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To review the radiological terminology used to describe dilated mucin-containing appendiceal lesions with correlation to the histopathological diagnosis.Radiology and histopathology reports for all patients with an abnormally dilated appendix referred to a tertiary peritoneal malignancy centre, between January 2021 and December 2021, were reviewed.Overall, 213 patients were included with a median appendiceal diameter of 25.5 mm (range 10-125 mm). Peritoneal disease was present in 109 patients, with the remaining 104 cases demonstrating a dilated appendix only. Local radiology reports were available for 201 cases with the appendix described in 168 cases as appendiceal mucocoele (n=104), appendiceal neoplasm (n=40), appendicitis (n=18), and dilated appendix (n=6). The appendix was not mentioned in 33/201 (15%), either misinterpreted as other pathology (n=15) or not reported (n=18). Peritoneal malignancy histopathology reports were available in 188 cases and reported as low-grade appendix mucinous neoplasm (LAMN, n=144), high-grade appendix mucinous neoplasm (HAMN, n=13), LAMN with foci of HAMN (n=2), LAMN with neuroendocrine tumour (n=2), LAMN with goblet cell adenocarcinoma (n=1), goblet cell adenocarcinoma (n=8), mucinous adenocarcinoma (n=14), non-mucinous adenocarcinoma (n=1), and benign histology (n=3). Only one case of a true inflammatory "mucocoele"/retention cyst was reported.In this cohort of patients, the overwhelming majority of dilated, mucin-filled appendices contained malignant cells and benign mucin-filled appendices were rare. The present authors advocate that the term "likely appendix mucinous neoplasm" should replace "appendix mucocoele" to represent the most likely pathology and facilitate less ambiguous interpretation in management decisions.

AIM Intra-abdominal fibromatosis is an unusual mesenchymal tumour that can be locally aggressive without any metastatic potential. Fibromatosis may simulate cancer recurrence on imaging surveillance for colorectal cancer follow-up. The optimal treatment of recurrent peritoneal malignancy is cytoreductive surgery (CRS) and hyperthermic intraperitoneal chemotherapy (HIPEC). Confirmatory biopsy of lesions suspicious for colorectal cancer recurrence may not be feasible, thereby rendering surgery the safest option. Our aim was to determine the incidence of fibromatosis in a cohort of patients undergoing CRS and HIPEC for suspected colorectal cancer recurrence. METHODS One hundred and seventy-one CRS and HIPEC cases were performed at our Peritoneal Malignancy Institute between February 2007 and October 2018 for colorectal peritoneal metastases and were included in a prospectively maintained database. RESULTS A total of 49 (29%) of 171 cases were performed for primary colorectal cancer with peritoneal metastases, whereas 122 (71%) of 171 cases were performed for suspected colorectal cancer recurrence detected on surveillance imaging after primary colorectal cancer resection. On histological analysis of the resected specimen, five (4.1%) of 122 cases undergoing CRS and HIPEC for colorectal recurrence had fibromatosis. CONCLUSION Fibromatosis can masquerade as colorectal cancer recurrence. In this series it occurred with an incidence of 4.1% among a cohort of patients undergoing CRS and HIPEC for probable recurrence. Surgical resection may be the only option to confirm the diagnosis and rule out malignancy.

Introduction/ Background Among gastrointestinal (GI) tumours, pseudomyxoma peritonei (PMP) from appendiceal origin has unique clinical and morphologic features. Due to the relative paucity of patients and the absence of therapeutic consensus, evaluation and refinement of the morphologic criteria used for assessment of the disease are still difficult. As a result, a uniformly accepted classification is still lacking. In collaboration with NJ Carr, who initiated the conference consensus process, in Basingstoke, and on behalf of the French group RENA-PATH, 11 experienced GI pathologists agreed to participate to a virtual workshop, in order to assess inter-observer variability in PMP diagnosis and staging. Aims The goal of the study was to evaluate, for appendiceal and peritoneal mucinous neoplasms, the degree of concordance in the identification of diagnostic histological criteria by experienced pathologists, and to assess the degree of inter-individual variation in the application of WHO classification (2010) and TNM staging system (7th edition). Methods A single section stained with hematoxylin and eosin from 9 resected cases of mucinous neoplasms was selected by members of RENA-PATH. All digitalized at a maximum resolution (X40) using an HAMMAMATSU scanner system, to ensure that all participants evaluate exactly the same tumour areas; 1 to 16 questions were prepared for each case. On Teleslide web platform, interactive services provided by TRIBVN. All submitted cases were then reviewed by a panel of 11 pathologists with specific expertise and interest in PMP. Data were analyzed using SAS program. Results Whole slide set evaluated by all participants; no abstention or “unknown diagnosis” for any submitted case. Agreement for classification, WHO 2010: • Appendiceal mucinous neoplasms: LAMN 83 %; mucinous adenocarcinoma 92%. • Peritonei mucinous carcinoma: Low grade 91.7%; high grade 91.7%. • Disagreement on the concept of High Grade AMN defined by low power architecture of LAMN + high grade cytology. • Agreement for using pTNM classification (82%) in PMP. • Pushing Invasion (PI) and dissection by acellular mucin (DAM) in appendix wall are not reproducible criteria and need to be better defined. • Criteria need to be redefined to use HAMN according to a majority of participants. • The identification of signet ring cells is not reproducible; the lesion needs to be better defined. • Invasion of organs and pattern of invasion (broatfront invasion / classic by irregular glands or single cells with desmoplasia) are not reproducible criteria. • Improvement in staging assessment is needed Conclusion: Although histopathological features of peritoneal disease are significant prognostic factors requiring pathologists to classify mucinous carcinoma peritonei (pseudomyxoma peritonei), reproducibility in interpretation must be improved. This international collaborative project allows pathologists worldwide to share their expertise and knowledge through a dedicated interactive workshop session. It is expected an improvement in the management of mucinous neoplasms of the appendix and peritoneum., Diagnostic Pathology, Vol 1 No 8 (2016): 13. European Congress on Digital Pathology

Important differences in free muscle flap survival have been reported in the setting of long arterial and venous vein grafts. The authors provide insight into the etiology of flap failure by addressing the following question: Do differences in flap type result in clinically significant different vascular resistances and consequently anastomotic patency? A total of 15 human flaps were studied intraoperatively: 9 gracilis, 3 rectus abdominis, and 3 latissimus dorsi. The muscle was isolated on a single pedicle and hemodynamic stability was ensured. The venous pedicle was then divided. A timed collection of effluent was used to determine flow. Vascular resistance was calculated by dividing the change in pressure by the flow, and standardizing this for temperature and hematocrit. Average vascular resistance and standard deviation for the gracilis, rectus, and latissimus flaps was 10.34 +/- 7.77 mmHg per milliliter per minute, 2.79 +/- 1.50 mmHg per milliliter per minute, and 3.17 +/- 1.05 mmHg per milliliter per minute respectively. An inverse relationship between muscle vascular resistance and flap mass was found (p < 0.001). This indicates that larger muscles have less vascular resistance. The decreased resistance gives rise to higher flow rates and, as a result, potentially improved vein graft patency. The clinical implication is that a larger flap should be used when high flow-through is critical. The role of flap vascular territory makeup continues to be pursued.

The purposes of this study were to determine the frequency and characteristics of calcification and fibrosis in mesenteric carcinoid tumor as seen on CT scans and to evaluate their possible role in diagnosis.The CT findings in 29 cases of proved mesenteric carcinoid tumor were analyzed retrospectively. Tumors were assessed for size, margin, density, radiating strands, calcification, and associated thickening of the small-bowel wall. Matching histologic sections were available for 21 of the cases. They were reviewed independently for histologic pattern, degree of fibrosis, degree of infiltration along neurovascular bundles, necrosis, lymph node architecture, and calcification or ossification within the mass. CT and pathologic findings were then assessed for possible relationships.Calcification was detected by CT in 70% (21 of 30) of mesenteric masses. Three patterns of calcification were noted: small, stippled calcification (n = 11); coarse, dense calcification (n = 7); and diffuse calcification (n = 3). All calcification was localized within areas of poorly cellular mature fibrous tissue. The degree of radiating strands detected by CT tended to increase with the degree of fibrosis seen histopathologically (p = .06).Calcification in mesenteric carcinoid tumors was observed by CT in most cases of this series. The triad of a calcified mesenteric mass, radiating strands, and adjacent bowel-wall thickening should be considered highly suggestive of carcinoid tumor.

We compared the histologic features of healing acute appendicitis (20 cases) with those of Crohn's disease at the appendix (54 cases), including the presence of granulomas, extrasubmucosal lymphoid aggregates, and subserosal fibrosis. Healing appendicitis assumed two basic patterns: the "usual" pattern, sometimes with an intraluminal cord of granulation tissue, and a xanthogranulomatous pattern. Epithelioid cell granulomas were seen exclusively in Crohn's disease (19/54; 35%). Furthermore, large numbers of lymphoid aggregates involving the muscularis propria or dense concentric subserosal fibrosis exceeding half the width of the muscularis propria in cross-section were signifi cantly associated with Crohn's disease. Xanthogranulomatous features were not seen in the Crohn's cases. The presence of granulomas, extrasubmucosal lymphoid aggre gates, and concentric subserosal fibrosis in an appendectomy specimen may suggest the diagnosis of Crohn's disease. Int J Surg Pathol 2(1):23-30, 1994

Aims: To test the hypothesis that deficient α smooth muscle actin (ASMA) expression in intestinal smooth muscle, as assessed by immunohistochemistry, is specifically associated with clinical evidence of intestinal pseudo-obstruction. Methods: Seventeen archival, formalin fixed, paraffin wax embedded samples of small intestine and 12 samples of large intestine were studied. Two of the small bowel samples and one large bowel sample were from patients with symptoms of intestinal pseudo-obstruction. The controls were longitudinal surgical margins from hemicolectomies performed for carcinoma. Immunohistochemistry was performed using primary antibodies to ASMA, smooth muscle myosin heavy chain (SMMHC), and desmin. The relative intensities of immunohistochemical expression in the circular and longitudinal muscle layers of the muscularis propria were assessed in each sample, for all three markers. Results: All samples showed strong SMMHC and desmin expression in the inner circular and outer longitudinal layers of the muscularis propria. Both small intestinal samples from the cases and 11 of 15 controls showed no or minimal ASMA expression in the inner circular layer, with the remaining four controls also showing ASMA labelling in this layer that was weaker than within the longitudinal muscle. In contrast, intense ASMA expression was seen in both muscle layers within the large intestine in the remaining case, and in the controls. Conclusions: There is insufficient evidence from this study to support the hypothesis that ASMA deficiency in intestinal smooth muscle, as determined by immunohistochemistry on archival tissues, is specifically associated with intestinal pseudo-obstruction.

The differential expression of cytokeratin (CK) 7 and 20 by carcinomas may help in determining the primary site of a metastatic tumour. The aim of this study was to extend the published data on CK7 and CK20 expression in epithelial neoplasms of the gastrointestinal tract by considering the degree of differentiation and including some unusual neoplasms.Cases referred to the Armed Forces Institute of Pathology were studied prospectively for immunohistochemical expression of CK7 and CK20. Lesions from 105 patients were analysed. Adenocarcinomas of the upper gastrointestinal tract were positive for both CK7 and CK20 in 78% of cases; only poorly differentiated lesions were CK7-. Well-differentiated and moderately differentiated adenocarcinomas of the large intestine, including appendix, were CK7-/CK20+ in the great majority of cases, as were goblet cell carcinoids, but half of the poorly differentiated adenocarcinomas exhibited aberrant expression, as did most of the mixed goblet cell carcinoid/adenocarcinomas. All five high-grade neuroendocrine carcinomas were negative for both CK7 and CK20.Not only the site but also the grade and histological type of a gastrointestinal carcinoma should be considered when assessing cytokeratin phenotype.

We report a case of urachal glandular neoplasia in a male aged 72 years. The lesion had a papillary and villiform structure, and exhibited serrated features as seen in some colorectal neoplasms. The tumour cells expressed carcinoembryonic antigen, whereas the normal urachal epithelium did not. There was a striking resemblance to low grade mucinous cystic tumours of uncertain malignant potential as described in the appendix and elsewhere. Although such lesions in the urachus have been called adenomas, we argue that their potential to cause pseudomyxoma peritonei deserves a different terminology, and that 'mucinous tumour of uncertain malignant potential' is appropriate.

Microacinar morphology has been reported as a stage-independent prognostic variable for colorectal cancer. We have undertaken a retrospective analysis to test this observation in patients with colonic as well as rectal adenocarcinoma, and to assess interobserver agreement for identifying microacinar morphology.One hundred and eighty patients with colorectal cancer, 144 colonic and 36 rectal, were assigned to either macroacinar (144) or microacinar (36) groups. There was excellent correlation between two observers examining the colorectal cancers independently (kappa statistic, kappa = 0.87). Patients with microacinar tumours had a significantly reduced median survival compared with macroacinar lesions (46 and 87 months, respectively, P = 0.022) and this morphology was significantly associated with higher Dukes' stage (P = 0.007). Microacinar morphology lacked statistical significance when examined in a multivariate analysis with other prognostic variables, both when colonic and rectal tumours were examined either separately or as a combined colorectal group, but small numbers of rectal tumours in this study make it difficult to draw useful conclusions about microacinar morphology in rectal adenocarcinoma.Microacinar morphology was strongly associated with poor prognosis when examined in isolation but was not found to be an independent factor when examined with other prognostic variables.

The detection of aneuploidy in colonic mucosa by flow cytometric DNA analysis has been advocated as an indicator of high risk for ulcerative colitis (UC) patients developing colon carcinoma. To date, studies have primarily utilized fresh tissue and have had two limitations: a significant number of possible false-positive findings (aneuploidy in the absence of detectable dysplasia) that may be due to DNA degradation, and the inherent inability to perform retrospective studies. The latter has compromised the adequate assessment of flow cytometric DNA analysis for its clinical utility in UC patients. Our objective was to attempt to overcome the limitations that have been present in DNA analysis by flow cytometry.After having established, in our laboratory, an optimal method that allowed reliable DNA analysis on paraffin-embedded mucosal biopsy specimens, we conducted three separate studies to address the above problems associated with DNA analysis with fresh colonic samples: 1) comparison of DNA analysis between fresh and paraffin-embedded colonic mucosal samples from UC patients without dysplasia, 2) correlation between morphology and DNA ploidy on paraffin-embedded tissues showing no dysplasia and various degrees of dysplasia, and 3) sequential analysis of fresh, normal colonic mucosal samples to further evaluate possible causes of false aneuploidy.We observed 1) that there is discordance in DNA ploidy between paraffin-embedded and fresh samples showing no dysplasia in that aneuploidy was found in 33/46 (72%) of fresh samples, whereas 3/40 (7.5%) were aneuploid by biopsies from the corresponding anatomic sites. 2) There is excellent correlation between dysplasia and DNA ploidy results with paraffin-embedded tissue, i.e., none of 16 samples negative for dysplasia, none of seven samples indefinite for dysplasia, and seven of eight samples positive for dysplasia were aneuploid. 3) DNA degradation produced a spurious, near-diploid aneuploid peak in a normal colonic mucosal sample when it was left in saline more than 1 hr before analysis.The above-described results demonstrate that performing flow cytometric DNA analysis with formalin-fixed paraffin-embedded biopsy samples is feasible and that this technique may provide more reliable ploidy results than does the use of fresh samples, when rapid refrigeration and/or freezing of the fresh samples cannot be accomplished consistently, and will permit retrospective DNA ploidy studies assessing risk of cancer in UC patients.

Introduction The current WHO classification of tumours of the digestive system divides pseudomyxoma peritonei into two grades, namely low-grade and high-grade. This study was designed to correlate survival with low-grade and high-grade pseudomyxoma peritonei classified according to the WHO criteria. Methods The histological slides of 274 consecutive patients were reviewed and designated as either low-grade or high-grade. The patients had been referred for cytoreductive surgery. The grade of the pseudomyxoma was correlated with survival data using the Kaplan–Meier method with the log-rank (Mantel-Cox) test. Results 238 (87%) patients had low-grade lesions and 36 (13%) had high-grade lesions. The most common primary tumour was a low grade appendiceal mucinous neoplasm (231 cases, 84%). Seven patients who died within 30 days of their operation (a postoperative mortality of 2.6%) were excluded from survival analysis. Another patient was excluded because of incomplete survival data. The remaining 266 patients showed an overall 5-year survival of 63% in patients with low-grade pseudomyxoma peritonei and 23% in patients with high-grade pseudomyxoma peritonei (p Conclusion Histological classification of pseudomyxoma peritonei as low-grade or high-grade correlates with prognosis. This may identify a group who could benefit from further adjuvant therapy which is not generally advocated for appendiceal mucinous tumours. Competing interests None declared.

The aim of this study was to correlate clinical and pathologic features of squamous cell papillomas of the human esophagus and investigate their pathogenesis and malignant potential.Clinical and pathologic data on 25 patients were studied.All patients in whom the race was known were white, and the majority of lesions occurred in the distal esophagus. There were multiple lesions in five cases. Many cases showed endoscopic evidence of hiatus hernia, gastroesophageal reflux, or esophagitis. No examples of Barrett esophagus were found. No esophageal malignancies occurred, and no dysplasia was seen histologically. Evidence of recurrence was found in only two patients, but several synchronous or metachronous carcinomas of the oro-respiratory tract occurred.Although our findings do not exclude a viral etiology, they suggest a role for mucosal injury and regeneration in the pathogenesis of these lesions. The association with other malignancies may be significant.

This study aimed to determine the diagnostic utility of mast cell densities in distinguishing neurotised ("neural") melanocytic naevi from neurofibromas. Three groups of lesions were studied: neurofibromas, neural naevi, and naevi showing no neural change (control naevi). A Giemsa stain was used to demonstrate mast cells. The median mast cell density in the neurotised naevus group was significantly higher (p < 0.005) than that of both the neurofibroma and control naevus groups, but the distributions of the individual density counts overlapped considerably. The sensitivity and specificity of the mast cell density as a potential discriminator between neurotised naevi and neurofibromas, determined in relation to the optimal discrimination value obtained using Bayes' minimum cost decision rule, were low. It is concluded that mast cell density on its own is of little use as a classification tool but could be of value in the context of a multivariate decision rule.

In an attempt to confirm the presence or absence of central nervous tissue in commercially prepared beefburgers, four burgers were processed and stained using routine histological laboratory techniques. Constituent parts of the burgers could be identified readily. In this small sample no central nervous tissue was found. There is currently considerable general interest in the contents of foodstuffs, particularly now that certain specified bovine offals as well as central nervous tissue have been banned from human consumption. Conventional histological techniques may be of value in analysing the ingredients of beef products.

A case of nodular regenerative hyperplasia (NRH) of the liver is described in association with exposure to the radiographic contrast medium Thorotrast. This is the first case in which the pathological findings have been fully documented. It is suggested that NRH may have developed through Thorotrast induced damage to portal vein radicles.

Chronic idiopathic intestinal pseudo-obstruction (CIIP) is a severe motility disorder associated with significant morbidity. Several histopathological (neuropathic and myopathic) phenotypes have been described but only a single adult with jejunal smooth (circular) muscle alpha-actin deficiency. We present a prospective multinational case series investigating smooth muscle alpha-actin deficiency as a biomarker of this disease.A total of 115 fully clinically and physiologically (including prolonged (24 hour) ambulatory jejunal manometry) characterised CIIP patients from three European centres were studied. Immunohistochemical localisation of actins and other cytoskeletal proteins were performed on laparoscopic full thickness jejunal biopsies and compared with adult controls. Distribution of alpha-actin was also characterised in other gut regions and in the developing human alimentary tract.Twenty eight of 115 (24%) CIIP patient biopsies had absent (n = 22) or partial (n = 6) jejunal smooth muscle alpha-actin immunostaining in the circular muscle layer. In contrast, smooth muscle alpha-actin staining was preserved in the longitudinal muscle and in adult jejunal controls (n = 20). Comparative study of other adult alimentary tract regions and fetal small intestine, suggested significant spatial and temporal variations in smooth muscle alpha-actin expression.The ability to modulate alpha-smooth muscle actin expression, evident in development, is maintained in adult life and may be influenced by disease, rendering it a valuable biomarker even in the absence of other structural abnormalities.

Summary A 22 year old man with Marfan's syndrome died suddenly following acute aortic valve prolapse. Although aortic root involvement in Marfan's syndrome is common, we have found no previous description of this particular complication in the literature.

The concept of the selection of instructional resources is central to a systems, or systematic, approach to education. Faced with requests to run courses on behaviour modification for teachers and allied professionals in the health care services, both on campus and at a distance, the authors designed two courses which had as their core a common audiovisual package, but which differed in respect of the type of personal presentation by teaching staff. The on‐campus course maximised face‐to‐face teaching, while a combination of telephone seminars and minimal face‐to‐face teaching was used in the distance teaching situation. Performance data and students’ responses to a course evaluation questionnaire allowed a comparative evaluation of different components of the two courses. The achievement level of both groups was high, but the telephone seminars were heavily criticised. The role of the telephone seminars is discussed, as are general problems of the transition from a ‘conventional’ course to one making sub...

A kinetic and mechanistic study of the thermal decomposition of copper(II) malonate has been completed in which the rate measurements have been complemented with microscopic and analytical observations for salt that was partly decomposed to various known extents. Plots of the fractional reaction ($\alpha$) against time for the isothermal reactions were approximately sigmoid but were distorted by a significant diminution in rate at the half-way stage ($\alpha \approx$ 0.5). Microscopic observations gave evidence that local fusion occurred soon after the onset of reaction, so that the initial acceleratory behaviour cannot be ascribed to a solid-state nucleation and growth process. From analytical measurements it is concluded that decomposition proceeds to completion by two distinct reactions, involving a stepwise cation reduction: Cu$^{2+}\rightarrow$ Cu$^+\rightarrow$ Cu$^0$. The relatively slower rate of the second reaction accounts for the marked diminution in slope of the $\alpha$-time plots after $\alpha$ = 0.5. The first reaction, copper(II) malonate decomposition, is characterized by a prolonged acceleratory process that obeys the exponential equation ($\ln \alpha$ = kt). This is explained by autocatalytic behaviour in which anion breakdown is promoted by acetate, a reaction product, thus (d$\alpha$/d$t$) = $k\alpha$. Separate experiments confirmed that added copper(II) acetate accelerated the reaction. The decomposition of copper(II) malonate was accompanied by partial fusion, and gas evolution within the viscous melt resulted in the development of an intracrystalline froth-like texture. Such partial melting was, however, localized within the reactant and the sizes and shapes of crystallites did not change markedly during reaction, so that product particles were pseudomorphic with those of the reactant. The final, short deceleratory phase of the first reaction overlapped with the onset of the second reaction. The second reaction was deceleratory throughout and obeyed first-order kinetics. Product acetate was not formed and the decomposition was evidently not influenced by the concurrent breakdown (0.5 < $\alpha$ < 0.75) of acetate remaining after the first reaction. The froth-like structure of the coherent matrix of the residue was retained unchanged between 0.5 < $\alpha$ < 1.0. The immobile component of this residual material was identified as a carbonaceous phase, the product copper atoms possessed sufficient mobility to aggregate in the form of metallic crystallites. Reaction mechanisms to account for the observations are proposed and are discussed with reference to the complementary kinetic, microscopic, and analytical data.

The temperature at which copper(II) malonate decomposes is significantly reduced in crushed mixtures containing excess CuBr 2 . From kinetic and stoichiometric comparisons it was shown that in this process each mole of copper(II) malonate reacted required 3.5 ∓ 0.5 moles CuBr 2 . Decomposition of any excess carboxylate, remaining in such mixtures, was not influenced by the relatively rapid initial reaction. The present reaction can be partially represented as follows CH 2 (COO) 2 Cu + 4CuBr 2 → 5CuBr +1.5CO 2 + Br 2 + HBr together with a (probably polymeric) carbonaceous constituent of the residue. Isothermal CO 2 evolution exhibited a sigmoid shaped CO 2 yield-time curve. This is ascribed to increasing ease of reaction in a reactant phase of increasing mobility, perhaps with local or temporary melting or the generation of a relatively reactive intermediate. The rate subsequently diminishes as the amount of reactant remaining diminishes. A reaction mechanism is proposed in which an essential step is CH 2 (COO) 2 Cu + CuBr 2 → CH 2 (COOCuBr) 2 followed by decomposition of the relatively more reactive bromo salt. This constituent bromide is identified as facilitating the electron transfer steps culminating in carboxylate group breakdown, a role similar to, but more effective than, that of acetate in the autocatalytic decomposition of pure copper(II) malonate.

A case is reported in which a testicular cancer presented as a metastatic deposit in the eyelid. The histological appearances of both the metastasis and the subsequently detected primary were diagnostic of malignant teratoma trophoblastic (MTT). After comments on the testicular tumour, metastases occurring in the eye and adnexa are discussed.

Kinetic studies of the thermal decomposition reactions of copper(II) maleate and of copper(II) fumarate have been undertaken. The mechanistic interpretations of these observations are supported by complementary analytical measurements and microscopic observations for the reactants, the products and salt partially decomposed to appropriate known extents of reaction. Analytical evidence showed that both reactants decompose with stepwise reduction of the cation and reaction was completed through two distinct, consecutive rate processes. During these first reactions copper(II) was reduced to copper(I) by approximately the half-way stage. The second reactions, in which copper(I) reduction to the metal was completed, was, for both salts, the significantly slower process. The first reaction of copper(II) maleate was accompanied by anion isomerization to form predominantly copper(I) fumarate before the onset of the second reaction. Copper(II) fumarate, containing the more stable anion, underwent no such transformation. Electron microscopic observations gave strong evidence that the first reaction in the decomposition of copper(II) maleate was accompanied by at least partial melt formation. Enhanced reactivity within the fused salt explains the sigmoid-shaped product yields vs. time curve. The first reaction of copper(II) fumarate was predominantly deceleratory. The second reactions of both salts obeyed the first-order equation and reactivities are compared quantitatively with the decompositions of the copper(I) salts synthesized within the reaction vessel by heating the acid with excess copper(I) oxide. Mechanisms of the decompositions of both salts [and of copper(II) malonate] are discussed with reference to the kinetic observations and interpretations are complemented by a consideration of the microscopic and the analytical evidence.

Kinetic studies of the thermal decomposition reactions of copper(II) maleate and of copper(II) fumarate have been undertaken. The mechanistic interpretations of these observations are supported by complementary analytical measurements and microscopic observations for the reactants, the products and salt partially decomposed to appropriate known extents of reaction. Analytical evidence showed that both reactants decompose with stepwise reduction of the cation and reaction was completed through two distinct, consecutive rate processes. During these first reactions copper(II) was reduced to copper(I) by approximately the half-way stage. The second reactions, in which copper(I) reduction to the metal was completed, was, for both salts, the significantly slower process. The first reaction of copper(II) maleate was accompanied by anion isomerization to form predominantly copper(I) fumarate before the onset of the second reaction. Copper(II) fumarate, containing the more stable anion, underwent no such transformation. Electron microscopic observations gave strong evidence that the first reaction in the decomposition of copper(II) maleate was accompanied by at least partial melt formation. Enhanced reactivity within the fused salt explains the sigmoid-shaped product yields vs. time curve. The first reaction of copper(II) fumarate was predominantly deceleratory. The second reactions of both salts obeyed the first-order equation and reactivities are compared quantitatively with the decompositions of the copper(I) salts synthesized within the reaction vessel by heating the acid with excess copper(I) oxide. Mechanisms of the decompositions of both salts [and of copper(II) malonate] are discussed with reference to the kinetic observations and interpretations are complemented by a consideration of the microscopic and the analytical evidence.