Collagen
1
erate increase in hydrogen pressure to 30 atms. shortened the hydrogenation time considerably and reduced the cata- lyst requirement by 30 to 50%. The results obtained in laboratory experiments were confirmed on a factory scale. By using pure hydrogen, still further advances in the hydro- genation of commercial oils and fatty acids may be expected. Owing to its high carotene content, palm oil requires more intensive decolourisation than is necessary for other oils and fats. The bleachability of the raw oil is chiefly influenced by its free fatty acid content, preoxidation, and heavy metal contamination. The above factors can be favourably influen- ced by suitable control over the harvesting, recovery, storage, and transport of the raw oil. These investigations have already found practical application in the Congo, where so- called 'SPB Palm Oil' is now produced, which is characterised by first-class bleachability and, as a result, reasonably good stability of the finished product. Treatment of 3-pentachlorphenoxy-l,2-epoxypropane with adipic acid produces 3-pentachlorphenoxy-2-hydroxypropyl mono-adipate, which possesses antibacterial and anti- mycotic activity and hence may be used as an additive for dressings and bacteria- and fungus-resistant coatings. [VB 590137 IE] Reactions with Pyrylium Salts K. Dirnroth. MarburgILahn (Germany) Pyrylium salts are oxonium-carbonium salts which are stabilised by mesomerism as aromatic 6x cations and which add on nucleophilic reagents at C-2, '2-6, or C-4 [I]. The site at which primary addition occurs appears to depend on the type of reaction involved. Detailed examination of the reac- tion of 2,4,6 substituted pyrylium salts with benzylmagne- sium chloride showed that, in this case, primary addition takes place at (2-4. 2,4,6-Triphenylpyrylium perchlorate (I) yields the 4H-pyran derivative 11, which, on treatment with perchloric acid, is con- verted with loss of acetophenone into 1,3 diphenylnaphtha- lene (111) in 90 % yield [2]. Under the influence of bases, such as CaO or preferably disodium oxydiethoxide, I1 undergoes an ally1 rearrangement to give the 2H-pyran derivative (IV), which under the reaction conditions is converted immediately into 1,2,3,5-tetraphenylbenzene (V). It is possible to isolate IV on irradiating I1 with ultraviolet light [3]. Although IV is converted into the benzene derivative V by bases, it does not form a naphthalene derivative 111 under the influence of per- chloric acid. Thus the reverse rearrangement of IV inlo 11 by acids does not occur. C6HS I C6Hs I IV V Isomeric 2H- and 4H-heterocyclics were also isolated in the thiopyran series. In contrast, pyridinium salts yield with benzylmagnesium chloride only N-Alkyl-l,4-dihydropyridine derivatives corresponding to the 4 H-compounds, as shown unequivocally by comparison of their absorption spectra; these cannot be rearranged into 1 ,Zdihydropyridine deri- vatives. A report will be published elsewhere on reactions of pyrylium salts with methylenetriphenyl-phosphorane, which, after addition at C-2 (or C-6), produce benzene derivatives and which yield 1,3,4,6,8-pentaphenyl-5-benzoylazulene in an interesting sequence of changes [4]. [Chemische Gesellschaft Karlsruhe (Germany), May 24th, 19621 [VB 597136 IE] [l] K. Dimroth, Angew. Chem. 72, 331 (1960). [2] K. Dimroth and K. H. Wolf, Angew. Chem. 72,778 (1 [3] H. Kroke, Ph. D. Thesis, Marburg/Lahn 1962. [4] K. H. Wolfand K. Dimruth, unlwblished results. 960). Collagen M. Brenner, Basel (Switzerland) Soluble tropocollagen has been reported to be converted into acid and alkali insoluble collagen via a procollagen step [I]. This process is thougt to involve a nonenzymatic curing pro- cess (aggregation, chemical crosslinking) which goes on throughout life, at later stages assuming the form of ageing. In an investigation of this process F. Verzar (Basel) and the author studied the different forms of collagen and the pro- ducts formed in the course of its thermal contraction [2]. As experimental material, tail tendons from rats of different ages were used. Results: 1. Tropocollagen from 3 months old rats contains significantly more lipophilic amino acids and less of the amino acids characteristic of collagen than either procolla- gen or collagen does M, 2 During thermal shrinkage (64 "C in water), tendons from young (7 months) and old (30 months) animals break down into water-soluble gelatin of high mole- cular weight and an elastic thread; the older the animal&, the slower the rate of degradation. However, the proportiqn of the products of decomposition remains roughly constant (5- 10% insoluble product in the form of the elastic thread). - 3. Surprisingly, the amino acid composition of the insoluble material, whose hydrolysis products contain increasing amounts of amino sugars as the age of the experimental animals increases, is similar to that of tropocollagen, par- ticularly of its a~ component [4]. Conclusion: Collagen is not merely cross-linked tropo- collagen. In the course of its development, either a chemical transformation of the tropocollagen peptide chain or a linking of the tropocollagen onto a second independent collagen intermediate (pro-collagen?) must occur. The results show how essential it is to consider the solid state of col- lagen in chemical investigations of this material. [GDCh-Ortsve-band Frankfurt1Main (Germany), May 24th, 19621. [VB 594139 IE] [l] See, for example, E. Budecke, Angew. Chem. 72, 663 (1960). [2] A. Meyer, Ph. D. Thesis, Universitiit Basel 1962. [3] Compare: D. S. Jackson et al., Biochim. biophysica Acta 27, 418 (1958). [4] K. A. Piez et al., Biochem. Biophys. Acta 53, 596 (1961). Anisotropy of Electronic and Physical Properties of Graphite and its Crystal Compounds A. R. Ubbelohde, London (England) Large single crystals of graphite for investigations of aniso- tropy were obtained from metallic melts, but were never quite pure. A more suitable product was obtained by pyrolysis of CH4 or C3Hs at 1600-2300 OC; this graphite was deposited in the form of plates about 1 mm thick having the carbon layers orientated parallel to the supporting surface of polycrystalline graphite, i.e. the c-axes lie perpendicular to the support, Lat- 462 Angew. Chem. internat. Edit. / Vol. I (1962) I No. 8
Transcript of Collagen
erate increase in hydrogen pressure to 30 atms. shortened the hydrogenation time considerably and reduced the cata- lyst requirement by 30 to 50%. The results obtained in laboratory experiments were confirmed on a factory scale. By using pure hydrogen, still further advances in the hydro- genation of commercial oils and fatty acids may be expected. Owing to its high carotene content, palm oil requires more intensive decolourisat ion than is necessary for other oils and fats. The bleachability of the raw oil is chiefly influenced by its free fatty acid content, preoxidation, and heavy metal contamination. The above factors can be favourably influen- ced by suitable control over the harvesting, recovery, storage,
and transport of the raw oil. These investigations have already found practical application in the Congo, where so- called 'SPB Palm Oil' is now produced, which is characterised by first-class bleachability and, as a result, reasonably good stability of the finished product.
Treatment of 3-pentachlorphenoxy-l,2-epoxypropane with adipic acid produces 3-pentachlorphenoxy-2-hydroxypropyl mono-adipate, which possesses antibacterial and anti- mycotic activity and hence may be used as an additive for dressings and bacteria- and fungus-resistant coatings.
[VB 590137 IE]
Reactions with Pyrylium Salts
K. Dirnroth. MarburgILahn (Germany)
Pyrylium salts are oxonium-carbonium salts which are stabilised by mesomerism as aromatic 6x cations and which add on nucleophilic reagents at C-2, '2-6, or C-4 [I]. The site at which primary addition occurs appears to depend on the type of reaction involved. Detailed examination of the reac- tion of 2,4,6 substituted pyrylium salts with benzylmagne- sium chloride showed that, in this case, primary addition takes place at (2-4. 2,4,6-Triphenylpyrylium perchlorate (I) yields the 4H-pyran derivative 11, which, on treatment with perchloric acid, is con- verted with loss of acetophenone into 1,3 diphenylnaphtha- lene (111) in 90 % yield [2]. Under the influence of bases, such as CaO or preferably disodium oxydiethoxide, I1 undergoes an ally1 rearrangement to give the 2H-pyran derivative (IV), which under the reaction conditions is converted immediately into 1,2,3,5-tetraphenylbenzene (V). It is possible to isolate IV on irradiating I1 with ultraviolet light [3]. Although IV is converted into the benzene derivative V by bases, it does not form a naphthalene derivative 111 under the influence of per- chloric acid. Thus the reverse rearrangement of IV inlo 11 by acids does not occur.
C6HS I
C6Hs I
IV V
Isomeric 2H- and 4H-heterocyclics were also isolated in the thiopyran series. In contrast, pyridinium salts yield with benzylmagnesium chloride only N-Alkyl-l,4-dihydropyridine derivatives corresponding to the 4 H-compounds, as shown unequivocally by comparison of their absorption spectra; these cannot be rearranged into 1 ,Zdihydropyridine deri- vatives. A report will be published elsewhere on reactions of pyrylium salts with methylenetriphenyl-phosphorane, which, after addition at C-2 (or C-6), produce benzene derivatives and which yield 1,3,4,6,8-pentaphenyl-5-benzoylazulene in an interesting sequence of changes [4]. [Chemische Gesellschaft Karlsruhe (Germany), May 24th, 19621 [VB 597136 IE]
[l] K. Dimroth, Angew. Chem. 72, 331 (1960). [2] K. Dimroth and K. H. Wolf, Angew. Chem. 72,778 (1 [3] H. Kroke, Ph. D. Thesis, Marburg/Lahn 1962. [4] K. H. Wolfand K. Dimruth, unlwblished results.
960).
Collagen
M. Brenner, Basel (Switzerland)
Soluble tropocollagen has been reported to be converted into acid and alkali insoluble collagen via a procollagen step [I]. This process is thougt to involve a nonenzymatic curing pro- cess (aggregation, chemical crosslinking) which goes on throughout life, at later stages assuming the form of ageing. In an investigation of this process F. Verzar (Basel) and the author studied the different forms of collagen and the pro- ducts formed in the course of its thermal contraction [2]. As experimental material, tail tendons from rats of different ages were used. Results: 1. Tropocollagen from 3 months old rats contains significantly more lipophilic amino acids and less of the amino acids characteristic of collagen than either procolla- gen or collagen does M, 2 During thermal shrinkage (64 "C in water), tendons from young (7 months) and old (30 months) animals break down into water-soluble gelatin of high mole- cular weight and an elastic thread; the older the animal&, the slower the rate of degradation. However, the proportiqn of the products of decomposition remains roughly constant (5- 10% insoluble product in the form of the elastic thread). - 3. Surprisingly, the amino acid composition of the insoluble material, whose hydrolysis products contain increasing amounts of amino sugars as the age of the experimental animals increases, is similar to that of tropocollagen, par- ticularly of its a~ component [4]. Conclusion: Collagen is not merely cross-linked tropo- collagen. In the course of its development, either a chemical transformation of the tropocollagen peptide chain or a linking of the tropocollagen onto a second independent collagen intermediate (pro-collagen?) must occur. The results show how essential it is to consider the solid state of col- lagen in chemical investigations of this material. [GDCh-Ortsve-band Frankfurt1 Main (Germany), May 24th, 19621. [VB 594139 IE]
[l] See, for example, E. Budecke, Angew. Chem. 72, 663 (1960). [2] A. Meyer, Ph. D. Thesis, Universitiit Basel 1962. [3] Compare: D. S. Jackson et al., Biochim. biophysica Acta 27, 418 (1958). [4] K. A. Piez et al., Biochem. Biophys. Acta 53, 596 (1961).
Anisotropy of Electronic and Physical Properties of Graphite and its Crystal Compounds
A . R. Ubbelohde, London (England)
Large single crystals of graphite for investigations of aniso- tropy were obtained from metallic melts, but were never quite pure. A more suitable product was obtained by pyrolysis of CH4 or C3Hs at 1600-2300 OC; this graphite was deposited in the form of plates about 1 mm thick having the carbon layers orientated parallel to the supporting surface of polycrystalline graphite, i.e. the c-axes lie perpendicular to the support, Lat-
462 Angew. Chem. internat. Edit. / Vol. I (1962) I No. 8
