Hydrobenzoic acid

The diamine (99) was prepared from (S)-proline90b) or (S)-glutamic acid I15) maintaining the asymmetric center. Racemic 2-(anilinomethyl)pyrrolidine, prepared from (RS)-5-oxopyrrolidine-2-carboxylic acid, was effectively resolved into a pair of enantiomers by fractional crystallization of its mandelic acid salt U6). Moreover, the preferential crystallization of its 4-hydrobenzoic acid salt was found to produce both enantiomers in high optical purities by alternate seeding116). 

Hill, G. A., Ratcliffe, J. and Smith, P., 3-Ethoxy-4-hydrobenzoic acid in human urine. Nature 182, 1160 (1958). 

Polyesters are an important class of industrial polymers. The polyester of 4-hydrobenzoic acid (PHBA) has been studied by solid state NMR. PHBA at room temperature exists in two different orthorhombic crystal modifications designated modification I and II. The high symmetry and regularity of the ehain structure gives rise to a high degree of crystallinity and reduced solubility in all common solvents. Above 330°C these modifications reversibly transform to a pseudo-hexagonal structure (HI). The solid state C-NMR spectrum at 75.14 MHz of PHBA whiskers [41] in modification I is shown in Fig. 9.16. A comparison is shown in Table 9.2 of the chemical shifts of the C resonances of PHBA in modification I and the tetramer in solution in ppm downfield from TMS. 

Soil. DT50 c. 10 days Degraded by hydrolysis and debromination to less toxic substance such as hydrobenzoic acid... 

Hermann, K. 1989. Occurrence and content of hydroxycinnamic and hydrobenzoic acid compounds in foods. Crit. Rev. Food Sci. Nutr. 28 315-347. 

Brostow, W. Arkinay, A. Ertepinar, H. Lopez, B. Phase structure and phase diagrams on polymer liquid crystal systems copolymers of PET and p-hydrobenzoic acid. POLYCHAR-3 Proceedings 1993, 3, 46. 

Hexahydroanthranilic Acid o-Aminohexa-hydrobenzoic acid, aminocychhexane-o-carboxylic acid)... 

Several bioactive compounds have been reported for pineapple fruit and juice, including the phenolic compounds p-coumaric, caflfeic, fer-rulic, and p-hydrobenzoic acids as well as vitamin C and carotenoids (Simon et al. 1992 Gardner et al. 2000). More recently, nine major phenolic compoimds were characterized and quantified in 54 commercial samples of pineapple juice concentrate samples— tyrosine, serotonin, di-metiiylhydroxylfuianone, dimethylhydroxylfiiranone b-glucoside, tryptophan, -sinapyl-L-cysteine, iV-g-L-glutamyl-5 -sinapyl-L-cysteine, S-sinapyl glutathione, and p-coumaric acid (Wen and Wrolstad 2002). 

Octahydrodibenzothiophene (73) has been prepared by the following sequence. Friedel-Crafts acylation of 4,5,6,7-tetra-hydrobenzo[6]thiophene with succinic anhydride (87%) or with the ester chloride of succinic acid followed by hydrolysis (80%), yields the keto acid (74). Huang-Minlon reduction of 74 followed by cyclization of the derived acid chloride with stannic chloride yields l-keto-1,2,3,4,6,7,-8,9-octahydrodibenzothiophene (53) (Section V,A). Reduction of 53 gives 73 as a solid (overall yield 32%). 

The synthesis of 4,5,6,7-tetrahydrobenzo[6]thiophen-4-one and -7-one has been described in Section IV, G 4-methyl-4,5,6,7-tetra-hydrobenzo[6]thiophen-5-one is obtained on oxidation of 136 (R = Me) with per benzoic acid.438... 

Friedel-Crafts acetylation of l-methyl-4,5,6,7-tetrahydrobenzo[c]-thiophene is reported10 to give l-acetyl-3-methyl-4,5,6,7-tetrahydro-benzo[c]thiophene. Successive treatment of methyl 4,5,6,7-tetra-hydrobenzo[c]thiophene- 1-carboxylate with /V-bromosuccinimide and sodium methoxide gives benzo[c]thiophene-l-carboxylic acid.16,38... 

When 1,2,3,6-tetrahydrophthalic anhydride (4-cyclohexene-l,2-dicarboxylic acid anhydride) (36) is heated with a mixture of hydrogen sulfide and hydrogen in the presence of cobalt sulfide, it gives octahydrobenzo[c]thiophene (53%) and a trace of 4,5,6,7-tetra-hydrobenzo[c]thiophene.48 Similar treatment of hexahydrophthalic anhydride gives a mixture (69%) of cis- and (rcww-octahydrobenzo[c]-thiophene, which may be separated by VPC.48... 

This ketone may be obtained (80%) by direct oxidation of 4,5,6,7-tetra-hydrobenzo[i>]thiophene with a Ce(IV) salt294 or by cyclization of the rather inaccessible y-(3-thienyI)butyric acid.300 y-(2,5-Di-t-butyl-3-thienyl)-butyric acid is cyclized by PPA with the expulsion of the 2-r-Bu group, to give 72 (R = r-Bu).3012-Acetylthiophene reacts with but-2-ene in the presence of a Mn(III) salt, to give the 4,5-dimethyl derivative of 72 (R = H).302... 

According to Walker s experiments this is not generally the case. From the potassium salt of mandelic acid the expected product, i.e., a mixture of hydrobenzo in and isohydrobenzo in, is formed only in small quantities benzaldehyde, however, is formed in larger quantities. 

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