TY  - JOUR
AU  - Nytoft, Hans Peter
AU  - Kildahl-Andersen, Geir
AU  - Lindström, Sofie
AU  - Rise, Frode
AU  - Bechtel, Achim
AU  - Mitrović, Danica D.
AU  - Đoković, Nataša
AU  - Životić, Dragana R.
AU  - Stojanović, Ksenija A.
PY  - 2019
UR  - https://cherry.chem.bg.ac.rs/handle/123456789/2811
AB  - Two previously unidentified dehydroabietane isomers were isolated from Miocene Serbian
lignite and Rhaetian (Late Triassic) coaly mudstones from South Sweden and characterized using
NMR-spectroscopy as cis- and trans-dehydroicetexane. Both have a 9(10→20)-abeo-abietane or
icetexane skeleton consisting of a 6-7-6 tricyclic framework with seven carbons in ring B instead of
the usual six in common diterpanes of the abietane-type. Dehydroicetexanes can be detected using GC-MS-MS in m/z 270 → 146 chromatograms without interference from dehydroabietane or other isomers. Dehydroicetexanes are often abundant in high latitude coals and mudstones ranging fromTriassic to Miocene, and in high latitude oils (Canada and Greenland) sourced from terrigenous organic matter. The trans/(cis+ trans) dehydroicetexane ratio is low in immature sediments, but usually around 0.83 in oils and mature sediments with vitrinite reflectance (%Rr) above 0.5 suggesting an equilibrium from the start of the oil window. Dehydroicetexanes are more stable than dehydroabietane and some oils, rich in dehydroicetexanes, contain no dehydroabietane. Precursors could be plant diterpenoids having the icetexane structure, which have been known for more than 40 years and isolated from a variety of higher plant sources, including some angiosperms. Many of the relatively simple icetexanes were isolated for the first time from Chamaecyparis pisifera and related species where they seem to be particularly abundant, suggesting that dehydroicetaxanes may be used as markers for the genus Chamaecyparis or for Cupressoideae in general.
PB  - Elsevier
T2  - Organic Geochemistry
T1  - Dehydroicetexanes in sediments and crude oils: Possible markers for Cupressoideae
DO  - 10.1016/j.orggeochem.2019.01.001
ER  - 

@article{
author = "Nytoft, Hans Peter and Kildahl-Andersen, Geir and Lindström, Sofie and Rise, Frode and Bechtel, Achim and Mitrović, Danica D. and Đoković, Nataša and Životić, Dragana R. and Stojanović, Ksenija A.",
year = "2019",
abstract = "Two previously unidentified dehydroabietane isomers were isolated from Miocene Serbian
lignite and Rhaetian (Late Triassic) coaly mudstones from South Sweden and characterized using
NMR-spectroscopy as cis- and trans-dehydroicetexane. Both have a 9(10→20)-abeo-abietane or
icetexane skeleton consisting of a 6-7-6 tricyclic framework with seven carbons in ring B instead of
the usual six in common diterpanes of the abietane-type. Dehydroicetexanes can be detected using GC-MS-MS in m/z 270 → 146 chromatograms without interference from dehydroabietane or other isomers. Dehydroicetexanes are often abundant in high latitude coals and mudstones ranging fromTriassic to Miocene, and in high latitude oils (Canada and Greenland) sourced from terrigenous organic matter. The trans/(cis+ trans) dehydroicetexane ratio is low in immature sediments, but usually around 0.83 in oils and mature sediments with vitrinite reflectance (%Rr) above 0.5 suggesting an equilibrium from the start of the oil window. Dehydroicetexanes are more stable than dehydroabietane and some oils, rich in dehydroicetexanes, contain no dehydroabietane. Precursors could be plant diterpenoids having the icetexane structure, which have been known for more than 40 years and isolated from a variety of higher plant sources, including some angiosperms. Many of the relatively simple icetexanes were isolated for the first time from Chamaecyparis pisifera and related species where they seem to be particularly abundant, suggesting that dehydroicetaxanes may be used as markers for the genus Chamaecyparis or for Cupressoideae in general.",
publisher = "Elsevier",
journal = "Organic Geochemistry",
title = "Dehydroicetexanes in sediments and crude oils: Possible markers for Cupressoideae",
doi = "10.1016/j.orggeochem.2019.01.001"
}

Nytoft, H. P., Kildahl-Andersen, G., Lindström, S., Rise, F., Bechtel, A., Mitrović, D. D., Đoković, N., Životić, D. R.,& Stojanović, K. A.. (2019). Dehydroicetexanes in sediments and crude oils: Possible markers for Cupressoideae. in Organic Geochemistry
Elsevier..
https://doi.org/10.1016/j.orggeochem.2019.01.001

Nytoft HP, Kildahl-Andersen G, Lindström S, Rise F, Bechtel A, Mitrović DD, Đoković N, Životić DR, Stojanović KA. Dehydroicetexanes in sediments and crude oils: Possible markers for Cupressoideae. in Organic Geochemistry. 2019;.
doi:10.1016/j.orggeochem.2019.01.001 .

Nytoft, Hans Peter, Kildahl-Andersen, Geir, Lindström, Sofie, Rise, Frode, Bechtel, Achim, Mitrović, Danica D., Đoković, Nataša, Životić, Dragana R., Stojanović, Ksenija A., "Dehydroicetexanes in sediments and crude oils: Possible markers for Cupressoideae" in Organic Geochemistry (2019),
https://doi.org/10.1016/j.orggeochem.2019.01.001 . .

TY  - JOUR
AU  - Nytoft, Hans Peter
AU  - Kildahl-Andersen, Geir
AU  - Lindström, Sofie
AU  - Rise, Frode
AU  - Bechtel, Achim
AU  - Mitrović, Danica D.
AU  - Đoković, Nataša
AU  - Životić, Dragana R.
AU  - Stojanović, Ksenija A.
PY  - 2019
UR  - https://cherry.chem.bg.ac.rs/handle/123456789/2846
AB  - Two previously unidentified dehydroabietane isomers were isolated from Miocene Serbian lignite and Rhaetian (Late Triassic) coaly mudstones from South Sweden and characterized using NMR-spectroscopy as cis- and trans-dehydroicetexane. Both have a 9(10 → 20)-abeo-abietane or icetexane skeleton, consisting of a 6-7-6 tricyclic framework with seven carbons in ring B instead of the usual six in common diterpanes of the abietane-type. Dehydroicetexanes can be detected using GC-MS-MS in m/z 270 → 146 chromatograms without interference from dehydroabietane or other isomers. Dehydroicetexanes are often abundant in high latitude coals and mudstones ranging from Triassic to Miocene, and in high latitude oils (Canada and Greenland) sourced from terrigenous organic matter. The trans/(cis + trans) dehydroicetexane ratio is low in immature sediments, but usually around 0.83 in oils and mature sediments with vitrinite reflectance (%R r ) above 0.5, suggesting an equilibrium from the start of the oil window. Dehydroicetexanes are more stable than dehydroabietane and some oils, rich in dehydroicetexanes, contain no dehydroabietane. Precursors could be plant diterpenoids having the icetexane structure, which have been known for more than 40 years and isolated from a variety of higher plant sources, including some angiosperms. Many of the relatively simple icetexanes were isolated for the first time from Chamaecyparis pisifera and related species where they seem to be particularly abundant, suggesting that dehydroicetexanes may be used as markers for the genus Chamaecyparis or for Cupressoideae in general.
PB  - Elsevier
T2  - Organic Geochemistry
T1  - Dehydroicetexanes in sediments and crude oils: Possible markers for Cupressoideae
VL  - 129
SP  - 14
EP  - 23
DO  - 10.1016/j.orggeochem.2019.01.001
ER  - 

@article{
author = "Nytoft, Hans Peter and Kildahl-Andersen, Geir and Lindström, Sofie and Rise, Frode and Bechtel, Achim and Mitrović, Danica D. and Đoković, Nataša and Životić, Dragana R. and Stojanović, Ksenija A.",
year = "2019",
abstract = "Two previously unidentified dehydroabietane isomers were isolated from Miocene Serbian lignite and Rhaetian (Late Triassic) coaly mudstones from South Sweden and characterized using NMR-spectroscopy as cis- and trans-dehydroicetexane. Both have a 9(10 → 20)-abeo-abietane or icetexane skeleton, consisting of a 6-7-6 tricyclic framework with seven carbons in ring B instead of the usual six in common diterpanes of the abietane-type. Dehydroicetexanes can be detected using GC-MS-MS in m/z 270 → 146 chromatograms without interference from dehydroabietane or other isomers. Dehydroicetexanes are often abundant in high latitude coals and mudstones ranging from Triassic to Miocene, and in high latitude oils (Canada and Greenland) sourced from terrigenous organic matter. The trans/(cis + trans) dehydroicetexane ratio is low in immature sediments, but usually around 0.83 in oils and mature sediments with vitrinite reflectance (%R r ) above 0.5, suggesting an equilibrium from the start of the oil window. Dehydroicetexanes are more stable than dehydroabietane and some oils, rich in dehydroicetexanes, contain no dehydroabietane. Precursors could be plant diterpenoids having the icetexane structure, which have been known for more than 40 years and isolated from a variety of higher plant sources, including some angiosperms. Many of the relatively simple icetexanes were isolated for the first time from Chamaecyparis pisifera and related species where they seem to be particularly abundant, suggesting that dehydroicetexanes may be used as markers for the genus Chamaecyparis or for Cupressoideae in general.",
publisher = "Elsevier",
journal = "Organic Geochemistry",
title = "Dehydroicetexanes in sediments and crude oils: Possible markers for Cupressoideae",
volume = "129",
pages = "14-23",
doi = "10.1016/j.orggeochem.2019.01.001"
}

Nytoft, H. P., Kildahl-Andersen, G., Lindström, S., Rise, F., Bechtel, A., Mitrović, D. D., Đoković, N., Životić, D. R.,& Stojanović, K. A.. (2019). Dehydroicetexanes in sediments and crude oils: Possible markers for Cupressoideae. in Organic Geochemistry
Elsevier., 129, 14-23.
https://doi.org/10.1016/j.orggeochem.2019.01.001

Nytoft HP, Kildahl-Andersen G, Lindström S, Rise F, Bechtel A, Mitrović DD, Đoković N, Životić DR, Stojanović KA. Dehydroicetexanes in sediments and crude oils: Possible markers for Cupressoideae. in Organic Geochemistry. 2019;129:14-23.
doi:10.1016/j.orggeochem.2019.01.001 .

Nytoft, Hans Peter, Kildahl-Andersen, Geir, Lindström, Sofie, Rise, Frode, Bechtel, Achim, Mitrović, Danica D., Đoković, Nataša, Životić, Dragana R., Stojanović, Ksenija A., "Dehydroicetexanes in sediments and crude oils: Possible markers for Cupressoideae" in Organic Geochemistry, 129 (2019):14-23,
https://doi.org/10.1016/j.orggeochem.2019.01.001 . .

TY  - JOUR
AU  - Nytoft, Hans Peter
AU  - Vuković, Nikola S.
AU  - Kildahl-Andersen, Geir
AU  - Rise, Frode
AU  - Životić, Dragana R.
AU  - Stojanović, Ksenija A.
PY  - 2016
UR  - https://cherry.chem.bg.ac.rs/handle/123456789/2283
AB  - series of novel C-33-C-35 hexacyclic benzohopanes (C(33)b-C(35)b) were identified in 39 samples of coal extracts and 39 crude oils of different ages from all over the world. C(33)b and C(34)b homologues were isolated, and their structures were determined by nuclear magnetic resonance. The structure of C(35)b benzohopane was proposed based on the mass spectrum and its similarity with the mass spectra of structurally defined C(33)b and C(34)b homologues. The structures of the C(33)b-C(35)b hexacyclic benzohopanes are closely related to isohopanes; both groups are typical for terrestrial organic matter and can be useful in the correlation analysis. A possible pathway of formation of these novel benzohopanes and their hopanoid precursors with an additional branch in the aliphatic side chain is proposed. C(33)b-C(35)b hexacyclic benzohopanes are stable up to the maturity level corresponding to random vitrinite reflectance (Rr) of similar to 0.80%, which was demonstrated by analyzing the samples of different maturity and by the maturation simulation experiments: hydrous pyrolysis of two bituminous coals (Rr = 0.55 and 0.59%) and pyrolysis of an extracted bituminous coal (Rr = 0.56%) and its asphaltenes. This represents a confirmation that the formation of these novel benzohopanes is related to specific depositional conditions and microbial activity during diagenesis. Mature samples (Rr = 0.8%) and hydrous pyrolysate of the bituminous coals (Rr  lt  0.60%) obtained at 330 degrees C show a distinct distribution of benzohopanes in comparison to immature and moderately mature samples, which is characterized by a low abundance of the b series benzohopanes and the presence of regular and numerous other benzohopane isomers. The latter most likely represent isomers of regular and novel benzohopanes with different substitution patterns on the aromatic ring. This isomerization of alkyl groups attached to the aromatic ring, leading to the formation of thermodynamically more stable isomers, is a well-known maturation scenario so far reported in the series of alkylated naphthalenes, phenanthrenes, and dibenzothiophenes. Therefore, in the same way, a distribution of benzohopanes can indicate thermal maturity. In addition to the novel benzohopanes, three series (2 alpha, 2 beta, and 3 beta) of their methylated derivatives were identified in numerous samples. Finally, a novel C-35 heptacyclic benzohopane with an additional cyclopentane ring was also observed in the studied samples, and its structure was tentatively identified based on the mass spectrum. Opposite to the hexacyclic C(33)b-C(35)b benzohopanes, the formation of the C-35 heptacyclic benzohopane does not require a specific hopanoid precursor with two branches in the side chain. Therefore, this compound seems to have less geochemical significance than the new hexacyclic benzohopanes.
PB  - Amer Chemical Soc, Washington
T2  - Energy and Fuels
T1  - Identification of a Novel Series of Benzohopanes and Their Geochemical Significance
VL  - 30
IS  - 7
SP  - 5563
EP  - 5575
DO  - 10.1021/acs.energyfuels.6b00799
ER  - 

@article{
author = "Nytoft, Hans Peter and Vuković, Nikola S. and Kildahl-Andersen, Geir and Rise, Frode and Životić, Dragana R. and Stojanović, Ksenija A.",
year = "2016",
abstract = "series of novel C-33-C-35 hexacyclic benzohopanes (C(33)b-C(35)b) were identified in 39 samples of coal extracts and 39 crude oils of different ages from all over the world. C(33)b and C(34)b homologues were isolated, and their structures were determined by nuclear magnetic resonance. The structure of C(35)b benzohopane was proposed based on the mass spectrum and its similarity with the mass spectra of structurally defined C(33)b and C(34)b homologues. The structures of the C(33)b-C(35)b hexacyclic benzohopanes are closely related to isohopanes; both groups are typical for terrestrial organic matter and can be useful in the correlation analysis. A possible pathway of formation of these novel benzohopanes and their hopanoid precursors with an additional branch in the aliphatic side chain is proposed. C(33)b-C(35)b hexacyclic benzohopanes are stable up to the maturity level corresponding to random vitrinite reflectance (Rr) of similar to 0.80%, which was demonstrated by analyzing the samples of different maturity and by the maturation simulation experiments: hydrous pyrolysis of two bituminous coals (Rr = 0.55 and 0.59%) and pyrolysis of an extracted bituminous coal (Rr = 0.56%) and its asphaltenes. This represents a confirmation that the formation of these novel benzohopanes is related to specific depositional conditions and microbial activity during diagenesis. Mature samples (Rr = 0.8%) and hydrous pyrolysate of the bituminous coals (Rr  lt  0.60%) obtained at 330 degrees C show a distinct distribution of benzohopanes in comparison to immature and moderately mature samples, which is characterized by a low abundance of the b series benzohopanes and the presence of regular and numerous other benzohopane isomers. The latter most likely represent isomers of regular and novel benzohopanes with different substitution patterns on the aromatic ring. This isomerization of alkyl groups attached to the aromatic ring, leading to the formation of thermodynamically more stable isomers, is a well-known maturation scenario so far reported in the series of alkylated naphthalenes, phenanthrenes, and dibenzothiophenes. Therefore, in the same way, a distribution of benzohopanes can indicate thermal maturity. In addition to the novel benzohopanes, three series (2 alpha, 2 beta, and 3 beta) of their methylated derivatives were identified in numerous samples. Finally, a novel C-35 heptacyclic benzohopane with an additional cyclopentane ring was also observed in the studied samples, and its structure was tentatively identified based on the mass spectrum. Opposite to the hexacyclic C(33)b-C(35)b benzohopanes, the formation of the C-35 heptacyclic benzohopane does not require a specific hopanoid precursor with two branches in the side chain. Therefore, this compound seems to have less geochemical significance than the new hexacyclic benzohopanes.",
publisher = "Amer Chemical Soc, Washington",
journal = "Energy and Fuels",
title = "Identification of a Novel Series of Benzohopanes and Their Geochemical Significance",
volume = "30",
number = "7",
pages = "5563-5575",
doi = "10.1021/acs.energyfuels.6b00799"
}

Nytoft, H. P., Vuković, N. S., Kildahl-Andersen, G., Rise, F., Životić, D. R.,& Stojanović, K. A.. (2016). Identification of a Novel Series of Benzohopanes and Their Geochemical Significance. in Energy and Fuels
Amer Chemical Soc, Washington., 30(7), 5563-5575.
https://doi.org/10.1021/acs.energyfuels.6b00799

Nytoft HP, Vuković NS, Kildahl-Andersen G, Rise F, Životić DR, Stojanović KA. Identification of a Novel Series of Benzohopanes and Their Geochemical Significance. in Energy and Fuels. 2016;30(7):5563-5575.
doi:10.1021/acs.energyfuels.6b00799 .

Nytoft, Hans Peter, Vuković, Nikola S., Kildahl-Andersen, Geir, Rise, Frode, Životić, Dragana R., Stojanović, Ksenija A., "Identification of a Novel Series of Benzohopanes and Their Geochemical Significance" in Energy and Fuels, 30, no. 7 (2016):5563-5575,
https://doi.org/10.1021/acs.energyfuels.6b00799 . .

TY  - JOUR
AU  - Nytoft, Hans Peter
AU  - Kildahl-Andersen, Geir
AU  - Šolević-Knudsen, Tatjana
AU  - Stojanović, Ksenija A.
AU  - Rise, Frode
PY  - 2014
UR  - https://cherry.chem.bg.ac.rs/handle/123456789/1882
AB  - A C-30 pentacyclic triterpane eluting slightly after 18 alpha(H)-oleanane in the m/z 191 mass chromatograms of Late Cretaceous/Tertiary terrigenous oils (peak "J'' in the early literature) has been isolated from a Niger Delta oil and identified using NMR spectroscopy as 3 beta-methyl-24-nor-18 alpha(H)-oleanane. The previous assignment as 18 beta(H)-oleanane is therefore partly erroneous. 3 beta-Methyl-24-nor-18 alpha(H)-oleanane affords a larger m/z 412 - gt  356 response than the oleananes and the relative contribution of 3 beta-methyl-24-nor-18 alpha(H)-oleanane to the 412 - gt  191 "oleanane peak'' can be roughly estimated from comparison of the 412 - gt  356/412 - gt  191 ratio from the oleanane peak with that of the pure compounds. 3 beta-Methyl-24-nor-18 alpha(H)-oleanane can be as abundant as 18a(H)-oleanane in oils having a high concentration of early eluting rearranged oleananes. 3 beta-Methyl-24-nor-19 alpha(H)-taraxastane was also tentatively assigned in the oils on the basis of its mass spectrum as well as its gas chromatography and high performance liquid chromatography retention times. 3 beta-Methyl-24-nor-gammacerane was tentatively assigned in a similar way in an oil containing gammacerane. All 3 beta-methyl-24-nor-triterpanes could be formed via dehydration, rearrangement and hydrogenation of triterpenoids having an OH group at C-3. (C) 2014 Elsevier Ltd. All rights reserved.
PB  - Pergamon-Elsevier Science Ltd, Oxford
T2  - Organic Geochemistry
T1  - Compound "J'' in Late Cretaceous/Tertiary terrigenous oils revisited: Structure elucidation of a rearranged oleanane coeluting on GC with 18 beta(H)-oleanane
VL  - 77
SP  - 89
EP  - 95
DO  - 10.1016/j.orggeochem.2014.09.010
ER  - 

@article{
author = "Nytoft, Hans Peter and Kildahl-Andersen, Geir and Šolević-Knudsen, Tatjana and Stojanović, Ksenija A. and Rise, Frode",
year = "2014",
abstract = "A C-30 pentacyclic triterpane eluting slightly after 18 alpha(H)-oleanane in the m/z 191 mass chromatograms of Late Cretaceous/Tertiary terrigenous oils (peak "J'' in the early literature) has been isolated from a Niger Delta oil and identified using NMR spectroscopy as 3 beta-methyl-24-nor-18 alpha(H)-oleanane. The previous assignment as 18 beta(H)-oleanane is therefore partly erroneous. 3 beta-Methyl-24-nor-18 alpha(H)-oleanane affords a larger m/z 412 - gt  356 response than the oleananes and the relative contribution of 3 beta-methyl-24-nor-18 alpha(H)-oleanane to the 412 - gt  191 "oleanane peak'' can be roughly estimated from comparison of the 412 - gt  356/412 - gt  191 ratio from the oleanane peak with that of the pure compounds. 3 beta-Methyl-24-nor-18 alpha(H)-oleanane can be as abundant as 18a(H)-oleanane in oils having a high concentration of early eluting rearranged oleananes. 3 beta-Methyl-24-nor-19 alpha(H)-taraxastane was also tentatively assigned in the oils on the basis of its mass spectrum as well as its gas chromatography and high performance liquid chromatography retention times. 3 beta-Methyl-24-nor-gammacerane was tentatively assigned in a similar way in an oil containing gammacerane. All 3 beta-methyl-24-nor-triterpanes could be formed via dehydration, rearrangement and hydrogenation of triterpenoids having an OH group at C-3. (C) 2014 Elsevier Ltd. All rights reserved.",
publisher = "Pergamon-Elsevier Science Ltd, Oxford",
journal = "Organic Geochemistry",
title = "Compound "J'' in Late Cretaceous/Tertiary terrigenous oils revisited: Structure elucidation of a rearranged oleanane coeluting on GC with 18 beta(H)-oleanane",
volume = "77",
pages = "89-95",
doi = "10.1016/j.orggeochem.2014.09.010"
}

Nytoft, H. P., Kildahl-Andersen, G., Šolević-Knudsen, T., Stojanović, K. A.,& Rise, F.. (2014). Compound "J'' in Late Cretaceous/Tertiary terrigenous oils revisited: Structure elucidation of a rearranged oleanane coeluting on GC with 18 beta(H)-oleanane. in Organic Geochemistry
Pergamon-Elsevier Science Ltd, Oxford., 77, 89-95.
https://doi.org/10.1016/j.orggeochem.2014.09.010

Nytoft HP, Kildahl-Andersen G, Šolević-Knudsen T, Stojanović KA, Rise F. Compound "J'' in Late Cretaceous/Tertiary terrigenous oils revisited: Structure elucidation of a rearranged oleanane coeluting on GC with 18 beta(H)-oleanane. in Organic Geochemistry. 2014;77:89-95.
doi:10.1016/j.orggeochem.2014.09.010 .

Nytoft, Hans Peter, Kildahl-Andersen, Geir, Šolević-Knudsen, Tatjana, Stojanović, Ksenija A., Rise, Frode, "Compound "J'' in Late Cretaceous/Tertiary terrigenous oils revisited: Structure elucidation of a rearranged oleanane coeluting on GC with 18 beta(H)-oleanane" in Organic Geochemistry, 77 (2014):89-95,
https://doi.org/10.1016/j.orggeochem.2014.09.010 . .