwald. Prolonged treatment of methanol lignin with alkali in the presence of air, especially at higher temperatures, apparenthy brings about certain changes in its structure, including possibly the formation of carboxyl groups. The claim of Friedrich and Diwald that their product represents an "unchanged native lignin" is not in accordance with the facts, and their assumption of the presence of carboxyl groups in native lignin is incorrect.