title: The synthesis and metal ion catalysed hydrolysis of methyl 4,5-diaminopentanoate

authors: Beresford, Geoffrey Derrick

abstract: The diamino acid ester, methyl 4, 5-diaminopentanoate has been prepared for the first time. The successful five step synthesis starting from 4-hydroxybutanoic acid lactone, and two other possible pathways via ethyl 3-formylpropanoate, are described. 
pKₐ values for 4,5-diaminopentanoic acid dihydrochloride and its a methyl ester dihydrochloride (determined by potentiometric titration at 25°C and I= 0.10molℓ⁻¹) are discussed in relation to those for other 1,2-diamines.
Stability constants of Cu(II) complexes of 4,5-diaminopentanoic acid and its methyl ester were evaluated from potentiometric titration data by the program SCOGS on a PDP 11/70 computer. Both compounds form high stability constant 1:1 and 1:2 complexes with Cu(II). (For 4,5-diaminopentanoic acid log K₁ = 10.94, log K₂ = 9.40 and for methyl 4,5-diaminopentanoate log K₁ = 9.84, log K₂ = 8.51, at 25°C and I= 0.10molℓ⁻¹). A variety of protonated complexes were also present at lower pH. 
pH-stat and spectrophotometric investigations showed that in the alkaline hydrolysis of methyl 4,5-diaminopentanoate, the simple Bᴀс2 reaction is slow and masked by a competing, extremely rapid, pair of intramolecular aminolysis (lactamisation) reactions. These involve competition between five and six membered lactam ring closure. Overall constants of the order 10³ℓmol⁻¹s⁻¹ at 25°C and I = 0.10molℓ⁻¹ are observed.
The Cu(II) catalysed hydrolysis of methyl 4,5-diaminopentanoate was studied at constant pH using a pH-stat. The kinetics of hydrolysis of solutions containing a 1:2 mole ratio of Cu(II): ester are consistent with the two consecutive second order (pseudo-first-order at constant pH) reactions (1) and (2) (where E is the ester and A⁻ the anion, of 4 ,5-diaminopentanoic acid).
CuE₂²⁺ + OH⁻ → CuEA⁺ + CH₃OH 	1
CuEA⁺ + OH⁻ → CUA₂ + CH₃OH 		2
The relative values for the two rate constants obtained (k (CuE₂²⁺) = 2.41ℓmol⁻¹s⁻¹ and k (CuEA⁺) = 0.80ℓmol⁻¹s⁻¹ at 25°C and I = 0.10molℓ⁻¹) can be explained by charge and statistical effects. The value of k(CuEA⁺) was confirmed independently from studies on solutions containing a 2.5:1:4 mole ratio of Cu(II): ester: acid. The value of k(CuEen²⁺) = 0.96ℓmol⁻¹s⁻¹ obtained from solutions containing Cu(II): ester: 1,2-diaminoethane = 2.5:1:4 is approximately k(CuE₂²⁺)/2 as expected statistically. 1:1 Solutions of Cu(II) and methyl 4,5-diaminopentanoate disproportionate, so no values for k(CuE²⁺) could be measured.
The absolute values for the Cu(II) catalysed rate constants are discussed in comparison with those for methyl 2,3-diaminopropanoate and other diamino acid esters. The results for methyl 4,5-diaminopentanoate can be explained by the attenuation of inductive and positive charge effects of the metal ion by the additional methylene groups of the methyl 4,5-diaminopentanoate alkyl chain. Direct methoxycarbonyl-metal ion interaction, presumably absent in methyl 4,5-diaminopentanoate must, therefore, be unimportant in the Cu(II) catalysed hydrolysis of methyl 2,3-diarninopropanoate.

text: The synthesis and metal ion catalysed hydrolysis of methyl 4,5-diaminopentanoate The diamino acid ester, methyl 4, 5-diaminopentanoate has been prepared for the first time. The successful five step synthesis starting from 4-hydroxybutanoic acid lactone, and two other possible pathways via ethyl 3-formylpropanoate, are described. 
pKₐ values for 4,5-diaminopentanoic acid dihydrochloride and its a methyl ester dihydrochloride (determined by potentiometric titration at 25°C and I= 0.10molℓ⁻¹) are discussed in relation to those for other 1,2-diamines.
Stability constants of Cu(II) complexes of 4,5-diaminopentanoic acid and its methyl ester were evaluated from potentiometric titration data by the program SCOGS on a PDP 11/70 computer. Both compounds form high stability constant 1:1 and 1:2 complexes with Cu(II). (For 4,5-diaminopentanoic acid log K₁ = 10.94, log K₂ = 9.40 and for methyl 4,5-diaminopentanoate log K₁ = 9.84, log K₂ = 8.51, at 25°C and I= 0.10molℓ⁻¹). A variety of protonated complexes were also present at lower pH. 
pH-stat and spectrophotometric investigations showed that in the alkaline hydrolysis of methyl 4,5-diaminopentanoate, the simple Bᴀс2 reaction is slow and masked by a competing, extremely rapid, pair of intramolecular aminolysis (lactamisation) reactions. These involve competition between five and six membered lactam ring closure. Overall constants of the order 10³ℓmol⁻¹s⁻¹ at 25°C and I = 0.10molℓ⁻¹ are observed.
The Cu(II) catalysed hydrolysis of methyl 4,5-diaminopentanoate was studied at constant pH using a pH-stat. The kinetics of hydrolysis of solutions containing a 1:2 mole ratio of Cu(II): ester are consistent with the two consecutive second order (pseudo-first-order at constant pH) reactions (1) and (2) (where E is the ester and A⁻ the anion, of 4 ,5-diaminopentanoic acid).
CuE₂²⁺ + OH⁻ → CuEA⁺ + CH₃OH 	1
CuEA⁺ + OH⁻ → CUA₂ + CH₃OH 		2
The relative values for the two rate constants obtained (k (CuE₂²⁺) = 2.41ℓmol⁻¹s⁻¹ and k (CuEA⁺) = 0.80ℓmol⁻¹s⁻¹ at 25°C and I = 0.10molℓ⁻¹) can be explained by charge and statistical effects. The value of k(CuEA⁺) was confirmed independently from studies on solutions containing a 2.5:1:4 mole ratio of Cu(II): ester: acid. The value of k(CuEen²⁺) = 0.96ℓmol⁻¹s⁻¹ obtained from solutions containing Cu(II): ester: 1,2-diaminoethane = 2.5:1:4 is approximately k(CuE₂²⁺)/2 as expected statistically. 1:1 Solutions of Cu(II) and methyl 4,5-diaminopentanoate disproportionate, so no values for k(CuE²⁺) could be measured.
The absolute values for the Cu(II) catalysed rate constants are discussed in comparison with those for methyl 2,3-diaminopropanoate and other diamino acid esters. The results for methyl 4,5-diaminopentanoate can be explained by the attenuation of inductive and positive charge effects of the metal ion by the additional methylene groups of the methyl 4,5-diaminopentanoate alkyl chain. Direct methoxycarbonyl-metal ion interaction, presumably absent in methyl 4,5-diaminopentanoate must, therefore, be unimportant in the Cu(II) catalysed hydrolysis of methyl 2,3-diarninopropanoate.

year: 1977

title: Microsatellite markers for the endemic New Zealand long-tailed bat (Chalinolobus tuberculatus)

authors: Dekrout, Andrea

subjects: Chalinolobus gouldii

abstract: The New Zealand long-tailed bat (Chalinolobus tuberculatus) is an endangered species which is now absent from many habitats where they were previously observed. However, population genetics studies have been hampered by the lack of reliable genetic markers. We have developed 13 microsatellite markers, and at least eight of these are suitable for population studies. Nine of these markers also cross-react with the closely related Australian species C. gouldii. These markers may prove of general utility in the genus Chalinolobus.

text: Microsatellite markers for the endemic New Zealand long-tailed bat (Chalinolobus tuberculatus) The New Zealand long-tailed bat (Chalinolobus tuberculatus) is an endangered species which is now absent from many habitats where they were previously observed. However, population genetics studies have been hampered by the lack of reliable genetic markers. We have developed 13 microsatellite markers, and at least eight of these are suitable for population studies. Nine of these markers also cross-react with the closely related Australian species C. gouldii. These markers may prove of general utility in the genus Chalinolobus.

year: 2009

title: Alum dosing of Waitangi Stream: Biomonitoring of aluminium 2021-2023

authors: Tempero, Grant Wayne

abstract: Continuous alum dosing of the Waitangi Stream at Lake Rotoehu commenced in 2011 to reduce concentrations of dissolved reactive phosphorus in this inflow to the lake and improve water quality. The Bay of Plenty Regional Council contracted the University of Waikato to undertake monitoring of biota in the Waitangi Stream for potential impacts due to alum dosing. Macroinvertebrate community analysis and tissue aluminium concentrations in kōura (Paranephrops planifrons) and goldfish (Carassius auratus) have been undertaken annually since 2013 to determine the impacts and bioaccumulation of aluminium.

text: Alum dosing of Waitangi Stream: Biomonitoring of aluminium 2021-2023 Continuous alum dosing of the Waitangi Stream at Lake Rotoehu commenced in 2011 to reduce concentrations of dissolved reactive phosphorus in this inflow to the lake and improve water quality. The Bay of Plenty Regional Council contracted the University of Waikato to undertake monitoring of biota in the Waitangi Stream for potential impacts due to alum dosing. Macroinvertebrate community analysis and tissue aluminium concentrations in kōura (Paranephrops planifrons) and goldfish (Carassius auratus) have been undertaken annually since 2013 to determine the impacts and bioaccumulation of aluminium.

year: 2024