title: Acid catalysed acetylene-allene isomerisations

authors: Barry, B. J.

abstract: The isomerisations of 1-, 2- and 3-hexyne and of 1,2- and 2,3-hexadiene have been studied in various acid catalysts, all of which were anhydrous solutions in sulpholane. The principal catalysts were HBF₄ and HPF₆ while others used were BF₃, PF₅, PF₅/H₂O, HClO₄, HSO₃F, AsF₅, HAsF₆, AsF₅/SO₃, and H₂SO₄.
  
The evidence for all catalysts favours a stepwise hexyne-hexadiene-hexyne pathway. In the case of the protonic acids it is proposed that vinyl cations were formed by protonation of the isomers and that the subsequent deprotonation occurred from another site in the molecule:

-C≡C-CH₂- + H⁺⇌-CH=C-CH₂-⇌-CH=C=CH- + H⁺

The most probable explanation for the Lewis acid catalysed reaction is that a co-catalyst (such as water) is present so that the true catalyst is a protonic acid; however, alternative mechanisms are discussed. 

The isometric conjugated dienes were found to be unstable in the reaction media. The implications of this for the reaction mechanisms are discussed.

Free energy changes in the isomerisations could not be determined since equilibration studies were not carried out due to irreversible side reactions. However, a kinetic analysis leads to an order of stability consistent with published data.

The side reactions also prevented the calculation of accurate kinetic data and the reaction order. 

The addition products formed in the HBF₄ catalysed reactions were identified as 2,2- and 3,3-difluorohexane. 

Nmr, conductivity and solvent extraction studies provided evidence on the nature of the acid species and suggested that complex formation occurred between the isomers and the acids. It is proposed that the complex formation is responsible for the production of hexanones in the HPF₆ catalysed reactions.

Hexanone production in the H₂SO₄ catalysed reaction was found to occur before water was added to quench the reaction, contrary to the mechanism proposed previously.
A possible alternative mechanism is discussed.

text: Acid catalysed acetylene-allene isomerisations The isomerisations of 1-, 2- and 3-hexyne and of 1,2- and 2,3-hexadiene have been studied in various acid catalysts, all of which were anhydrous solutions in sulpholane. The principal catalysts were HBF₄ and HPF₆ while others used were BF₃, PF₅, PF₅/H₂O, HClO₄, HSO₃F, AsF₅, HAsF₆, AsF₅/SO₃, and H₂SO₄.
  
The evidence for all catalysts favours a stepwise hexyne-hexadiene-hexyne pathway. In the case of the protonic acids it is proposed that vinyl cations were formed by protonation of the isomers and that the subsequent deprotonation occurred from another site in the molecule:

-C≡C-CH₂- + H⁺⇌-CH=C-CH₂-⇌-CH=C=CH- + H⁺

The most probable explanation for the Lewis acid catalysed reaction is that a co-catalyst (such as water) is present so that the true catalyst is a protonic acid; however, alternative mechanisms are discussed. 

The isometric conjugated dienes were found to be unstable in the reaction media. The implications of this for the reaction mechanisms are discussed.

Free energy changes in the isomerisations could not be determined since equilibration studies were not carried out due to irreversible side reactions. However, a kinetic analysis leads to an order of stability consistent with published data.

The side reactions also prevented the calculation of accurate kinetic data and the reaction order. 

The addition products formed in the HBF₄ catalysed reactions were identified as 2,2- and 3,3-difluorohexane. 

Nmr, conductivity and solvent extraction studies provided evidence on the nature of the acid species and suggested that complex formation occurred between the isomers and the acids. It is proposed that the complex formation is responsible for the production of hexanones in the HPF₆ catalysed reactions.

Hexanone production in the H₂SO₄ catalysed reaction was found to occur before water was added to quench the reaction, contrary to the mechanism proposed previously.
A possible alternative mechanism is discussed.

year: 1973

title: Pliocene Te Aute limestones, New Zealand: Expanding concepts for cool-water shelf carbonates

authors: Nelson, Campbell S.

subjects: limestone

abstract: Acceptance of a spectrum of warm- through cold-water shallow-marine carbonate facies has become of fundamental importance for correctly interpreting the origin and significance of all ancient platform limestones. Among other attributes, properties that have become a hallmark for characterising many Cenozoic non-tropical occurrences include: (1) the presence of common bryozoan and epifaunal bivalve skeletons; (2) a calcite-dominated mineralogy; (3) relatively thin deposits exhibiting low rates of sediment accumulation; (4) an overall destructive early diagenetic regime; and (5) that major porosity destruction and lithification occur mainly in response to chemical compaction of calcitic skeletons during moderate to deep burial. The Pliocene Te Aute limestones are non-tropical skeletal carbonates formed at paleolatitudes near 40-42°S under the influence of commonly strong tidal flows along the margins of an actively deforming and differentially uplifting forearc basin seaway, immediately inboard of the convergent Pacific-Australian plate boundary off eastern North Island, New Zealand. This dynamic depositional and tectonic setting strongly influenced both the style and subsequent diagenetic evolution of the limestones. Some of the Te Aute limestones exhibit the above kinds of "normal" non-tropical characteristics, but others do not. For example, many are barnacle and/or bivalve dominated, and several include attributes that at least superficially resemble properties of certain tropical carbonates. In this regard, a number of the limestones are infaunal bivalve rich and dominated by an aragonite over a calcite primary mineralogy, with consequently relatively high diagenetic potential. Individual limestone units are also often rather thick (e.g., up to 50-300 m), with accumulation rates from 0.2 to 0.5 m/ka, and locally as high as 1 m/ka. Moreover, there can be a remarkable array of diagenetic features in the limestones, involving grain alteration and/or cementation to widely varying extents within any, or some combination of, the marine phreatic, burial, and meteoric diagenetic environments, including locally widespread development of meteoric cement sourced from aragonite dissolution. The message is that non-tropical shelf carbonates include a more diverse array of geological settings, of skeletal and mineralogical facies, and of diagenetic features than current sedimentary models mainly advocate. While several attributes positively distinguish tropical from non-tropical limestones, continued detailed documentation of the wide spectrum of shallow-marine carbonate deposits formed outside tropical regions remains an important challenge in carbonate sedimentology.

text: Pliocene Te Aute limestones, New Zealand: Expanding concepts for cool-water shelf carbonates Acceptance of a spectrum of warm- through cold-water shallow-marine carbonate facies has become of fundamental importance for correctly interpreting the origin and significance of all ancient platform limestones. Among other attributes, properties that have become a hallmark for characterising many Cenozoic non-tropical occurrences include: (1) the presence of common bryozoan and epifaunal bivalve skeletons; (2) a calcite-dominated mineralogy; (3) relatively thin deposits exhibiting low rates of sediment accumulation; (4) an overall destructive early diagenetic regime; and (5) that major porosity destruction and lithification occur mainly in response to chemical compaction of calcitic skeletons during moderate to deep burial. The Pliocene Te Aute limestones are non-tropical skeletal carbonates formed at paleolatitudes near 40-42°S under the influence of commonly strong tidal flows along the margins of an actively deforming and differentially uplifting forearc basin seaway, immediately inboard of the convergent Pacific-Australian plate boundary off eastern North Island, New Zealand. This dynamic depositional and tectonic setting strongly influenced both the style and subsequent diagenetic evolution of the limestones. Some of the Te Aute limestones exhibit the above kinds of "normal" non-tropical characteristics, but others do not. For example, many are barnacle and/or bivalve dominated, and several include attributes that at least superficially resemble properties of certain tropical carbonates. In this regard, a number of the limestones are infaunal bivalve rich and dominated by an aragonite over a calcite primary mineralogy, with consequently relatively high diagenetic potential. Individual limestone units are also often rather thick (e.g., up to 50-300 m), with accumulation rates from 0.2 to 0.5 m/ka, and locally as high as 1 m/ka. Moreover, there can be a remarkable array of diagenetic features in the limestones, involving grain alteration and/or cementation to widely varying extents within any, or some combination of, the marine phreatic, burial, and meteoric diagenetic environments, including locally widespread development of meteoric cement sourced from aragonite dissolution. The message is that non-tropical shelf carbonates include a more diverse array of geological settings, of skeletal and mineralogical facies, and of diagenetic features than current sedimentary models mainly advocate. While several attributes positively distinguish tropical from non-tropical limestones, continued detailed documentation of the wide spectrum of shallow-marine carbonate deposits formed outside tropical regions remains an important challenge in carbonate sedimentology.

year: 2003-09-01

title: I Muri i Te Ārai:  Ko Ngā Mōrehu Ka Toe: Healing processes in Tangihanga for Wāhine Māori

authors: Paterson, Keriata Jane

subjects: Tangihanga

abstract: This study involved a qualitative examination of the healing elements of tangihanga as described by eight female Māori respondents whose loss was not spousal but was dearly loved. Few substantive contemporary works on the subject of tangihanga experiences and processes existed (Nikora & Te Awekōtuku, 2013).

To contextualise, western society’s cultural death practices were explored from an interdisciplinary perspective. Literature on death and bereavement, the western contemporary funeral industry, the medicalisation of death, western gender roles in death and bereavement, hygiene and contamination issues, ethnicity and cross cultural studies were discussed. These provided an international background against which this study made explicit the cultural differences of death practice and grief in tangihanga for Māori.
Cultural issues for Māori were then discussed in terms of grief, literature on tangihanga, research about Māori women, women and death, issues for Māori women researching Māori women, and where colonization placed Māori women in society. I then described the traditional procedural processes which were sequentially carried out upon the death of a person. I noted the existence of modern variations in death practice, particularly among urban-based Māori. The diverse situations in which we as modern Māori have found ourselves were discussed with some historical context, however it was noted that despite change and diversity, we continued to share many experiences. The perpetuation of tangihanga has been important to the resilience and survival of Māori culture.

The methodology was described, including interview development and recruitment of respondents. The interview experiences, analysis of information provided, and the development of theory and identifying themes were described. The rationale for exploring the backgrounds of the respondents in terms of whānau upbringing, cultural values, and cultural identification over time were discussed. Specific tangihanga were explored in depth as case studies, with analysis and discussion throughout each korero. Key themes in the respondents’ accounts were identified, of the grief and healing processes, examining culturally defined gender contributors to recovery. Social structures and support, ritual, spiritual beliefs and grief practices were described. Aspects of modern life or even tradition which hindered the healing process were identified, as was the impact of grief on the life respondents lead subsequently.

The findings of the research were next discussed. The narratives supported existing literature that the tangihanga was an effective forum for sharing and expression of grief, honouring and farewelling the deceased, and ensuring that members of whānau pani were supported, protected and nurtured by others. Attending tangihanga from childhood allowed respondents to enjoy a sense of belonging and comfort. Two respondents whose childhoods had featured acculturation, felt confusion about their roles and expectations but overcame these feelings when they later learned more about their culture. By adulthood each of the respondents was in a position to control and influence choices made for the tangihanga, thus enabling them to grieve fully.

In the final discussion my theoretical model was presented, limitations of the research discussed, and future research recommendations made.

text: I Muri i Te Ārai:  Ko Ngā Mōrehu Ka Toe: Healing processes in Tangihanga for Wāhine Māori This study involved a qualitative examination of the healing elements of tangihanga as described by eight female Māori respondents whose loss was not spousal but was dearly loved. Few substantive contemporary works on the subject of tangihanga experiences and processes existed (Nikora & Te Awekōtuku, 2013).

To contextualise, western society’s cultural death practices were explored from an interdisciplinary perspective. Literature on death and bereavement, the western contemporary funeral industry, the medicalisation of death, western gender roles in death and bereavement, hygiene and contamination issues, ethnicity and cross cultural studies were discussed. These provided an international background against which this study made explicit the cultural differences of death practice and grief in tangihanga for Māori.
Cultural issues for Māori were then discussed in terms of grief, literature on tangihanga, research about Māori women, women and death, issues for Māori women researching Māori women, and where colonization placed Māori women in society. I then described the traditional procedural processes which were sequentially carried out upon the death of a person. I noted the existence of modern variations in death practice, particularly among urban-based Māori. The diverse situations in which we as modern Māori have found ourselves were discussed with some historical context, however it was noted that despite change and diversity, we continued to share many experiences. The perpetuation of tangihanga has been important to the resilience and survival of Māori culture.

The methodology was described, including interview development and recruitment of respondents. The interview experiences, analysis of information provided, and the development of theory and identifying themes were described. The rationale for exploring the backgrounds of the respondents in terms of whānau upbringing, cultural values, and cultural identification over time were discussed. Specific tangihanga were explored in depth as case studies, with analysis and discussion throughout each korero. Key themes in the respondents’ accounts were identified, of the grief and healing processes, examining culturally defined gender contributors to recovery. Social structures and support, ritual, spiritual beliefs and grief practices were described. Aspects of modern life or even tradition which hindered the healing process were identified, as was the impact of grief on the life respondents lead subsequently.

The findings of the research were next discussed. The narratives supported existing literature that the tangihanga was an effective forum for sharing and expression of grief, honouring and farewelling the deceased, and ensuring that members of whānau pani were supported, protected and nurtured by others. Attending tangihanga from childhood allowed respondents to enjoy a sense of belonging and comfort. Two respondents whose childhoods had featured acculturation, felt confusion about their roles and expectations but overcame these feelings when they later learned more about their culture. By adulthood each of the respondents was in a position to control and influence choices made for the tangihanga, thus enabling them to grieve fully.

In the final discussion my theoretical model was presented, limitations of the research discussed, and future research recommendations made.

year: 2015