Hamid Mohammed - Academia.edu (original) (raw)
Papers by Hamid Mohammed
Chemistry and Materials Research, 2014
The induced photodegradation of poly hydroxypropyl cellulose films in air was investigated (for 3... more The induced photodegradation of poly hydroxypropyl cellulose films in air was investigated (for 350 hrs.) in presence and absence of benzophenone and eosine dye (photosensitizer) by accelerated weathering tester. The addition of (0.1wt %) of benzophenone and eosine dye to poly hydroxypropyl cellulose films (25µm in thickness) enhanced the photodegradation of the polymer films. The photodegradation rate was followed by increase in carbonyl absorbance of polymers using infrared (I.R.) and UV-visible. spectra respectively and viscosity. The concluded from this work the eosine dye enhance degradation of polymer more than benzophenone. According to the spectra results, the induced photodegradation mechanisms of polymer films were suggested under the experimental conditions employed using UV-radiation at λ = 313 nm , light intensity 3.49*10-5 einsteins.dm-3 .S-1 at temperature 45 o C.
![Research paper thumbnail of Synthesis new fused and non-fused chromene [I] derivatives derived from 2-amino-4-[4-(dimethylamino)phenyl]-5-oxo-4H,5H-pyrano[3,2-c]chromene-3-carbonitrile](https://attachments.academia-assets.com/97857103/thumbnails/1.jpg)
](Chemistry and Materials Research, 2015
Synthesis new fused and non-fused chromene [I] derivatives derived from 2-amino-4-[4-(dimethylami... more Synthesis new fused and non-fused chromene [I] derivatives derived from 2-amino-4-[4-(dimethylamino)phenyl]-5-oxo-4H,5Hpyrano[3,2-c]chromene-3-carbonitrile
Thesis (M.S. in Horticulture)--University of California, Davis, June 1956. Includes bibliographic... more Thesis (M.S. in Horticulture)--University of California, Davis, June 1956. Includes bibliographical references (leaves 27-31).
Urological Research, 2002
The distribution and regional variation of nerves immunoreactive for the neuropeptides pituitary ... more The distribution and regional variation of nerves immunoreactive for the neuropeptides pituitary adenylate cyclase activating polypeptide (PACAP), calcitonin gene-related peptide (CGRP), substance P (SP) and vasoactive intestinal polypeptide were investigated in the urinary bladder and distal ureter of young adult (3 months) and aged (24 months) male Wistar rats by indirect immunohistochemistry. Semi-quantitative estimations of nerve densities were made of peptidergic fibres innervating the dome, body and base of the urinary bladder and distal ureter. Sensory innervation of the dome was very sparse and the overall density of innervation increased progressively towards the base of the bladder. The density of innervation in the aged rats was closely comparable to that in the young adults, with the exception of slight reductions in CGRP and SP innervation of the muscle layer. Moreover, there was a marked reduction in the density of PACAP innervation of the subepithelial plexus and of the muscle layer of the bladder base. However, radioimmunoassay showed no significant difference (P>0.05) in PACAP contents between young and aged rat urinary bladder. In the distal ureter of aged rats the densities of innervation by fibres immunoreactive for SP and PACAP but not CGRP were reduced. These findings suggest that the level of sensory innervation of the bladder and distal ureter are reduced in old age and that the afferent limb of voiding reflexes may in consequence be perturbed. Keywords Sensory neuropeptides AE Urinary bladder AE Rat AE Ageing
Tetrahedron Letters, 2013
ABSTRACT Domino double Heck/electrocyclization/dehydrogenation reactions of 2,3-dibromo-1H-inden-... more ABSTRACT Domino double Heck/electrocyclization/dehydrogenation reactions of 2,3-dibromo-1H-inden-1-one with styrenes provide a convenient synthesis of 2,3-diarylfluorenones.
Tetrahedron, 2012
Arylated xanthones were prepared by site-selective SuzukieMiyaura reactions of the bis(triflate) ... more Arylated xanthones were prepared by site-selective SuzukieMiyaura reactions of the bis(triflate) of 1,3dihydroxyxanthone. The first attack occurs at the sterically less encumbered position 3. The siteselectivity is in contrast to the bis(triflate) of 1,3-dihydroxyanthraquinone.
Synlett, 2013
Suzuki–Miyaura reactions of aromatic bis-triflates, readily available from the corresponding hydr... more Suzuki–Miyaura reactions of aromatic bis-triflates, readily available from the corresponding hydroxylated arenes, often proceed with excellent regioselectivity and provide a convenient approach to various arylated benzene derivatives, such as biphenyls, terphenyls, and arylated benzophenones, naphthalenes, xanthones, flavones, coumarins, anthraquinones, tetralones, and fluorenones. The regioselectivity is controlled by steric and electronic parameters and strongly depends on the structure of the substrates. 1 Introduction 2 Benzoates, Phthalates, and Naphthoates 3 Benzophenones and Diphenyl Sulfones 4 Xanthones and Thioxanthones 5 Flavones and Coumarins 6 Anthraquinones, Tetralones, and Fluorenones 7 Conclusion
Organic Letters, 2011
Potassium Boc-protected aminomethyltrifluoroborate, a primary aminomethyl equivalent, was synthes... more Potassium Boc-protected aminomethyltrifluoroborate, a primary aminomethyl equivalent, was synthesized successfully through a "one-pot" process. With this trifluoroborate, Suzuki-Miyaura cross-coupling reactions were investigated with a variety of both aryl-and hetaryl chlorides in good to excellent yields. Aminomethyl moieties, especially aminomethylated arenes, might be considered privileged substructures because they appear in many bioactive natural products, 1 and they are also used as important intermediates in synthetic organic chemistry (Figure 1). 2 Aminomethylarenes are often synthesized by either reduction of aryl cyanides 3 or oximes 4 (Scheme 1, path A). However, access to primary aminomethyl aryl-and hetaryl compounds with reducible functional groups would not be compatible with this method. An alternative way to install the aminomethylarene moiety is the Staudinger reaction 5 of organic azides with trivalent phosphorus compounds (Scheme 1, path B). Unfortunately, some aryl-and hetaryl azides exhibit significant thermal-or shock-sensitivity. 6 Moreover, the benzylic or pseudobenzylic halide precursors required to prepare the azides are often not readily available.
Org. Biomol. Chem., 2011
Supporting Information Supplementary Material (ESI) for Organic & Biomolecular Chemistry This jou... more Supporting Information Supplementary Material (ESI) for Organic & Biomolecular Chemistry This journal is (c) The Royal Society of Chemistry 2010 General procedure A for Suzuki-Miyaura Cross-Coupling Reactions: The reaction was carried out in a pressure tube. To a dioxane or toluene/dioxane (4:1) suspension (2.5 mL) of the brominated furan, Pd(PPh 3) 4 (2-3 mol%) and of the arylboronic acid 2 (1.0 to 1.1 equiv. per bromine atom of the substrate) was added an aqueous solution of K 2 CO 3 (2 M, 0.5 mL). The mixture was heated at the indicated temperature (80 °C) under Argon atmosphere for the indicated period of time (3-5 h). The reaction mixture was diluted with water and extracted with CH 2 Cl 2 (3 x 25 mL). The combined organic layers were dried (Na 2 SO 4), filtered and the filtrate was concentrated in vacuo. The residue was purified by flash chromatography (silica gel, EtOAc / heptanes). Synthesis of tetraarylfurans 3a-j 2,3,4,5-Tetraphenylfuran (3a). Following general procedure A, compound 3a was prepared from 1 (96 mg, 0.25 mmol), Pd(PPh 3) 4 (9 mg, 3 mol%), 1,4-dioxane (2.5 mL), 2M K 2 CO 3 (0.5 mL) and phenylboronic acid (132 mg, 1.10 mmol) as a white crystalline solid (86 mg, 92%). 1 H
Chemistry and Materials Research, 2014
The induced photodegradation of poly hydroxypropyl cellulose films in air was investigated (for 3... more The induced photodegradation of poly hydroxypropyl cellulose films in air was investigated (for 350 hrs.) in presence and absence of benzophenone and eosine dye (photosensitizer) by accelerated weathering tester. The addition of (0.1wt %) of benzophenone and eosine dye to poly hydroxypropyl cellulose films (25µm in thickness) enhanced the photodegradation of the polymer films. The photodegradation rate was followed by increase in carbonyl absorbance of polymers using infrared (I.R.) and UV-visible. spectra respectively and viscosity. The concluded from this work the eosine dye enhance degradation of polymer more than benzophenone. According to the spectra results, the induced photodegradation mechanisms of polymer films were suggested under the experimental conditions employed using UV-radiation at λ = 313 nm , light intensity 3.49*10-5 einsteins.dm-3 .S-1 at temperature 45 o C.
Chemistry and Materials Research, 2015
Synthesis new fused and non-fused chromene [I] derivatives derived from 2-amino-4-[4-(dimethylami... more Synthesis new fused and non-fused chromene [I] derivatives derived from 2-amino-4-[4-(dimethylamino)phenyl]-5-oxo-4H,5Hpyrano[3,2-c]chromene-3-carbonitrile
Thesis (M.S. in Horticulture)--University of California, Davis, June 1956. Includes bibliographic... more Thesis (M.S. in Horticulture)--University of California, Davis, June 1956. Includes bibliographical references (leaves 27-31).
Urological Research, 2002
The distribution and regional variation of nerves immunoreactive for the neuropeptides pituitary ... more The distribution and regional variation of nerves immunoreactive for the neuropeptides pituitary adenylate cyclase activating polypeptide (PACAP), calcitonin gene-related peptide (CGRP), substance P (SP) and vasoactive intestinal polypeptide were investigated in the urinary bladder and distal ureter of young adult (3 months) and aged (24 months) male Wistar rats by indirect immunohistochemistry. Semi-quantitative estimations of nerve densities were made of peptidergic fibres innervating the dome, body and base of the urinary bladder and distal ureter. Sensory innervation of the dome was very sparse and the overall density of innervation increased progressively towards the base of the bladder. The density of innervation in the aged rats was closely comparable to that in the young adults, with the exception of slight reductions in CGRP and SP innervation of the muscle layer. Moreover, there was a marked reduction in the density of PACAP innervation of the subepithelial plexus and of the muscle layer of the bladder base. However, radioimmunoassay showed no significant difference (P>0.05) in PACAP contents between young and aged rat urinary bladder. In the distal ureter of aged rats the densities of innervation by fibres immunoreactive for SP and PACAP but not CGRP were reduced. These findings suggest that the level of sensory innervation of the bladder and distal ureter are reduced in old age and that the afferent limb of voiding reflexes may in consequence be perturbed. Keywords Sensory neuropeptides AE Urinary bladder AE Rat AE Ageing
Tetrahedron Letters, 2013
ABSTRACT Domino double Heck/electrocyclization/dehydrogenation reactions of 2,3-dibromo-1H-inden-... more ABSTRACT Domino double Heck/electrocyclization/dehydrogenation reactions of 2,3-dibromo-1H-inden-1-one with styrenes provide a convenient synthesis of 2,3-diarylfluorenones.
Tetrahedron, 2012
Arylated xanthones were prepared by site-selective SuzukieMiyaura reactions of the bis(triflate) ... more Arylated xanthones were prepared by site-selective SuzukieMiyaura reactions of the bis(triflate) of 1,3dihydroxyxanthone. The first attack occurs at the sterically less encumbered position 3. The siteselectivity is in contrast to the bis(triflate) of 1,3-dihydroxyanthraquinone.
Synlett, 2013
Suzuki–Miyaura reactions of aromatic bis-triflates, readily available from the corresponding hydr... more Suzuki–Miyaura reactions of aromatic bis-triflates, readily available from the corresponding hydroxylated arenes, often proceed with excellent regioselectivity and provide a convenient approach to various arylated benzene derivatives, such as biphenyls, terphenyls, and arylated benzophenones, naphthalenes, xanthones, flavones, coumarins, anthraquinones, tetralones, and fluorenones. The regioselectivity is controlled by steric and electronic parameters and strongly depends on the structure of the substrates. 1 Introduction 2 Benzoates, Phthalates, and Naphthoates 3 Benzophenones and Diphenyl Sulfones 4 Xanthones and Thioxanthones 5 Flavones and Coumarins 6 Anthraquinones, Tetralones, and Fluorenones 7 Conclusion
Organic Letters, 2011
Potassium Boc-protected aminomethyltrifluoroborate, a primary aminomethyl equivalent, was synthes... more Potassium Boc-protected aminomethyltrifluoroborate, a primary aminomethyl equivalent, was synthesized successfully through a "one-pot" process. With this trifluoroborate, Suzuki-Miyaura cross-coupling reactions were investigated with a variety of both aryl-and hetaryl chlorides in good to excellent yields. Aminomethyl moieties, especially aminomethylated arenes, might be considered privileged substructures because they appear in many bioactive natural products, 1 and they are also used as important intermediates in synthetic organic chemistry (Figure 1). 2 Aminomethylarenes are often synthesized by either reduction of aryl cyanides 3 or oximes 4 (Scheme 1, path A). However, access to primary aminomethyl aryl-and hetaryl compounds with reducible functional groups would not be compatible with this method. An alternative way to install the aminomethylarene moiety is the Staudinger reaction 5 of organic azides with trivalent phosphorus compounds (Scheme 1, path B). Unfortunately, some aryl-and hetaryl azides exhibit significant thermal-or shock-sensitivity. 6 Moreover, the benzylic or pseudobenzylic halide precursors required to prepare the azides are often not readily available.
Org. Biomol. Chem., 2011
Supporting Information Supplementary Material (ESI) for Organic & Biomolecular Chemistry This jou... more Supporting Information Supplementary Material (ESI) for Organic & Biomolecular Chemistry This journal is (c) The Royal Society of Chemistry 2010 General procedure A for Suzuki-Miyaura Cross-Coupling Reactions: The reaction was carried out in a pressure tube. To a dioxane or toluene/dioxane (4:1) suspension (2.5 mL) of the brominated furan, Pd(PPh 3) 4 (2-3 mol%) and of the arylboronic acid 2 (1.0 to 1.1 equiv. per bromine atom of the substrate) was added an aqueous solution of K 2 CO 3 (2 M, 0.5 mL). The mixture was heated at the indicated temperature (80 °C) under Argon atmosphere for the indicated period of time (3-5 h). The reaction mixture was diluted with water and extracted with CH 2 Cl 2 (3 x 25 mL). The combined organic layers were dried (Na 2 SO 4), filtered and the filtrate was concentrated in vacuo. The residue was purified by flash chromatography (silica gel, EtOAc / heptanes). Synthesis of tetraarylfurans 3a-j 2,3,4,5-Tetraphenylfuran (3a). Following general procedure A, compound 3a was prepared from 1 (96 mg, 0.25 mmol), Pd(PPh 3) 4 (9 mg, 3 mol%), 1,4-dioxane (2.5 mL), 2M K 2 CO 3 (0.5 mL) and phenylboronic acid (132 mg, 1.10 mmol) as a white crystalline solid (86 mg, 92%). 1 H